Note: Descriptions are shown in the official language in which they were submitted.
0~02/~4 lS:33 1er70330532;~0 ~ls~ru~ r Ul'~ Wlr~ lUll
~l~R~; U rl~t~ rlU U J ~r
PCTJUS 92/0~88
.
2 1 1 6 6 6 8 ED-0377-C
TITL~3:
10 ~
,..~
Thi8 applic~tion i~ a con~nuation~ part of appl~cation
Ss~ xr 07/631,26a, filcd I)ecember ~0, 1990 (ED-377-
B), ~h~ch i~ itself a file wrapper continuation o~ applica~on
Se~ial Number 071388,546, ~iled August ~!~ 1989 (ED-3T7) (nolw ~.
aband~ned~. /
Subjcct matter di~closcd herein i~ clo~ed a~d c~aimed
in copending appL;cation Serial Number 07/838,638, filed
August 30, 1991, tL'dcd "An Optical P`ibcr Con~ector Havi~g An
Apparabls For Po8itio~g The Center Of An Op~ical Fiber Along
A P~determincd Refa~nce Axis" q3D-377-D), th~t ~pplica~on
2~ bemg a ¢onffnuation~ part of ~oper~ pplication Serial
Number 07t~i2~,001, filcd December 17,l9gO (II;D-377~A), whic~ is
itself a ~ion of applica~ion 8eri~ Numbe~ 07/388,546, fi~ed
Au~st 2, 1989 (ED-377) (now aba~don~).
au~ect m~ter disclo3ed he~em i~ also di~ ed and
~laimed i~ cope~ding applica'don &~i~l Number 07175~,283,
filod contes~n~oraneou~ly hetewi~ titlcd "Opto-Electronic
Component Ha~ing Positioned Op~ical ~iber A~sociated
Th~:rewi~" (I~:D-378-A), that application bein~ a contis~ation-in-
3~ part of copend~ appic~ n Serial Number 07/38~,548~ filed
August 2, 1 g8~ (ED-~7a).
- SUBST~TUl E SHEET
IPEA~
wo 93/05415 , Pcr/uss2/073ss
;
2116668
BACKGROUND OFT~ I~VI~ION
Ficld Of The Invcntion The present invention relatcs to
5 a posidoning apparatus for positioning the ccntcr~of an`optical
fiber or other small dimensioned cylindrical member, such as
capillary tubing, along a- prcdetcrmincd rcfcrcncc axis
independently of variadons in thc outside diameter of the
membcr.
i
cs~ri~tion Of The P~ior Art Devices arc Icnown for
posidoning an opdcal fibcr so that the axis of thc fiber is
positioncd with rcspect to a rcfcrcncc axis. A typical cxpedicnt
uscd in such deviccs is a gencrally V-shapcd groovc that is
15 fonned in a substrate material and which scrves as a cradlc to
accept thc ~lber being posidoned. Representativc of such
dovices is that shown in United States Patent 4.756,591
(F~scher ct al.), whcrcin a V-groovc is f~med in a silicon
substrato and an clastomcric mcmber is biasod against the
20 fiber to boW it in thc groovc. Thc groovc may be stcpped to
providc a dceper groovc scgmcnt to hold thc jaclcet of thc fiber
within thc dcvicc.
Unitcd States Patcnt 4,756,591 (Shccm) discloscs a
25 groo~ed silicon substratc having a pair of intcrsecting V-
groovcs thercin. A fibcr to be positioned is disposcd in one of
the groovcs while a shim is disposed in the othcr of the
groovcs. Tbe shim may take~ thc f~rm of a tapered or an
Icccentric fibcr, which wben respcctivcly slid or rotatcd undcr
30 thc first fibcr serves to lift the same to bring thc a~cis thercof
into alignmcnt with a refercnce axis. A cover may be
positioncd abovc thc substratc to assist in clamping the first
fiber into positio-.
wo 93/0s4ts Pcr/uss2/0738s
3 2116668
United States Patent 4,~02,727 (Stanley) also discloses a
posidoning arrangement for optical components and
waveguides wbich utilizes a V-grooved structure. United
States Patent 4,826,272 (PimpineUa et al.) and United States
5 Patent 4,830,450 (Connell et al.) discloses arrangem-ents for
positioning an optical fiber that utilize members baving
frustoconical apertures therethrough.
It is belieYed that single crystalline silicon is the material
10 of ehoice of the devices above mendoned because of tbe
proclivity of crystalline silicon to be etched along precise
crgstallographic planes, thus forming precise grooves or
structural features by photolithographic microfab~ication
teehniques. Etehants exist tbat act upon a selected
15 erystdlograpbic plane to a differendal degree than upon an
adjaeent plane, pennitdng tbe needed preeise eontrol. V-
grooves, in partieular, ean be etehed to a eontrolled width and
truneated deptb. Under some eonditions V-grooves may be
etebed in a self-limidng operation. The photolithograpbic
20 microfabricadon proeess is generally deseribed by 8rodie and
Muray, "Tbe Physies of Microfabrieadonn, Plenum Publishing,
New York (1982).
Optieal fibers inelude an inner eore having a
25 predetermincd index of refraedon surrounded by a cladding
layer of a lower index. The inner eore is tbe medium in which
the optieal energy is guided, while tbe eladding layer defines
tbe index bounda~y with tbe core. Tbe outer diameter of tbe
fiber may vary in dimension about a predetermined nominal
30 dimension. It has been seen, for example, tbat two nomina!ly
identieal fibers from tbe same manufacturer may ~rary in
outside diametriea1 dimension by as much as plus or minus
four (4) n~icrometers. Tbis fiber to fiber ~rariadon in outer
diameter makes diffieult tbe accurate positioning of the axis of
35 the eore of a fiber with respect to a predetermined reference
wo 93/05415 Pcr/uss2/0738s
2116~68
axis using a positioning apparatus having a V-grooved
structure.
In view of the foregoing it is believed advantageous to
5 mal~e usc of tbe ability of microfabdcadon tech~i~es to form
accurate structurcs, channcls and/or surfaccs in a crystalline
matcrial to construct a posidoning apparatus that will
accurately position thc ccntcr of the ffber, or of any other
clongatcd generally cylindrical membcr having small
IO dimcnsions (such as capillary tubing), with respect to a
predetcrmined refcrcncc axis. Moreover, it is bclieved
advantageous to provide a positioning apparatus that
consistcntly aligns the predctermined point on the ffber or
other cylindrical mcmber with the refcrcncc axis without
15 requiring great technical sldll, cxpcnsive apparatus, and
cxtcnsivc alignment procedures.
, "
.
wo 93/05415 Pcrluss2/07388
2116663
~UMMARY OF THE lNVENTlON
The prcscnt invention rclatcs to a positioning apparatus
for positioning a pr~dctcrmined point, such as the geometric
5 ccntcr, on thc end facc of a cylindrical member,,such as`an
optical fiber, along a predetermined reference axis. In a
preferred casc the posidoning apparatus includes a first and a
sccond arm, cach of which has at least a first and a sccond
sidcwall that coopcrate to dcfine a groove thercin. The groove
10 in cach arm is prefcrably a convcrging groovc so that when the
arms arc arranged in supcrimposed tclationship the converging
groovcs cooperate to define a funnel-like channel over at Icast
a predctermincd portion of its Icngth. The channel has an inlet
cnd and an outlet end and a rcferencc axis extcnding
15 thercthrough. A fibcr inlroduced into the inlet end of the
channel with its axis spaced from the reference axis is
displaceable by contact with at least onc of thc sidcwalls on
one of tbe a~ns to place a predetermined point on an end face
- of the member into alignment with thc rcferencc axis where it
is therc bcld by contact with tbe first and second arms. To
guide the fiber toward the inlet end of the channel each of the
first and the second arms includes a trough therein, each
trough bcing disposed on an arm a predetermined distance
bchind the groove in that arm, so that in the closed position the
troughs cooperate to define a guideway.
The arms having the converging grooves therein may, as
is prefetred, be movable from a first, closed, position to a
second, centering, position. The superimposed arms are, in this
30 instance, mounted cantilevered fashion, to a foundation. Means
is provided for biasing each of the arms with a substantially
equal and oppositely directed biasing force toward the first
position. ln the preferred implementation the biasing means
comprises a rcduccd thickness portion in each of the first and
the second arms, the teduced thickness ponion defining a
Wo 93/0~41s Pcr/us92/o73ls
2ll666~
- flexure in each arm which, when each arm is deaected by
contact with the cylindrical membcr, gcncrates a force on each
arm to bias each arm toward the closcd position.
It should be understood that so long as the,~ins are-`
movable and biased toward the closcd posidon, it is not
required that tbe grooves formed thcrcin are con~rerging
grooves. Accordingly, other positioning apparatus in which the
arms are movable but in which the grooves in each of the arms
have a form other than a converging groove are to be
construed as Iying within the contemplation of the invention.
Succinctly statcd, the prescnt invcntion cncompasses any
positioning apparatus having arms that are movable whether
the groove in cach arm take the form of a converging groove or
a groove of an alternate form. Alternately, the present
invention also encompasscs any positioning apparatus in which
the groovc in each arm is converging in form, whethcr the
arms are movable or fixed with respect to each other.
In another aspect, the prcsent invention relates to a
fiber-to-fiber connector formed from con&onting pairs of
positioning apparatus. Such a connector is, in the preferred
instance, disposed in a housing.
2~ In whatevcr embodiment realizcd, it is preferred that the
positioning apparatus be fabricated from a crystalline material,
such as single crystal silicon, using microfabrication techniques.
Each structural element of th~e positioning apparatus (viz., each
of the arms and each foundation) is fabricated in mass on a
wafer of silicon. The finished wafers are aligned,
wo 93/OS415 Pcr/usg2/073s8
7 2116668
superimposed, and bonded, and each of the rcsulting
positioning apparatus se~ercd from tbe finished asscmbly of
bonded wafcrs. Alignment betwcen superimposed wafers is
assurcd using sclected ones of a plurality of alignment grooves
5 on each of the wafers and associatcd prccise di~mcter fibers.
,~
wo 93/05415 rcr/uss2~073ss
2~ C18i
In a most prcferred embod~ment each of the two arms
are divided into two arm scgments, or fingers, to compensate
for slight misalignments of the grooves.
.
! .
~: '
',''~ ,
-
WO g3/0541~ PCr~USg2/07388
9 21I6ii68
BRI~ DESCRIPTION OF T~ DRAW~GS
Tbe invention will be more fully understo~ from~ the
following detailed descripdon thercof, talccn in conncction with
the accompanying drawings, which form a part of this
application, and in which:
Figure 1 is a pcrspecdve, cxplodcd ~riew of a positioning
apparatus in accordance with one embodiment of the present
invention for positioning the center point on the end face of an
optical fiber with rcspect to a predetermined refcrence axis;
lS Figure lA is a definitional drawing illustrating the
characteristics of a convcrging groove as that tenn is used in
this application; -
Figure 2 is a perspective vicw of thc positioning
20 apparatus of Figurc I in thc fully assembled condition;
Figure 3 is a front elcvation Yiew of the assembled
positioning apparatus of ~igures 1 and 2, talcen along view lines
~ 3-3 in Figure 2;
2~
Figure 4 is a sccdonal view, in elevation, of the assembled
positioning apparatus of Figure 2, taken along section lincs 4-4
in that Figure illus~adng the truncated V-groove therein;
Figure 4A is a view generally similar to Figure 4 in which
a full V-groove is formed in the positioning apparatus while
Figure 4B is a view generally similar to Pigure 4 in which both
a full V-groove and a truncated V-groove are formed;
,.~; - , .
WO g3/05415 PCI/US92/07388
.6~6~ 1 o
- Pigure S is a plan vicw one of the arms of the positioning
apparatus of Figurc 1 illustrating thc rclationships of the axes
of thc groovc and thc guidcway thercin;
Figurcs 6A an~d 6B, 7A and 7B, and 8A and 8B are
diagra~ tic c!cvàtional and cnd ~ricws of thc acdon of thc
clips disposcd on the arms of thc posidoning apparatus shown
in Figurcs 1 and 2 in rcsponsc to the introducdon of a ffbcr
thercinto;
Pigurcs 9 and 10 are cxplodcd and asscmblod perspective
views, gcncrally similar to Figurcs 1 and 2, of another altcrnate
cmbodiment of a posidoning device in accordance with the
present invendon in which the arms have nonconvcrging
groovcs therein and in wbich thc arms are articulably movable
with rcspcct to each other along onc axis only;
Figures 11 are 12 are secdonal views taken along section
lines 11-11 and 12-12 in Figure 10;
Figures 13 and 14 are exploded and asscmbled
pcrspccdve vicws, generally similar to Figures 1 and 2, of
anothcr altcrnate cmbodimcnt of a positioning dcvice in
accordance with the prcsent invcntion in which only one of tbe
25 - anns has a nonconvcrging groove thercin and in which both of
thc arms are articulably movable with respect to cach other;
Figures 15 are 16 are sectional views takcn along section
lines 15-15 and 16-16 in Figure 14;
Figures 17 and 18 are exploded and assemblcd
perspecdve views, generally similar to Pigures 1 and 2, of an
alternate embodiment of a positioning device in accordance
with the present invendon in which the arms have converging
WO 93/05415 PCI~/US92/07388
11 21166~8
grooves therdn and in which tbe arms are f,ixed in position
with respect to each other;
Figure 19 is an end view taken along view lines 19-19 in
5 Figure 18;
.. ..
Figure 20 is a side sectional view, talcen along view lines
20-20 in Figure 18, illustradng the position of the fiber within
the channel of the a positioning apparatus in accordance with ',
lO the alternate embodiment of the invention shown therein;
Figure 21 is an exploded isometric view of a pair of
positioning apparatus as shown in Figure 1 used to form a
fiber-to-fiber connector in accordance with the present
15 invention wbile Figure 22 is an isometric view of the fully
assembled conneetor of Figure 21;
Pigures 23 and 24 are, respectively, a top view in section
and a side elevation section view of a pair of posidoning
20 appa~us in accordance the embodiment of the invendon as
shovm in Pigure 17 used to fonn a fiber-to-fiber connector in
accordance with tbe present invention;
Figures 25 and 26 are isometric views of a housing used
2~ for,the fiber-to-fiber connector shown in Pigures 21 and 22 in
the opetl and in the partially.closed posidons, respectively,
while Figure 27 is a section view of the. bousing of Pigure 25 in
the fully closed position taken along section.lines 27-27 of
Figure. 26;
., 30
Figure 28 is a secdon view generally similar to Figure 27
of a housing used for the fiber-to-fiber connector shown in
,:~Pigure 24;
wo 93/05415 rcr/uss2/073ss
~ 2~666~ 12 ` '
Figurc 29 is a isomctric vicw of an alternate housing for a
fiber-to-fiber connector formed of a pair of posidoning
apparatus;
Figurcs 30 and 31 are isomctric cxploded and assemblcd
views, respecdvely, illustrating tbe usc of a pos~doning
apparatus in accordance with the prcscnt invcntion to position
an opdcal ~Iber with rcspect to the axis of an edge cmitdng
active dcvice, in which thc dcvice is surface mountcd;
Figure 31A is a side dcvational vicw generally similar to
Figure 31 showing a positioning apparatus in accordance with
the prescnt invention positioning a lens with respect to an
opto-clcctronic component;
Figurcs 32 and 33 are isometric cxplodcd and assembled
vicws, rcspcctivcly, gcncrally similar to Figurcs 30 and 31,
illustrating thc usc of a positioning apparatus in in accordance
with thc prcscnt in-rcn~ion to posidon an optical fibcr with
rcspect to thc axis of a device having active surface dcvice, in
which the dcvicc is mounted to the cnd of a positioning
apparatus;
Figurcs 34A througb 34F are cnd vicws showing
altcrnatc a¢rangcmcnts of movable arms cach holding a
cylindrical mcmber along at Icast three contact points in
accordance with the prescnt invcntion;
Figure 35 is a perspective view of a positioning apparatus
; 30 havirtg a set of four articulably movable arms in accordance
with an alternate cmbodiment of the present invcntion for
posidoning thc ccnter point on the cnd face of an optical fiber
with respect to a predetermined reference axis, the mounting
foundation being ommitted;
wo 93/05415 PCr/USg2/07388
13 2116G~8
Figures 36A and 36B are an isolated perspecti-ve views of
two of the fingers of the positioning apparatus of Figure 3S;
Figure 37 is a side ele~radon ~iew of the assembled
posidoning apparatus of Figure 35;
Figures 38 and 39 are seedonal views of tbe assembled
posidoning apparatus of Fi~ure 37, respeedvely talcen along
seetion lines 38-38 and 39-39 in Figure 37;
Figure 40 is a top view of the positioning apparatus of
Figure 37 taken along view lines 40-40 therein;
Figure 41 is a side elevadonal view and Figure 42 is a
front elevadonal ~tiew of the assembled posidoning apparatus
with the fingers holting a fiber in tbe centering position, the
: moundng foundation of the posidoning apparatus being
ommitted;
Figure 43 is a: front elevadonal ~iew, similar to Figure 42
illustradng the situadon extant when the finger pairs are
- misaligned, while Pigure 44 is a view illustrating the
misaligned finger pairs bolding a finger in the centering
position; and
Pigure 45 is a perspective ~riew of an enhaneed
positioning apparatus that ineludes the posidoning apparatus of
Figure 35 and further ineludes a elamp rearwardly disposed
therefrom, the moundng foundation of the posidoning
apparatus being ommitted;
Pigure 46 is a perspective view of a wafer used used to
fabrieate a plurality of anns or foundadons used in a
posidoning apparatus in accordance with the present invention;
WO 93/OS415 Pcr/uss2/o7388
1 4
Figure 47 is a perspective view of a mask used in the
photolitbographic proccss fo~ning a plurality of arms or
foundations for a positioning apparatus in accordance with the
present invention~
. ~
Figure 48 is an cnlarged view of a portion of the mask
used for creadng a plurality of arms on the wafer 34;
Figures 49A through 49E are schematic representations
of the process stcps effected during fabrication of the wafer;
Pigure 50 is is an cnlarged view of a portion of the mask
used for creating solder masks on the wafer;
Figure 51 is an enlargcd vicw of a portion of the mask
used for creating foundations on the wafcr;
Figures 52A through 52D are schematic representations
of the steps used to form a plurality of fiber-to-ffber
conncctors from supcrimposed wafers having the arms and
foundations thercon.
WO 93/05415 PCI`/US92/07388
21i6668
Throughout the following detailcd dcscription similar
5 refcrcncc numcrals rcfcr to similar clcmcnts in all~igures--of
tbe drawings.
For purposes of a gcncral ovcrvicw Figurcs I and 2 show
a posidoning apparatus gcncrally by rcfcrcncc character 20 in
10 accordancc with onc cmbodimcnt of thc prcscnt invcntion in
an cxplodcd and in a fully assemblcd condition. Pigures 9 -
through 12 illustrate a positioning apparatus generally
indicatcd by refcrcnce character 201 in accordance with
anothcr cmbodiment, wbilc Figurcs 13 through 16 and Pigurcs
17 through 20 illustrate still altcrnatc cmbodimcnts 202, 203,
respcctivcly, of tbc posidoning apparatus in accordance with
the invcntion. Figure 34A through 34C illustrate yct anotber
al~crnatc cmbodimcnt of a positioning apparatus 204 (having
thrcc ~ns). Figurcs 34D through 45 illUSmltC yet another
altcrnate cmbodimcnt of a positioning apparatus 205 in
accordancc ~vith tbe in~rcntion in wbich thc uppcr and lowcr
arms ha~e bccn subdivided into upper and lower pairs of arm
segmcDts, or fingcrs.
.
Although throughout this application the positioning
apparatus is cast in tcrms of positioning an optical fibcr, it is to
be understood that the prcscnt invcntion may be cffectivcly
utilized with any othcr membcr having the fonn of a small
diameter cylintrical object. By`way of example and not
limitation, the positioning apparatus in acco~dance ~ith the
prescnt invcndon may be used to position a point disposed~ for
example, on the cnd face of a length of microtubing or capillary
tubing. By small diameter it is generally meant less than 0.04
inch (onc (1) miUimeter)?~but usually less than 0.020 inch.
Morcovcr, it should be funbor understood tha~ the term
WO 93/05415 PCI`/US92/07388
16
666a
cylindrical is not to be strictly limitcd to an object having a
completely circular outcr configuradon, but would apply to any
object wbose outcr contour is symmetrical to its ccntral axis.
Tbus, again by~a~y of further examplc and not limitadon, the
positioning apparatus of the present invcntion may_~e uscd to
position a point disposcd, for example, on tbe end facc of a
polygonal sbapcd member or an elliptical membcr.
As will bc devclopcd herein, in thc preferred instance
10 each positioning apparatus in accordancc with tbis invention is
microfabricatcd from single crystal silicon or another
diffcrcntially ctcbablc single crystalline material. Crystalline
materials are prcfcrred bccause tbcy pcrmit the accura~e
formation of tbc structural featurcs of the positioning
15 apparatus in accordancc with the prcscnt invention using the
process of differcndal ctcbing.
Any of the positioning apparatus hercin discloscd is
uscful in accurately placing or accurately positioning a center
20 point on a-fiber, typically a ccntral a~ial point on the cnd face
of the fiber, into alignment with a prcdetermined refercnce
axis and for maintaining the center point in alignmcnt with the
refcrcnce axis. As will be developed this refcrcnce axis itself
may be collinearly aligncd with respect to another axis.
By accurately placing or accuratcly posidoning a ccnter
point into alignment with a predetermincd rcfcrence axis it is
meant that a point, such as a point on the cnd face, of the fibcr
is brought to within a predetermined distance of thc rcfcrcnce
30 axis. This distance is, in general, on the order of a fcw
micrometers (i. e., less than about five micrometcrs) for multi-
mode fibers. ln the case of a single mode optical fiber, a
positioning apparatus in accordance with the prcsent invention
is cspecially adapted for positioning a point of the fiber, such as
35 a point on its cnd face, to within the prccise distance required
.
WO 93/05415 PCI/US92/07388
21166G8
to couple effectively ligbt from the single mode fiber into
another fîber or into an opto-eleetronic device or to eouple
effectively light from a source, as a solid state laser, into the
fiber. This precise distance is even Iess than for multi-mode
5 fibers for eomparable coupling loss. f~
The positioning apparatus in aecordanee with the
invendon is also adapted for positioning a point on the end face
of a multi-mode fiber with respeet to a referenee a~cis.
It should understood tbat the fiber need not be held by
the positioning apparatus at the end face of the fiber in order
to obtain the accurate posidoning of the point on the end face
into alignment with the referenee a~cis. ln pracdee, the
l 5 positioning apparatus contaets tbe fiber a predetermined elose
distanee (on the order of two hundred mierometers) from the
end faee. Contacdng the fiber at a Iocadon rearwardly &om its
end faee impans the eapability to sbut the end face of a fiber
with the end faee of a eonfronting fiber (ss in a eonneetor), or
20 to abut the end faee of a fiber with a eon&ondng surfaee of a
deviee (as in sn eleetro-opdeal eomponent).
In some instances an enhsnced positioning apparatus
may be prwided in order to permit more aeeurate plaeing or
2S more accurate posidoning of the point on the end faee of the
fiber into alignment with respeet to the predetermined a~cis. To
this end, a second posidoning apparatus, spaeed rearwardly
from the first positioning app~aratus, may be used to funedon as
an alignment clamp for the f ber. This arrangement is sccn in
30 Figure 45. Using an enhanced posidoning apparatus, the center
point on the end face of the fiber may be accurately positioned
into alignment with a predetermined reference axis such that
the center point lies within a distance of less than one
micrometer of the reference axis.
wo 93/05415 Pcr/usg2/073s~s
2~666~ - 1 8
If not apparen~ from the foregoing, it should also be
understood that a posidoning apparatus in aeeordanee with the
present invention may be used to aceurately plaee or
aeeurately position: any other point on the eenter a~is of the
5 fiber into alignment with the predetermined ax~
-o-O-o-
As noted, the eylindrieal member preferably takes the
10 form of an optieal fiber. The posidoning apparatus of the
present invendon is pardeularly adapted to plaee a
predetermined point P on the end faee E of an optîcal fiber F
along a predetermined reference axis R. ln pracdce the point P
is the geometric eenter and lies on the axis A of the core C (e. g.,
15 Figures 6A and 68 and Pigures 41 and 42) of the fiber F. The
eore C is itself smrounded by an outer eladding layer L. A
jaelcet J is pro~vided about the eladding layer L but is stripped
from the fiber F prior to the insertion of the fiber into the
posilioning apparatus 20. The jaelcet may eomprise more than
20 one layer. As discussed pre~iously, the dimension of the outer
diameter D of the eladding layer L of the fiber F may ~rary from
fiber to fiber. Typieally this diametrical ~anation~ from ~Iber to
fiber is on the or~er of tluee (3) micrometers. This situation
ma~es diffieult-the posidoning of the point P along the
25- referenee a~cis ;R using the positioning de~riees of the prior art.
-o-O-o-
With reference to Figures 1 and 2 it is seen that tbe
30 embodiment of the positioning apparatus 20 there shown
includes a first and a second arm 22A, 22B, respectively.
Preferably, each of the arms 22A, 22B is identically fo~ned in a
manner to be discussed, so the structural details of only one of
*e anns,- e. g., the ann 22A, will be diseussed. It should be
35 appa~ent, however, that each structural detail of the arm 22A
WO 93/05415 PCI/US92/07388
19 2I1666~ -
finds a counterpart in the otber arm 22B. Accordingly,
corresponding refercnce numerals with tbe appropriate
alphabet suffix will denote corresponding structural details on
the arm 22B. If the arms are not substantially idendcal (as, for
5 examplc, in the embodimcnts of Figurcs 13 thro,~ 16 and
Figure 42) adjustments must be made to providc the requisite
biasing forces to maintain the point P on the refcrence axis R
Thc ann 22A includes a basc portion 24A having a first
10 major surface 26A and a second, opposed, major surface 28A.
The base portion 24A cxtends along the full Icngth of the arm
22A and the dimcnsion of the central rcgion 25A of the base
portion 24A dcfincs the basic dimension of the arm 22A. A
clip gencrally indicatcd by the refcrence charactcr 30A is
15 defined at a first end of thc ann 22A. Thc clip 30A is formed
in a relatively thiclc~r abutment portion 32A that lies on the
first surfacc 26A of thc arm 22A. Tbe abutment 32A has a
planar surface 34A thereon Iha~ prcferab!y lics parallel to the
first major surface 26A. To provide some feeling for the
20 physical dimensions involved, the arm 22A has an overall
length dimension on thc order of twcnty eight hundred (2800)
micrometers and a width on the order of three hundred ~lfty
(350) micrometcrs. In thc central rcgion 25A the ann 22A has
a tbiclcncss dimcnsion on the ordcr of fifty (50) micrometers,
25 while tbe remaining portion of the arm 22A bas a thickness
dimcnsion on the ordcr of one hundred twenty fi~re (125)
micrometers.
As may be better seen with reference to Figures 3 and 4
30 a generally converging V-shaped groove 36A is defined in the
abutmcnt 32A of the clip 30A by generally planar first and
second sidewalls 38A, 40A, respectively, and the forward end
region of the first surface 26A of the base 24A. The sidewall
38A has an upper edge 39A (Figure 1) thereon while the
35 sidewall 40A has an upper edge 41A thereon. It should be
wo 93/05415 Pcr/uss2/073ss
666Y~ 20
understood that the tcrm "planar" is mcant to encompass a
surfacc formcd in a singlc crystal matcrial by etching in which
microscopic steps are of necessity produced owing to the lattice
structure of the crystal.
Witb reference now to thc definitional drawing of Figure
IA, the meaning of the term "convcrging" wben applied to a
groove in any embodiment of thc invention herein disclosed
(using the rcfcrence charactcrs of Figures 1 and 2) may bc
10 made more clear. As uscd herein, a "converging" groove is a
groovc 36 dcfincd from at least two planar sidewalls 38, 40
and has an enlarged inlet cnd 42 and a narrower outlet end 43.
The respective upper edges 39, 41 of the sidewalls 38, 40 of
the groove 36 lie in a reference plane RP having a reference
15 axis R Iying therein. Tbe planar surfaces 34 also lie in the
refcrcnce plane RP. The reference axis R extcnds in the
refercnce plane RP from the inlet end 42 to the the outlct end
43 of ~c groove 36. Each point on the refercnce axis R is
spaced in the reference plane RP an equal perpendicular
20 distance from the respecdve upper cdges 39, 41 of the
sidewalls 38, 40. The distance between the upper edges of the
sidewalls and the axis R decreases from the inlet end 42 to the
outlcl end 43 of the groove 36.
The surfaces of the sidewalls 38, 40 are equally and
oppositcly inclincd with respect to the reference plane at an
angle A grcatcr than zero and Icss than ninety degrees. The
angle of inclinadon A is determined by the latdce structure of
the crystal, and in the case of (100) silicon, is 54.74 degrecs.
The projections of the sidcwalls 38, 40 intersect in a line L that
itself intersects the reference axis R forwardly past the outlet
end 43 of the groove 36. Tlhe line L is inclincd with respect to
t}~.e reference plane RP at an angle B that is greater than zero
degrees but less than ninety degrees. In the reference plane
35 RP thc upper cdgcs 39, 41 of the sidcwalls 38, 40 cach
wo 93/05415 Pcr/uss2/073ss
21
- 2116668
eonverge toward the referenee axis R at an angle C that is on
the order of two and one-half to five degrees (2.5 to 5) degrees,
and most preferably at about three (3) degrees. The angle B is
dependent upon the values of the angles A and C and typically
5 the angle B lies in the range from about fo0 (4),~ve ~5)`
degrees. As used berein a "fully funnel-lilce" ehannel is a
ehannel that is defined by the cooperative assoeiation of at
least two eonverging grooves. A "partially funnel-lilce" channel
is a ehannel that is defined by one eonverging groove and a
1 0 surface.
From the foregoing it may be readily understood that a
"uniform width" groove is one in which each point on the
referenee axis R is spaced in the reference plane RP a uniform
15 distanee from the edges 39, 41 of the sidewalls 38, 40 as one
progresses from the inlet end 42 to the outlet end 43 of the
groove 36. The sidewalls of a uniform width groove may be
inelined with respeet to referenee plane RP, or they may e~ctend
perpendieularly to it, as desired. A channel fonncd from one
20 or two uniform width groove(s) is termed a "uniform width"
ehannel. Sueh a ebannel may have a rectangular eross seetion
in a plane perpendieular both to the referenee plane and to the
referenee axis, assuming no inelination of the sidewalls of the
groove.
- A tapering groove is one in whieh the planar sidewalls
are perpendieular to the referenee plane but the distance in the
referenee plane between the referenee axis and the edges of
the sidewalls deereases as one progresses from the inlet to the
30 outlet of the groove sueh that the extensions of the planar
sidewalls intersect in a line that itself interseets
perpendicu1arly with the reference axis.
ln the embodiment seen in Figures 3 and 4 the groove 36
35 is a eonverging groove, and more preferably, is a V-groove
WO g3/OS415 PCl~/US92/07388
22
6 Iruncated by the presence of third sidewall defined by a
portion of the major surface 26 of the arm 22 in which it is
disposcd. The truncated V-groove bas the same depth
throughout its lengtb, when measured along a dimension line
5 erected pcrpcndicular to tbc surface 34A of the, ~utment 32A
in a direction extending toward tbe ma~or surfacc 26A~
It should be understood that tbe V-shape of the groove
36A may take alternatc forms and rcmain within the
10 contempladon of the invendon. For example, as seen in Figure
4A, the groove 36A may be defincd by only tbe first and
second sidewalls 38A, 40A, respectivcly, in which cvent the
groove 36A appears as a full V-shape throughout its length.
Thc apcx 42A of thc groovc 36A thus appcars throughout the
15 full length of the groovc 36A.
Figure 4B shows another alternative arrangement in
which a truncatcd V-groovc (dcfincd by thc first and second
sidcwalls 38A, 40A, respectivdy, and the portion of ~he major
20 surface 26A) extends for some prcdetermincd axial distance
while a &ll V-groove (defined by the first and second sidewalls
38A, 40A, rcspectivcly) extcnds for some sccond
predetermined distance. Thus, as scen in Figurc 4B, when
measured along a dimension line erccted perpendicular to the
25 surfacc 34A of the abutment 32A in a direction extending
toward tbe major surface 26A the dcpth that the groove 36A
extends into the abutmcnt 32A is greater at its inlet end 42 (as
indicated by the dimension arrow 44A) than it is at its outiet
cnd 43 (as indicated by the dimension arrow 46A).
The fully truncated V-groove shown in Figure 4 is
preferred for the embodiment of Figures 1 and 2. For purposes
of ease of manufacturability, as will be made clear herein, it is
also preferred for the embodiment of Figures l and 2 that the
35 groove 36A does not converge throughout the full axial
wo 93/05415 Pcr/usg2/073a8
23 2116668
distance through the abutment 32A. Owing to the provision of
tabs 48A, 48B (Pigurcs 1 and S) formed near the ends of the
abutments 32A, 32B, the sidewalls 38A, 40A dcfining the
groove 36A do not converge throughout the full Icngth of the
5 groove, but dcfine a short uniform width portion ~st past the
convcrging portion of thc groove 36A. Tbe ovcrall axial Icngth
of thc groove 36 (including both tbc converging and thc
uniform width portions) is on the ordcr of three tenths (0.3) of
a millimeter, while the uniform width portion of the groove
lO occupies an axial length of one tenth (0.1) of a millimctcr. As
is believcd bcst seen in Figure S the converging and
nonconverging portions of thc groove 36A have a common axis
50A associated ~hcrewith.
Again with reference to Figure 2, an extended
enlargement region 54A having a planar surface 56A lics on
the basc portion 24A of the arm 22A spaced a predetermined
axial distance 58A behind the abutmcnt 32A. Thc distance
58A is on thc order of one (I) millimeter. The surface S6A is
20 coplanar with the surfacc 34A. The enlargement 54A is
provided with a nonconvcrging, uniform width, truncated V-
shaped trough 60A dcfined by inclincd planar sidewalls 62A,
64A, respecti~dy, and by a portion of the major surface 26A of
the base portion 24A ncar the second end thereof. In the
25 cmbodimcnt shown in Figures I and 2 the trough 60A is
uniform in depth along its axial length, as measured with
respcct to a dimcnsion line erected perpendicular to the
surface 56A toward the major surface 26A. The trough 60A
communicates with a convcrging lead-in 68A. If desired, the
30 walls 62A, 64A may be inclined with respect to each otbcr so
that tbe trough 60A may be a full V-shape or a partial V-
sbape, similar to the situation illustrated in connection with
Figures 4A and 4B for the groove 36A. Alternatively, the walls
62A, 64A defining the troughs 60A, 60B may be parallel or
35 otherwise conveniently oriented with respect to each other. As
WO 93/0541s Pcr/us92/07388
666Q~ - 24
is bclievcd best seen in Figure S the trough 60A and the lead-
in 68A havc a common a~us 70A. Thc length of thc trough 60A
and associated lead-in 68A is on tbc ordcr of l.S9 millimetcr.
.
Figurc S is a plan view of onc of thc arms 22A; In thc
prcfcrrcd implemcntadon of thc cmbodimcnt of ~Figurcs 1 and
2 thc axcs SOA, 70A (rcspectivcly through the groovc 36A and
tbc trough/lead-in 60A/68A) are offset a predetermined
distancc 72 in the refcrence plane RP (the plane of Figure S).
Prefcrably, thc offsct 72 is at Icast one-half the diffcrcnce
bctwccn the diamctcrs of the andcipated largest and smallest
fibcrs to be posidoned. As will become clea~er herein
offsctdng the axes SOA, 70A of the structures 36A, 60A/68A
facilitates thc ccntering acdon of the positioning apparatus 20
by insuring that a fiber, as it is introduced into thc apparatus
20, is biased to stril~c one of ~he sidcwalls 38A, 40A forn~ing
the groo~re 36A (and analogously, tbe sidewalls 38B, 40B
f~nming tbe groove 36B). Tbis insures wall contact with tbc
fiber at at Icast two spaced locadons. Howe~rcr, the prcsence of
the offsct 72 ncccssitatcs addidonal manufacturing
consideradons, as will bc discussed. It should bc notcd tbat tbe
forcc rcsulting from Uasing tbe fibcr in the manner just
discussed (or the forcc on ~hc fibcr due to gravity) is much
smallcr in magnitude than the biasing force of tbe arms wbich
servcs to ccntcr the fibcr on the rcferencc-axis. ~
ln tbc asscmblcd condition the arrns 22A, 22B are
disposed in supcrimposcd relationship one above the othcr,
with the groovc 36A, the troùgh 60A and the lead-in 68A on
the one arm 22A rcgistering with the corresponding groo~e
36B, trough 60B and lead-in 68B on the other arm 22B. The
rcgistcrcd con~rerging groo~res 36A, 36B in the abu~ments 32A,
32B cooperate to define a generally fully funnel-shaped
channel 92 having an input end 94 (Figure 4) and an output
35 cnd 96 (Figures 4 and S). (Note that if the tabs 48 are
wo 93/05415 Pcr/uss2/073ss
2116668
providcd, the channcl 92 so defined has a uniform width
portion just preccding the outlet end 96 thereof.) The
rcfcrcncc axis R extcnds ccntrally and axially through the
channcl 92. The rcfcrence alcis R lies on thc interscction of the
5 rcfcrcnce planc RP (which contains the conjoined su.rfaccs 34A,
34B) with the phne cont2ining the axes SOA, 50B of the
convcrging groovcs 36A, 36B.
The registered troughs 60 and lead-ins 68 cooperate to
10 define a guideway 98 (Figure 2). Similarly, the axis R' through
~he guidcway 98 lies on the intersection of the plane containing
the conjoined surfaccs 56A, 56B of the cnlargements 54A, 54B
(which is the refcrcnce plane in the preferred case) with the
planc containing the axcs 70A, 70B (Figure 5) of the
15 troughllcad-in 60A/68A, 60B/68B. Thc axcs R and R' both lie
in the rcfcrence planc RP (the plane of the surfaces 34A, 34B,
56A, 56B) although thc axcs R and R' are laterally offsct with
rcspect to cach other in this rcfercnce plane by a
prcdctermined offsct distance 100 (Figure 1). For a fibcr the
20 offsct distance 100 is typically on the order of five (5)
micromctcrs.
Tbe inlct cnd 94 of the fully funnel-like channel 92 (bcst
secn in Figurcs 4 and 5) is sizcd to circumscribe and thereby to
25 accommodate a fibcr F whose cladding laycr L (or outsidc
surfacc) has the largest cxpected outer diameter dimension.
The outlct cnd 96 of thc channel 92 (best secn in Figure 3) is
sized to circumscribc and thcrcby to accommoda~e a fiber F
whosc cladding laycr L (or outside surfacc) has a dimension
3~ somcwhat smaller than the minimum cxpcctcd outer diameter
dimcnsion of the fibcr F. ln practice, to position an optical
fibcr having a nominal outer diameter dimension of one
hundrcd twcnty fivc (125) micromcters, the largest cxpected
outer diamctcr dimcnsion is on the order of one hundred
35 twenty ninc (129) micrometcrs while the smallcst cxpcctcd
.. . . .. . . ...
Wo 93/OS4lS Pcr/u~s92/073~8
26
~666~
outer diameter dimension is on the order of one hundred
twenty one (121) micrometers.
The dimension~ of each of the troughs 60A, 60B is such
S that the guideway 98 so formed by the registered troughs 60A,
60B is sized to accommodate a fiber F whose eladding layer L
has the largest expected outer diameter dimonsion. Despite its
dimension with respect to the fiber, the guideway 98 assists in
the insertion of a ffber into the positioning apparatus 20 and is
10 advantageous in this regard.
ln the embodiment shown in Figures 1 through 5 the
surfaces 34A, 34B on the respective arms 22A, 22B,
respeedvely, are, when in a first, closed, position, either in
15 eontaet with each other or, if desired, within a predeterrnined
elose distance to each other. Por optical fibers the
prede~rmined close distanee is typically on the order of five
(5) to twenty-five (25) micrometers. In this embodiment the
planar surfaces 34A, 34B on the abutments 32A, 32B of the
20 elips 30A, 30B are not secured to each other and may move to
a seeond, ce~tering, posidon, as will be described. The planar
surfaees 56A, 56B on the respecdve arms 22A, 22B are secured
to each other by any convenient means of attachment, as by
fusing or soldering. It should be understood that any other
25 meehanieal securing expedient may be used to attach or
olerwise hold together the surfaees 56A, 56B to each other.
Tbe positioning apparatus 20 further ineludes a mounting
foundation 74 (Pigures I and 2). The moundng foundation 74
30 is provided with a planar attaehment surfaee 76 thereon. A
step 78 in the mounting foundadon 74 serves to space the
attachment surfaee 76 a predetermined clearanee distanee 80
from a second surfaee 82. The opposite major surface, e.g., the
surface 28A, of the arm 22A is seeured, as by fusing or
35 soldering, to the planar attachment surface 76 on the
:
WO 93/054~5 PCI`/US92/07388
27
211 66G8
foundation 74. Of eourse, it should be again understood that
any alternative meebanical attaebment expedient may be used
to attaeh or otherwise hold together the seeond major surfaee
of the arm to the foundation 74.
' .
Altbough the seeond surfaee 82 of the foundation is
shown in the Figures as being generally planar in the preferred
ease, it should be understood that this surface 82 may take any
desired eonfiguration. As will be more fully appreeiated
10 herein, so long as the opposite surfaee 28A of the arm 22A
affixed to the foundadon 74 is, at least in the region of the elips
30A, spaced at Ieast a predetermined clearance distance 80
from the second surface 82 (assuming the surface 82 is parallel
to the surfaee 76), the movement of the clip on the arm 22A
15 attaebed to the foundadon (in the drawings, the elip 30A) to be
deseribed will not be impeded.
When assembled, the elips 30A, 30B disposed at the ends
of the arms 22A, 22B, respeedvely, are supported in a
20 eantile~rered fashion from the eonjoined enlargements 54A, 54B
at the opposite ends of tbe arms. The arms 22A, 22B are ~igid
in x-z plane, as de~med by the eoo~dinate axes shown in Figure
1. Moreover, the relatively ~hin dimension of the eentral
region 25A, 25B of tbe base portion 24A, 24B of the arms 22A,
25 22B axially intermediate the respeetive abutments 32A, 32B
and the enlargements 54A, 54B aets as a flexure and permits
each anrl 22 to flex, springboard fashion, in the direetions of
the arrows 88 in the y-z plane. As used herein it should thus
be appreeiated that a flexure is a spring member that is rigid in
! ' 30 one plane and is eonstrained to flex in the orthogonal plane.
lt should further be appreeiated that when a clip 30A,
30B is defleeted in its corresponding respeetive direction 88A,
88B, the resilieney of the thinner central region 25A, 25B of the
35 base 24A, 24B, aeting as a flexure, defines means for biasing
WO 93/05415 PCI`/US92/07388
~666~ 28 `
the clips 30A, 30B toward tbe first, closed, position. The
biasing force acts on the clip 30A, 30B in a direction shown by
the arrows 90A, 90B, countcr to the direction of motion 88A,
88B of the arms. The biasing forccs must be substantially
5 equal and in opposite directions. In general, whatever the
number of arms used in the positioning apparatu~, the force on
each arm passes through the refcrcncc a~cis and the sum of
forces wben in the centering position substantially equals zero.
Biasing means cmploying the thinncr central region of the base
10 24 as a flexure (as shown in the Figures I to 4) is preferred for
all discloscd embodimcnts, bccause when implemented in a
single crystal material using a microfabrication technique
precise control of the biasing forces is able to be attained.
Typically the bias force on each arm is on the order of five (5)
1 5 grams.
It should be understood that any other convenient
mecbanism may bc used to define the means for biasing the
arms and the clips 30 thereon toward the closcd posidon so
20 long as tbe fo~ce on cach arm passes through the reference axis
and the sum of forces on the arms when they are in the
centcring position is substantially equal to zero. Whatever
form of biasing means is selected the bias force must increase
with deflection of the arm.
-o-O-o-
Having dcfined the structure of the positioning apparatus
20 of the embodiment of Pigures I and 2, the operation thereof
30 in positioning a point P on the center axis and on the end face E
of an optical fiber F along a predetermined reference axis R
may be readily understood in connection with Figures
through 7.
wo 93/05415 PCr/USg2/07388
29 21166~8
ln operation thc fiber F is inserted into tbe positioning
apparatus 20 in the dircction of thc arrow 102 (Figure 6A).
Tbe Icad-in portions 68A, 68B (Figure 1) cooperate to guide the
fibcr F into thc guidcway 98 (Figurc 2) defined by thc
5 rcgistcrcd troughs 60A, 60B in tbc cnlargcmcnts,.~A, 54B
(Figurc 1). Becausc the axis R' of the guidcway 98 is offsct
from tbe axis R of thc fully funnel shaped cbannel 92 thc
guidcway 98 scrvcs to guide thc facc E of the fibcr F toward
tbc inlct cnd 94 of tbc channel 92 at a predetermincd azimuth
10 with rcspcct to tbc a~is R.
As a rcsult the cnd face E of the fiber F enters the
channcl 92 and is inidally displaccd, or movcd, through contact
with at Icast one of tbe sidcwalls 38A or 38B, 40A or 40B (or
15 portions of thc major surfacc 26A, 26B, if these are uscd to
dcfinc thc groo~cs 36A, 36B, as in Figure 4) on one of the clips
30A, 30B, respccd~cly, to thc cxtcnt nccessary to move a
prcdctcrmincd point P on an end facc E of tbe fibcr F toward
alignmcnt with thc rcfcrcncc axis R.
At somc point on thc path of axial insertion of thc fibcr F
into thc channcl 92, as the cnd E of thc fibcr F movcs toward
- thc oudct cnd 96, thc outcr diamctcr of thc cladding layèr L of
thc. ~Iber P cxceeds tbe dimcnsion of thc channcl 92. Thc arms
25 22A,~-~2B rcspond to a forcc in the dircctions 88A, 88B imposcd
-thcrcon by the fiber F by mo~ring against thc biasing forcc from
the first, closcd, position, shown in Figures 7A, 7B, toward a
second, ccntering, posidon sho~wing in Figures 8A, 8B. In the
ccntcring position thc clips 30A, 30B open against thc bias
30 forcc acting in thc dircctions 90A, 90B generated by the flcxing
of tbc arms 22A, 22B, to separate the surfaces 34A, 34B
thcrcon. Howcvcr, this movement of the arms 22A, 22B from
tbc first toward the sccond position positions the point P on the
cnd face E of the fibcr F on the reference axis R. The cnd face E
35 of the fiber F thus cxits through the outlet end 96 of the fully
WO 93/OS415 PCI`/US92/07388
666Q~ 30
funnel shaped channel 92 with tbe point P preeisely aligned
witb (i.e., witbin one mierometer of) tbe reference a~cis R, as is
shown in Figures 8A, 8B. Tbe fiber F is beld in tbis position by
eontaet with tbe sidewalls 38A, 38B, 40A, and 40B.
If the tabs 48A, 48B are formed on the abutments 32A,
32B these tabs eooperate to define a passage of unifonn width
along its axial lengtb tbat eommunieates with the outlet of the
funnel-lilce ehannel. The fiber F passes tbrough and emerges
10 &om sueh a eonduit with the point P on tbe end face of the
fiber sdll along the referenee axis R.
lt should be noted that the movement of the arms could
be other than the flexing thereof as deseribed heretofore. It
15 therefo~e lies witbin the eontempladon of this invention to
have the arms mo~e in any other manner, as, for example, by
any fonn of pinned or jointed (ardeulated) modon.
- o -O-o -
With referenee now to Figures 9 through 12 an alternate
embodiment of the posidoning apparatus 201 in aeeordanee
with the present invendon is shown. In this embodiment the
arms 221 are, similar to the embodiment earlier diseussed,
25 artieulably~mo~rable~in eantilevered fashion with respect to
eaeh other against the bias of the flexure defined by the eentral
portion 25l thereof. However, ~e grooves 36t formed in the
arms 22l are not eonverging grooves, but are uniform width
groo~es. Aeeordingly the chànnel 921 formed by the
30 eooperadve associadon of the arms 22l when superimposed
one on the other is a uniform width channel. The maximum
dimension of sueh a channel 92l in the plane perpendicular to
the reference R is less than the outside diameter of the smallest
antieipated fi~ber F.
Wo 93/05415 Pcr/usg2/o7388
31 2I166~8
A further modification to the positioning apparatus 201
may bc sccn from Figure 12. It is first notcd that the planar
walls 621, 641 of the troughs 601 are parallel, rather than
inclined with rcspcct to cach othcr. Morcover, the offsct 100
bctwccn the axcs R and R' lics in thc vcrtical plane,:that~is, in
thc planc containing the axcs 701 of thc troughs 601, as
opposcd to bcing offsct latcrally (i.c., in thc plane containing
the surfaces 561). The lead-in portions 681A, 681B are
ommittcd here but may bc providcd.
In operation, a fiber F is inscrtcd into the positioning
apparatus 201 and guidcd by the passage 981 defined by the
registcred troughs 601A, 601B. Bccause the axis R' cf the
passage 981 is vcrtically offsct from the axis R of the channel
lS 921 thc surface 261B of thc arm 221B bounding the passage 981
scrvcs to guide thc fibcr F toward thc inl~t cnd 941 of the
channcl 921. Thc fibcr P enters thc channcl 921 and contacts
witb the cdgcs of the sidcwalls 381A, 381B, 401A and 401B.
Duc to dle sizing of the groo~rcs 36tA, 36)B the fiber F docs not
touch thc major surface 261A, 261B of the arms 221A, 221B,
rcspectivcly. The fiber may be chamfcrcd or tapcred or a
mecbanical device may be uscd to facilitate insertion of the
ber into the channel 921.
.
Since thc fiber F cxcecds the dimension of the channcl
921 thc clips 301A, 301B arc displaccd from the first, closed,
posidon toward a second, ccntcring, position. This movcment
of the clips 301A, 301B maintains the point P on the end face E
of thc fiber F on the rcference a~is R. The end face E of the
fiber F thus cxits through the outlet end 961 of the channel 921
with the point P precisely aligned on the reference axis R. The
fiber F is held in this position by contact with the edges of the
sidewalls 381A, 381B, 401A, and 401B, as indicated by the
character LC.
wo 93/05415 Pcr/uss2/073ss
?,~666~ 32
-o-O-o-
The cmbodimcnt of the positioning apparatus 201 shown
in Figurcs 9 to 12 can be furthcr modified, as seen by the
5 positioning apparatus 202 shown in Figures 13 to,~l6; In this
modification, thc arm 222B differs from those shown carlier in
that no groove is provided thcrein (Figure 15). In this
cmbodiment, if the groove is a converging groove, a partially
funnd^lil~e channd is dcfincd. The fiber F is guided ~y contact
10 against the major surfacc 262B and held in posidon on thc
rcference a~cis R by contact with the major surface 262B and
the edges of the sidcwalls 382A, 382B. again as indicated by the
charactcr LC.
1 5 -o-O-o-
Figures 17 and 18 are cxploded and assembled
pc~spectivc views, gcncr:ally similar to Figures I and 2, of
anothcr altcrnatc embodimcnt of a positioning apparatus 203 in
20 accordance with thc prosent invcntion while Figurc 19 shows
thc end view~ thaeo In this embodimcnt, instead of the arms
bcing articulably movablc as dcscribcd carlicr. the arms ~re
~lxcd rclativc to cach other. Each of the arms 223A and 223B
has a con~rerging groovc thercin and the channel 923 formed
25 by thc coopative association of the arms 223 when
supcn nposed one on the othcr is fully funnel-like in form.
Thc channcl 923 dcfincs a minimum dimension in the plane
perpendicular to the reference~ R that is. near its outlet cnd, lcss
than thc outside tiameter of the smallcst anticipated fibcr F.
3 0
In operation, a ~Ibcr F is inserted into the positioning
apparatus 203 and guided through the passage 983 toward the
inlct end 943 of thc channcl 923. l"he fiber P entcrs the funnel-
liko channel 923 and is guidcd by contact with one or more of
35 ~he sidcwalls 383A, 383B, 403A and 403B and/or major
'-`'-';
wo 93/054lS rCr/USs2~073s~
33 2116668
surfsces 263A, 263B to place tbe point P of the fibcr F on the
a~cis R. Howevcr, sincc the arms 223 are fixed with rcspect to
cach otbcr, tbc fibcr F can only advance within the channel 923
to tbc xial location wbcre tbe outcr diametcr of the fiber F
5 equals tbe local d mcnsion of thc cbannel 923. ~this a~cial
locat on within the cbanncl tbc fiber is held in posidon by a
minimum of four point contacts (indi~atcd by the characters
PC) bctween thc fibcr F and cacb of thc sidewalls 383A, 383B,
403A, and 403B. ~hc dimcnsion of the channel is such that the
10 fibcr is not ablc to contact the major surfaces of the arms 223
when it is held along thc rcfercnce axis R. Figure 20 illustrates
the ffber as thc same is hcld within the channe' 923 Thc axial
spacing 104 bctween the cnd facc E of the fiber F and the
outlct end 963 of the channcl 923 varies, dependent upon the
15 nuter diameter dimcnsion of thc fibcr P.
-o-O-o-
The positioning ~pp~ratus 20, 201. 20~ and 203 in
20 accorda~ee with any of thc above-dcscribcd embodimcnts of
thc invcntion may be uscd in a varicty of applications which
requirc the precise posidoning of a point P on the cnd face E of
a fibcr F along a refercnce axis R.
ln Figurcs 21 and 22, a pair of positioning app~atus 20-
1, 20-2 (corresponding to the embodimcnt shown in Figurcs l
and 2) are arran8ed to define a fiber^to-fiber conncctor
generally indicatcd by the reference character 120. In this
a,rrangcm~nt the apparatus 20-1, 20-2 are confrontationally
disposcd with rcspcct to the other so that the outlet ends ~6 of
the rcspective channcls 92 therein are spaced a predetermined
distance 122 with the respective reference axes R therethrough
being collinear. To effect such an arrangement the foundation
74 is cxtcnded in an axial direction and each axial cnd thereof
is provided with a planar attachmcnt surface 76. Each
WO g3/05415 1'Cl/US92/07388
34 `
~666~
positioning apparatus 20-1, 20-2 is mounted to its respeetive
at~aehment surfaee 76.
. .
Tbe fibers F-l and F-2 to be conneeted are inserted into
5 the Iead-ins 68 of tbe respeetive positioning app~us 20-i,
~0-2. Eaeb positioning apparatus 20-1, 20-2, aeting in the
manner deseribed above, serves to plaee the point P on tbe end
faee E, of the respeetive fiber F-l or F-2 along tbe eollinearly
disposed a~ces R. The fibers F-l, F-2 are inserted in to the
10 respeetive apparatus 20-1, 20-2 until tbe end faees E on eaeh
fiber abu~. The ends E of tbe fibers F-l, F-2 are seeured due to
the abo~re-deseribed holding aetion of the positioning
appar2t~s. If desired an suitable index matching adhesive,
sueh as an ultraviolet euring adhesive sueh that manufactured
15 and ~old by Eleetro-Lite CoFporation, Danbury, Conneetieut as
number 820t)1ELC4480, may be used.
It shoold be understood that the fiber-to-~lber eonneetor
may be implemented using any of the other of the above-
20 diseussed alter~adve embodiments 201, 202, and 203 of thepositioning apparatus. In the event a pair posidoning
apparatus 203 as shown in Pigure 17 is used ~see Figures 23
and 24), the eonfronting ends of the positioning apparatus 203-
1, 203-2 are preferably abutted and secured, or the pair of
25 positioning apparatus formed integrally with each other. The
spaeing 122 between~the end faces E of the ffbers F-l, F-2 is, in
this embodiment, defined by the sum of the distances 104-1,
104-2. The spaeing 122 is filled with an index matehing
n~aterial, sueh as the adhesive defined abo~e. To this end, an
30 aceess port 124 is provided to permit the introducdon of the
index matehing material into the region between the
confrondng end face of the fibers F-l, F-2.
Prior to inserdon into the posidoning apparatus (of
35 whateYer form) it sbould be understood that the jacket J
" ,~ -
Wo 93/05415 Pcr/uss2/07388
35 2116668
(Figure 29) of the fiber F is stripped in its cntirety a
predctcrmined distance ~rom the frce cnd thereof. The
exposed portion of the fiber is clcaned with alcohol. The fiber
is clcavcd to form tbe end face E. If desired the cnd face E may
S be ground into a convcx shape to yicld a point o~be Iensed.
-o-O-o
If desired the fiber-to-fibcr connector 120 may be
10 disposcd in a suitable housing 130 (Figure 25). The preferred
form of the housing 130 is generally similar to that disclosed in
United States Patent 4,784,456 (Smi~h), assigned to the
assignee of the prcscnt invcntion. This patcnt is hcrcby
incorporatcd by rcfercnce hcrcin. The housing 130 includes a
15 basc 13~ and a cover 134. The basc 132 is, in all cases,
providcd with a recess 136 that is sized to closely receive the
connector 120. If thc connector 120 is realized using any form
of th~ positioning apparatus that articulatcs, the cover 134
must bc providcd with a corresponding recess 138 locatcd so
20 as to pcnnit the aniculadng motion of thc arms of posidoning
apparatus used to form thc connector. If the conncctor 120 is
rcalizcd using thc form of the positioning apparatus shown in
Figurcs 23 and 24, the secess 138 need not be pro~ridcd. Such
a housing 130 is sho~vn in Figure 28.
Tbe cover 134 is segmented into three sections, 140A,
140B, 140C, cach which is hingcd to the base 132. The base
132 has, adjacent to cach cnd of the rcccss 136, V-shaped
groovcd ~egions 142A, 142B. The top end sections 140A, 140B
30 each contain respective gcncrally tapered lands 143A, 143B.
Each of the lands has serrations 145A, 145B respcctively
thcreon.
ln usc a conncctor is inscncd in thc recess 136 of the
35 housing 130. It is thcre hcld in place by friction but may be
WO 93/05415 PCI`/US92/0738~8
~666 36
otherwise secured if desired. The central section 140C of the
cover may then be closed, if desired. An optical ~Iber having a
predetermined length of its jaclcet J stripped and cleaned, is
inserted tbrough~ oDe of the V-shapcd grooved regions 142A,
5 142B to dispose thc stripped cnd of the fiber int,o~he connector
120. Tbc groovcd rcgion serves to propcrly oricnt and posidon
the ~Iber with respect to the conncctor t20 in the rccess 136.
The associated top cnd section 140A, 140B, as the case may be,
is thcn closed and latched to the corresponding portion of the
10 base 132 (Figure 25, with the fiber ommittcd for clarity).
When the top is secured to the base the serrations 145 act
against the jacket of the fiber to urge, or to bias, the fiber
toward the connector. A second fiber is correspoDdingly
introduced into the housing and connector in an analogous
15 manncr. If not alreadv done so, the central section 140C of the
covcr is then closcd. The housing 130 is preferably formed by
injection molding.
As sccn in Figure 29, in another form the housing 130
20 may bc implementcd using a mass 160 of index matching
material, such as that idendfied above. The mass 160 extends
ovcr both the conncctor i20 ~to embed the same thcrein) and
some prcdetermine.d portion of the jackets J of the fibers F-l,
F-2.
- o-O -o -
The reference axis R on~which the point P of the fiber F is
positioned may itself extend collinearly with the axis X of any
! ~ 30 of a ~raricty of dcvices. Accordingly, a positioning apparatus 20
may be used to accurately position the point P on the end face
E of the fiber F with respect to the axis ~C of a particular device
170. Figures 30, 31 and Figures 32, 33 illustrate several
cxamples of the use of a positioning apparatus 20 to locate a
35 fiber F along an axis X of a device 170. The device 170 may,
~W0 93/0~415 rCI'/US92/07388
37 2116668
for example, be realized by any aedve optieal eomponent, such
as a solid state laser, a photodiode, a light emitting diode,
whether these deviees are edge aeti~re deviees or surfaee active
deviees. Although in the diseussion that follows the reference
5 ebaraeter 20 is used to indieate the positioning ~ppi~ratus, it
should be understood that any one of the embodiments of the
positioning apparatus 201, 202 or 203 heretofore deseribed may
also used.
When used in eonneetion with an edge aetive deviee 170
the a~rangement in Figures 30 and 31 is preferFed. In this
arrangement the foundation 74 is axially extended to define a
pedestal 174 at the axial end thereof. Tbe upper surface 176
of the pedestal 174 defines a planar attaehment surfaee. Tbe
lS surfaee 176 is spaeed a predetermined distanee above the
attaehment ~urfaee 76 or otherwise loeated sueh that when the
ed~e opdeal eomponent 170 is mounted the surfaee 176 tbe
axis X of the de~iee 170 and the referenee axis R are eollinear.
With the a~ces R and X eollinear, the posidoning of tbe point P
20 on tbc fiber F along the axis R will automatieally posidon that
point P in the same relationship with the a~is X. The deviee
170 must be aeeurately mounted on the surfaee 176 so that its
axis X is eollincatly aligned with the axis R.
To mount the deviee 170 the surfaee 176 may be
pro~rided with a layer of solder layer, sueb as a gold/tin solder.
The de~iee 170 may have a eorresponding layer of tbe same
material. The de~iee 170 is positioned on the surfaee 176
using a suitable mieroposidoning a~pparatus, sueh as a ~raeuum
probe. The de iee is aligncd to the edge, heated above the
melting point of the solder and cooled, so that the solder forms
a bond.
When used with a surface active deYice, as seen in
35 Figurcs 32 and 33, ~e aetive surface of the device 170 is
WO93/OS415 PCT~US92/07~
666~ 38
sccured to the front surface 178 of the pedcstal 174. Attaching
the dc~icc to the front surface 178 iS bclicvcd to pro~ride
suffieient bonding area to securc thc dcvicc 170 to the
positioning apparatus 20. The surface 176 Of thc pcdcstal 174
5 is rclie~ed to avoid obstruction betwecn the actiyc.region Of
the device 170 and the cnd face E of thc fibcr P~
It should also bc appreciated, as is illustrated in Pigure
31A, that thc positioning apparatus in accordance with any one
10 of thc embodimcDts herctoforc dcscribcd may bc configurcd to
accuratcly position a Icns, such as a ball or a rod lens L, with
rcspect to thc axis X of thc dcvicc 170 (whcther tbe samc is an
cdgc acdvc or a surfacc aetivc dcvicc). The posidoning
apparatus would bc modified to providc a seat 31S in tbc clips
15 30 thcreof sizcd to acccpt tbc Icns L.
-o-O-o-
ID addidon to thc ~arious cmbodimcDts of thc two-anned
20 eoDfiguradoDs for the posidoning apparatus 2Q 201, 202 and
203 of thc prcscnt inwntion prcvioudy discloscd, it lics within
tbc coDtcmplation of this in~rcndon for a positio~ng apparatus
in aceordancc with this in~cndon to cxhibit morc than two
arms 22.
ID this regard Pigurcs 34A to 34C gcnerally illustratc a
posidoDiDg apparatus 204 ha~ing tbrcc arms 22A, 22B and 22C.
Figures 34D through 34F gcncrally illustratc a
30 positioning i apparatus 205 having four anns 22A, 22B, 22C and
22D. A detailcd description of an embodiment of a four armcd
posidoniDg apparatus 205 is sct forth hcreinafter.
The cxtension to c~cn grcatcr numbcr of arms would bc
35 readily apparcnt to thosc s~illed in thc art.
WO 93/05415 PCI~/US~2/07388
~9
211666~
Generally speaking, in Figure 34A each the arms a~e
configurcd similar to the form of the arms discussed above.
The arms may, if desired carry a groove, although it should be
5 understood that sueh is not required. In Figures,34B and 34E
the arms are configured from rods. Although the rod~ shown
as round in cross section it sbould be understood that they ean
have any desired alternate cross section. In Pigutes 34C and
34F the arms are con~lgured in a generally planar bar form. As
10 will be fully set forth herein, in Figure 34D tbe four arms may
be formed by sawing the upper and lower arms (indicatcd by
the char;aeters 22A, 22B in Figures I to 4) along a eut line
extending perpcndicular to the major surfaces 26 and 28 of
eaeh of tbe arms, thereby to define upper and lower pairs of
15 arm segrnents, or "fingersn. As used in this application, the
term "fmgers" is to be und¢rstood to be tbe structures defimed
wben an "armn, as that term has been used herein, is
subdivided into two a~cially dongated segments.
However eonfigured the arms are shown in Figures 34A
througb 34Fas angularly juxtaposed in a surrounding
reladonship to the cbannel 92 defined their cooperative
assoeiadon. Similar to the situation deseribed heDtofore the
resilieney of tbe arms defînes the Wasing means wbich urge
the ~ns toward the elosed position. However, it should be
understood that the biasing means may be othenvise defined,
so lo~g as the force on each arm passes througb the reference
axis and tbe sum of forces on the arms when tbey are in the
eentering position is substantially equal to zero. Whatever
fonn of biasing means is seleeted the bias force must incresse
with defleetion of the ann. The arms act against the fiber F
insened into the ehannel along the various lines of contact LC
illustrated in Figure 34 to maintain the predetennined point on
the fiber on the reference axis R.
3~
WO 93/05415 PCI'/USg2/07388
666Qo 40 '"'
- O- O- O -
In practice, during fabdcation of tbe posidoning device
misalignmcnt may sometimes occur bctwccn the first and
S sccond arm in the arm pair (Figurc 1). As a rcsul~, in use,
thc fibcr may bc supportcd by only two diameffically opposcd
sidcwalls on the fi~t and sccond arms (scc Figure 43). Thus,
thc fibcr may not be positioncd to lie along the rcfcrcncc axis.
A positioning apparatus 205 in accordancc with the
embodimcnt of the invention shown in Figures 35 through 40
is bclicvcd able to avoid this result. With refercnce to these
Figurcs it is secn tbat cach arm (225A, 225B. Figure 35) is itself
loDgitudinally slit along slit lincs 215 thcrcby to define a set of
15 four fngcrs, 22S-l. 22S-2, 225-3, 22S-4, arrangcd into a first,
upper, pair of fingcrs (225-l, 22S-2) and second, lowcr, pair of
fingcr pairs (22S-3, 225-4).
As shown in Figure 36A, in a manner gencrally similar to
20 tbc ear}icr discusscd embodiments, each finger in thc sct
includcs a basc portion 24S baving a f rst major surface 265
and a second, opposcd, major surface 28S. The basc portion
245 cxtends along thc full length of cach fingcr and thc
dimcnsion of thc contral region 25S of thc base portion 245
2S dcf~cs thc basic dimcnsion of cach fingcr.
A clip gcncrally indicated by the rcfercnce charactcr 305
is dcfined at a first end of cach finger 22S. The clip 305 is
formcd in a relatively thiclccr abutment portion 325 that lics on
30 thc first surfacc 265 of cach finger 22S. The abutment 325 has
a planar surface 345 thereon that preferably lies parallel to the
first maJor surface 265. Again, to provide some fceling for the
physical dimensions involvcd, the fingcr 22S has an overall
lcngth dimension on thc order of twenty four hundred (2400)
35 micromctcrs and a width on the ordcr of cight hundred (800)
. . .~
WO 93/054lS P~/USg2/07388
41
- 2ll6668
micrometcrs. ln the ccntral region 255 cach finger 225 has a
tbiclcncss dimcnsion on the order of one bundred (100)
micrometers.
S Each abutmcnt 325 includcs a planar sidcw~ll 335 that
cxtcnds in an inclined manncr (at an sngle of 5~.74) from the
pcrpendicular to the major surface 265 of each fingcr. The
sidcwalls 33S in the fingcrs of the first pair 225-1 and 225-2
cooperatc to dcfinc a uniform width groovc 365 while the
sidewalls 33S in the fingcrs in tbc otbcr, mating, finger pair
225-3 and 225 4 also coopcrate to define a similar unifo~m
width groove 36S.
Each fingcr has, at tbe cnd opposite tbe abutmcnt 325, an
cnlargement gcnerally indicated by tbc rcfcrencc charactcr
54S. Thc enlargcmcnt has abutmcnts 55SA and 55SB thercon.
Eacb abutmcnt S5SA is pro~idcd with a wall 625 that
coopcratcs with thc corrcsponding wall 62S on the othcr finger
in tbc pair and with a portion of thc major surfacc 265 of thc
basc portion 245 ncar the second end thcreof to fonn a
noncon~erging, uniform width, truncatcd V-shapcd trough 605.
In thc cmbodiment shown in Figurcs 35 and 36 thc trough 605
is uniform in depth along its axial lcngth, as mcasurcd with
respcct to a dimcnsion linc crccted pc~pcndicular to the
surfacc 565A cxtcnding toward thc major surfacc 265. The
trough bas an a~is 705 extending ccntrally and axially
therctbrough. The trough 605 is widcr than the width
dimcnsion of the groovc 36S. ln a morc prcferred arrangcment
the trough 605 communicatcs` with a converging lcad-in 68S
dcfincd by~the cooperadve association of surfaces 695 provided
on cach abutment SSSA on the fimgers in the pair.
A most prefcrrcd arrangcmcnt has two anglcd surfaces at
cach Icad-in corncr of cach abutmcnt, as shown in Figure 36B.
35 Abutmcnts 325 lookcd similar to thc abutmcnts 55SA beforc a
WO 93/054lS PCI~/US92/07388
42
cut is made lo fcrm tbe linear fronl edges of the abutmenls
325, as shown in Pigurc 36B. As will become clcarcr hcrein, the
surfaces 56SA on the abutments S55A of opposcd fingcr pairs
arc joincd, by any convcnient mcans of attachment, as by
S fusing or soldedng. In Figure 36B thc latetal surjfaccs of tbc
abutmcnts 325 and tbc abutmcnts SSSA are ranfpcd or inclincd
with rcspcct to thc major surfaces 265.
Tbe surface 56SB on the thc abutmcnt 555B depcnding
10 from thc surfacc 285 is spaced a prcdctcrmined distancc 805
from tbe surfacc 285 of thc fingcr 225. As will also become
clcarcr hercin, the abutmcnt 55SB thcrcby functions as a
standoff to spacc thc fingcr away from a foundation or slab on
which it is mountcd.
ln thc asscmbled condition, bcst shown in Figurcs 35 and
Figurcs 37 tbrough 40, corrcsponding fingcrs in each pair arc
disposcd in supcrimposcd rclationship onc abovc thc otbcr,
witb ~c groo~c 36S and tbe trough 605 cooperativcly dcfincd
20 by tbc fingcrs in one pair rcgistering with tbc corrcsponding
groo~e and trough formcd by thc cooperadvc acdon of the
fingcrs in the othcr pair.
Tbc groovcs 365 formcd by the coopcrative ~ction of thc
25 fingcrs in cach pair are thcmselves registercd and tbus
coopctate to define a channel 925 (Figures 35 and 39). The
channcl 925 bas an input cnd 94S and an output cnd 96S. The
rcfcrcncc axis R cxtcnds ccntrally and axially through thc
channcl 925. Prcferably, thc`refcrcnce axis R lics in a rcfcrence
30 plane RPl containing the surfaces 565A on each finger 225 ~see
Figure 38). Most prefcrably, the reference axis R also lies in a
second reference plane RP2 (Figure 39) containing the slit lines
215 dcfining cach pair of fingers in the finger set. It should be
understood that manufacturing tolerances can result in slight
35 misalignmcDt of axis R with respect to the reference plane RP2.
wo 93/05415 Pcr/us92/o7388
43 21166G8
The consequences of such a misalignment will be discussed
more fully hereafter.
The registered troughs 605 (and lead-ins 685, if present)
5 eooperate to define a guideway 985 (Figures 36B and 38~. The
axis R' through tbe guideway 985 lies in the plane eontaining
the eonjoined surfaees 565A of the abutments 55SA (see Figure
38). The plane RP2 (Figure 38) eontains the axes of the troughs.
The altes R and R' both lie in the referenee plane RPI (the plane
10 of tbe surfaees 565A) ar~d should preferably both lie in the
referenee plane RP2-
ln the embodiment shown in Figures 35 through 40 thesurfaees 345 on opposed eotresponding fingers in eaeh pair are,
15 when in a first, elosed, position, eitber in eontaet with eaeh
otlier or may, as preferred, be within a predetermined elose
distanee to eaeh otber to insute tbey will not be affeeted in
joining operadons. For optieal fibers the predetermined elose
dista~lee is typieally on the order of one (1) to two (2)
20 mierometers. The planar sutfaees 34 are not seeured to eaeh
other and thus may move to a seeond, eentering, position, as
will be deseribed.
As seen in Figure 35 the positioning appatatus 205
25 funher ineludes, in the preferred instance, a mounting slab 745
baving a planar attaehment surfaee 765 thereon. Tbe surface
S6SB of the abutment 55SB on each ftnger 225-3, 225~ is
secured, as by fusi~g or soldering, to the planar attaehment
surface 765 on tbe slab 745. Owing to the presenee of the
30 abutment 55SB, the surfaees 285 on the fingers 22S-3, 225~ of
~he lower pair are spaeed the distance 805 from the attachment
surface 765. lt should be understood that the abutment 555B
may be omitted, and the lower fingers 225-3, 225-4 may be
mounted to a foundation 74having a step 82thereon similar to
35 that shown in Figure 1, in order to provide the clearance
, , ,, ., ., . , ., ... . . , . , . ,, . , .. , . . ~ .. . ., . . . ~ . .. .
wo 93/054lS Pcr/us92/o7388
~,~666Q~ 44
di~tarlee 805 neeessary to permit -lhe movement of the lower
fingers in eaeh pair. The fingers 225-1, 225-2 in the upper pair
of fingers may also be seeured. as by fusing or soldering, to the
planar attaehment surfaee 765 on a seeond slab 745. The
5 seeond slab 74S is shown in outline in Figure 3S; _
When assembled, as shown in Pigure 35, the clips 305
disposed at the ends of the fingers 225 are supportcd in a
eandlevered fashion from the eonjoined enlargements 54S at
10 ahe opposite ends of the fingers. Eaeh of the fingers 225 is
relatively tigid in x-z plane, as defined by the eoordinate axes
sh~wn in Figure 35. Moreover, the relatively thin dimension of
the eentral region 255 of the base portion 245 of each finger 225
axially intermediate the respeetive abutments 325 and the
15 enlargements S4S aets as a flexure and permits the elips 305 at
the end of eaeh finger 225 to flex, springboar~ fashion, in the
direetions of tbe arrows 885 in the y-z plane. Again, as the
term is used herein, a flexwe is a spring member that is
reladvdy rigid in one plane and is constrained to flex in the
20 orthogonal plane.
lt should further be appreciated that when a clip 305 is
défleeted in its eorresponding respective direetion 885 the
resilieney of the thinner eentral region 255 of the base 245,
25 aeting as a flexure, defines means for biasing the fingers 225
and the elips 305 thereon toward the first, elosed, position. The
biasing foree acts on eaeh elip 305 in a direetion shown by the
arrows 905 eounter to the biasing direetions 885. It should be
understood that any other eonvenient meehanism may be used
30 to provide the means for biasing the clips 305 toward the
elosed posidon. The biasing forces must be substantially e4ual
and in opposite d*eetions. Biasing means employing the
thinner eentral region 255 of the base 245 as a flexure is,
however, again preferred beeause when implemented in a
3~ single l:rystal material using a microfabrieadon technique
WO 93/05415 PCI~/US92/07388
.,
~ 45 2116668
precise control of the biasing forccs is able to be attaincd.
Typically thc bias force on cach finger is on the order of twenty
(20) grams.
-o-0-o- `
Ha~ing dcfined the structure of thc positioning apparatus
205 in acc~rdance with this cmbodimcnt of the invcntion, the
opcration thercof in positioning a point P on thc center axis and
10 on Ihc end face E of an opdcal fiber F along a predctermined
refercnce axis R may bc rcadily understood in connection with
Figures 38 through 43. As mentioned earlier. and as is clcarly
~isiblc in Figure 41, whcn positioning thc poh2t P intG
alignmcnt with Ihc reference axis R thc positioning apparatus
15 actually contacts thc fiber at contact points Iying a closc
distancc from thc end facc E.
Assuming tbat the referencc axis R (Figure 39) of the
channd 92 aligns with both thc ff~rst and sccond rcfcrencc
20 plal~es RPl, RP2 (Figurc 38), the operation of thc positioning
dc~nce 205is substantially idcntical with the operation of the
positioning devicc shown and discusscd earlicr in connection
with Figure 6 through 8. Thus, thc fiber F is inserted into the
positioning apparatus 20S in the direction of thc arrow 1025
~2S (Figwcs 37, 41). Thc fibcr F is inse~ted into the guideway 985
- dcfincd by tbe registered troughs 605. Thc fiber F cnters the
channel 925 and is initially displaced, or moved, through
contact with at Icast one of the sidcwalls 335 or portions of the
major surfacc 265 used to define the groo~cs 365 on one of the
30 clips 305 to thc extent necessary to accurately place a
p~edct~amined point P on an end facc E of thc ffber F toward
a1ignmcnt with the rcfcrence axis R.
.
Since the outer diameter of the cladding layer L, shown
3S on Figures 41 and 42, of the fiber F cxcceds the dimension of
.
wo 93/05415 PCI/USg2/07388
Q~ 46 ~ ~i
666
the channel 765 formed by the sidewalls the fingcrs 225
respond to a deflecting force in the direcdons 885 imposed
thereon by the fiber F by displacing from the first, closed,
position (shown.~in Figure 39) toward a second, centering,
5 position shown in Figures 42 and 43. In the cen~ering position
the clips 305 open against the bias force acting i'n the directions
goS generated by the flexing of the fingcrs 225 to scparate the
surfaccs 345 thereon. This movement of the finger 225 from
the first toward the second position accurately positions the
10 point P on the end face E of the fiber F in alignment with the
reference axis R. The end face E of the fiber F thus exits
through the outlet end 965 of the channel 925 with the point P
accurately positioned in alignmen~ with the reference axis R, as
is shown in Pigures 34 and 42. The fiber F is held in this
15 position by contact with the sidewalls 33S.
-o-O-o-
As alluded to earlier, in somc instances, owing either to
20 misalignment bctwecn arms (before they are slit to form finger
pairs), misalignmcnt bctwcen the slit lines 2lS in each finger
pair and the dcsired location of the slit lines on cach arm,
mismatcbes of finger thiclcness, and/or mismatchcs of finger
widths, the asscmblcd position of the superimposcd fingcr
25 pairs will appcar as shown in Pigure 43. Diametrically opposite
sidewalls 33S on diamctrically opposite abutments 325 are not
equally spaced from the refcrence axis R. The misalignment of
the anns (prior to slitting to form finger pairs) is indicated by
the rcfercnce character Ma. `The misalignment of resulting slit
30 lines 2lS is indicated by the reference character MS.l and MS-2-
The mismatches of finger thickness is indicated by the
reference character M~. The mismatches of finger width is
indicated by the reference character Mw.
W093/05415 rCI/US92/07388
~ 211~668 - ;;
As seen in Pigure 43 whcn a fiber F is inserted into the
cba~ncl 925 formed from arms or fingcrs with such
misalignment(s), the fiber F will first strilce a first, and then the
sccond, ~3f two diamctrically opposed ramping lateral surfaces
S of the Icad-ins of the abutmcnts 325 (Pigure 36B~ before
contaclting the sidcwalls 335. These initial contact Doints on the
fingors 22S-2, 225-3 are illustratcd in Figure 44 at refcrence
characters 3351. Those sidew~lls 33S first contacted by the
f~ber F are forcedl apart in the dircctions 935A, 93SB. However,
10 since tbe bias forces generated by the movcmcnt of the first
contactcd sidewalls are opposite, the fiber F becomes centered
in an interim centered position in a plane parallel to and
centrally bctwccn such two surfaces. This interim centered
position lies at some point in the plane indicatcd in Figure 44
15 by thc line dcnoted at rcfcrcnce character Pl.
Continucd advancement of t~e fibcr P through the
channcl 925 causcs thc outcr diamcta of the fiber F to touch
onc or both of tbe rcmaining sidcwall pair. The fust touch of
20 Ibc fiber to the sidcwalls 335 jS not thc f~al position of tbe
fibcr. The final position of the fibcr is achieved when the two
fingers on the sidcwall pair 225-1, 225-4 (l;igure 44) have
moved sufficicntly to center the fiber. These final contact
points are illustrated in Figurei 44 at reference characters 335F-
25 Since the bias forccs created by movement of these last twosidewalls are also equal and oppositely directcd thc fiber is
finally centered on the intersection of the plane Pl and another
p1ane PF. The plane PF plane is parallel to and centrally located
between the two surfaces touched at the contac~ points 335F-
The final position of the fiber F may bej displaced ~romthe desired reference axis due to the misalignments defined
earlier and to other variations within manufacturing tolerances
as described bdow. To malce a positioning apparatus, or a
35 connector or an opto-electronic component utilizing the same,
WO 93/05415 P(~/US92/07388
~2~ 48 ~;
66G
for typical single mode optical fibers, the posidoning apparatus
must bc ablc to handle fibcrs ranging in diametcr from 125 to
128 micrometcrs. This range is found to be the typicat
diametcr variation in quality single mode fibcrs.
S ,~
To insure tbat a fiber is hcld propcrly by all four fingers
in thc most prcfcrrcd cmbodimcnt (Figurcs 35 to 45) the
alignmcnt,of wafcrs for bonding during the fabricadon process
to bc discusscd must limit variadon of thc misalignmcnt in thc
10 dircction across tbc groovcs (thc dimcnsion M, of Figurc 43) to
+ or - 9.5 micromctcts. This dirccdon of misalignment rcduces
tbc rangc of fibcr diamctcr variadon tbat arc handlcd in thc
most prcfcrrcd cmbodimcnt. Tbe misalignmcnt of wafcrs in
tbc othcr dirccdon, along thc Icngth of thc rcfcrcncc axis
15 sbould bc no morc tban twcnty (20) micromctcrs. This
dirccdon of misalignmcnt rcsults in tbc clamping points of one
pair of side-by-sidc ~mgcrs bcing axially displaccd from thosc
points of thc othcr pair of sidc-by-sidc ~mgcrs, which would
tend to bcnd thc fibcr sligbtly upwardly or downwardly.
Thc misalignment of thc slit or saw cut, (Ms in Figurc 43)
must be no morc than ten (10) micrometers to avoid cutdng
into a sidcwall of a groovc whcn thc slit width is sixty-six (66)
, widc; as obtained by using a typical sixty (60)
25 micromctcr saw.
Tbc thiclcness of the flexure portion of the fingcrs should
not vary by more than + or - three (3) micrometcrs so spring
forccs ~,vill be balanced with the fibcr ccntcrcd.
Commonly hcld tolcrances in the microfabrication arts,
such as in the microfabrication of dcYiccs as pressure rupture
discs, arc wcll within the above rangcs. ln fact, assuming the
usc of an cnhanced positioning apparatus having an alignmcnt
::
WO 93~05415 PCl`tUSg2/07388
49
2 1 1 6 1~
clamp, as shown in Pigure 45, estimates show, in practice, the
above maximum variations would result in
+1- 5 micrometers for sidewise misalignment, Ma,
+/- 1.5 micrometers for for fle~cure thiclcness M~,
+/- 10 mictometers for axial misali,gnme~ts~ of wafers.
Other variatdons such as flesure width aud friction encountered
when a fiber is centered by acdons of the four fingers are
small. The net result using commonly achievaUe
manufacturing tolerances for microfabricated parts is well
under one (1) micrometer in displacement of the center point
on the end face of the fiber &om alignment with the reference
axis. Even for the maximum ~ariadons discussed above, the
displacement of tbe center of the fiber end face from alignment
with tbe desired reference axis is well under one (1)
1 5 micrometer.
-o-O-o -
Witb reference to Pigures 42 and 44 (whether the ~mgers
are mismatched or not) since the fiber is supported only at
points of contact between each of the fingers in each finger
pair, the Iength of the fiber behind the eontacts is free to pivot.
To a~oid this eventuality it is desirable to enhance the ability
of tbe positioning apparatus to precise position a ffber into
alignment with a reference axis. To this end, it lies within the
contemplation of tbe present invention ~o provide a clamp,
generally indicated by the reference cbaracter 220, for
engaging the fiber a predetermined distance 224 along tbe
referenee a~is from the vicinity of the points of contact
between the fiber F and the fingers 225. Such an enhanced
positioning apparatus 205E is shown in Figure 45.
As is best seen in Figure 45, tbe enhanced positioning
apparatus 205E comprises a f*st, forward, positioning
apparatus 205 a~d a clamp 220 disposed a predetermined
.... , ... . . , . , .. . .. ; ... . , ... . " .. . . .. .. ..
WO 93/05415 PCI~/US92/07388
Q~ 50
666
- distanee 224 behind the positioning deviee 205. The clamp 220
is preferably implemented using a seeond posidoning
apparatus 205. However, any other of the positioning
apparatus 20, 201, 202. 203 or 204diselosed herein may be
5 used as the elamp 220. Moreover, the elamping funetion may
be performed by any a~rangement of suitable form.
It is, of course, understood tbat an enhaneed positioning
apparatus similar to that sbown by referenee eharaeter 205E in
10 Pigure 45 may be obtained using a forward and rearward
arrangement of positioning apparatuses. Any eombination of
positioning apparatus 20, 20', 20", 203, 204, or 205 as disclosed
herein may be used tO implement the forward positioning
apparatus and the elamp, thereby to form an enhaneed
15 positioning apparatus 20SE.
The elamp 220 serves to position aeeurately a point on
the eenter axis of the fiber into alignment with the referenee
axis. Tbis seeond point on the eenter axis of the fiber is spaced
20 a _ncd distanee from the end faee of the ~Ibcr. By
providing the elamp 220, any angular misalignment between
the flber axis and the referenee axis is held to a minimum.
-o-O-o -
2S
It should also be apparent, similar to the situa~iondiselo$ed in Figures 30 through 33, that a positioning device
205 or an enhaneed positioning apparatus 205E in accordance
with this invention ean be used with an edge aedve or a
30 surfaee aetdve opto-eleetronic device to define an opto-
eleetronic eomponent.
In sueh a usage, the slab 745 would be extended, in the
manner shown in Pigures 30 and 31, to provide a pedestal
35 similar to the pedestal 174, on whieh an edge active device 170
wo~3/os4ls 2116 6 6 3 Pcr/usn/073ss
may be mountcd. Tbe dcvice 170 may be mountcd to thc
pcdestal in the manncr earlicr discusscd. Alternadvely, the
slab may be modified to providc a pedcstal similar to that
shown in Figures 32 and 33, to accept a surfacc acdve dc~ice
5 170. As is the casc in thc earlicr, the device 170_may take the
fotm of a solid state lascr, a photodiode, or a light emitting
diode, whether thcse devices are cdge or surface acti~re. The
axis X of the de~rice is collincar with the rcference a~cis of the
posidoning apparatus 205 so ~at a fiber aligned by the
10 apparatus 205 with the rcfcrence axis will be in alignment with
the dcvice 170. The positioning apparatus 205 may be
modiftcd as suggcsted in Figure 31A, if desired, to acccpt a
Icns.
1 5 -o-0-o-
If it is dcsircd further, it should be appreciated that the
positioning apparatus 205 or an cnhanccd positioning
apparatus 205E in accotdancc with this invcndon can be used
20 to fashion a connector apparatus for holding the facial ends of
two confronting fîbcrs cach in alignment along a
predetcrmincd common reference axis.
To ~is cnd it is advantageous to mount onto the slab 745
25 a two confrontadona11y disposed positioning apparatuses 205
or two confrontationally disposed enhanced positioning
apparatuses 205E, (or a combination of the same).
The connector arrangement of positioning apparatuses
30 205 or apparatuses 205E may be disposed in a suitably adapted
housing gcne~ally similar to that shown in Figures 25 to 28, it
being understood that the reference character 120 in Figures
25 to 29 indicates a connector formed of confronting apparatus
205 or apparatuses 205E. Most preferably, the housing should
35 be fabricated material with a low thermal coefficient of
'':
WO 93/05415 PCI~/US92/07388
".,`.~,
~ 666~ 52
expansion over a temperature range &om (~5 F to + 8S F).
A suitable preferred material is a liquid erystal polymer such
as that sold by Hoeehst Celanese Corporation under the mark
"Veetran. Codvendonal molding proeesses for that polymer can
5 be used to form tbe housing. ~_
-o-O-o-
The photolithographic microfabricadon technique used to
10 manufaeture a posidoning apparatus in aeeordanee with this
invention may be understood from the following diseussion
taken in eonneetion with Figures 46 to 52. Although the
diseussion is east in terms of the manufaeture of a fiber-to-
~Iber eonneetor using the preferred embodiment of the
15 enhaneed positioning apparatus 20sE as shown in Figure 45,
the ~chings are readily extendable to the manufaeture of any
of the embodiments of the positioning apparatus heretofore
deseribed, ineluding their use in tbe various other applications
pre~iously set forth. (For elarity of deseripdve text, the basic
20 referonee eharaeters (i. e., without superseripts) of the
elements of the positioning apparatus are used.)
~ A silieon wafer 200 having an appropriate predetermined
erystallographic orientation is the starting point for fabrieation
25 of ~c arms 22 of a positioning apparatus 20 in aceordance with
the present invention. It should be understood that other
single erystalline substrate materials, sueh as germanium, may
be used provided appropriate alternative etehants and
materials eompatible with the seleeted alternative substrate
30 are used. The wafer 200 is polished on at Ieast one surface.
Suitabh sUieon wafers are available from SEH America, Inc., a
subsidiaq of Shin-Etsu Handotai Co. Ltd., Tokyo, Japan, located
at~ Sparta, New Jersey. It should be understood that the wafer
200 ean be of the "p-type", "n-type" or intrinsic silieon.
wo 93/05415 Pcr/uss2/073ss
53
2116668
The substrate mateAal is preferably (100) surface silieon
beeause this material ean be etehed by anisotropic etehants
wbieh readily act upon tbe (100) erystallograpbie plane but
substantially do not eteh the (111) plane. As a result the
5 preferred truneated V-sbaped grooves 36A, 36B,, the t~oughs
60A, 60B, the lead-ins 68A, 68B and tbe eentraI' region 25A,
25B of the arms 22A, 22B between the abutments 32A, 32B
and the enlargements 54A, 54B are easily formed. Tbe width
and depth of sueh features are dependent upon the preseleeted
lO width of the opening in the pbotolithographic mask being used
and tbe time during whieh the etchants are permitted to act.
Etehants operate on 100 surface silicon in an essentially self- -
limidng manner which property is useful in forming a full
V-groove. One of skill in the an will reeognize that if other
15 etoss-seedon eonfigurations are required, other predetermined
erystallographie orientations of the silieon may be used. For
e~cample, if square eross-seetion features are desired, (110)
surfaees silieon wafas ean be used. Other eross seedonal
esnfiguradons for the features are, however, signifieantly more
20 e~cpensive and, as will be seen later, would require a more
eomplieated eonfiguration to obtain the ~lber eentering aedon
equivalent to that inherent in a V-groove.
Figure 46 Is a plan view of the wafer 200. The wafer 200
25 has pcripheral fl~ts 201 and 202, as speeified by the SEMI -
Standard. Tbe flats 201, 202 p~imarily indieate orientation of
tbe erystallographie strueture of the silieon and are also uscd
for wafer identifileadon and mask alignment. The longer flat
201 indieates the dircction of erystallographic plane (110).
30 The shorter flat 202 is plaeed a predetermined angular amount
on the periphery of the wafer with respeet to the flat 201, ~he
magnitude of tbe angle depending upon the doping of the
erystal.
WO 93/05415 PCI~/USg2/07388
54 ".
,666~
As will be dcveloped, the pcripheral rcgions 203 of the
wafer 200, when prepared, carry alignmcnt featurcs, while the
central region 204 of the wafer 200 has the structural fcatures
of the ann or foundation, as the case may be, of the posidoning
5 appalatus formed thereon.
Figure 47 shows a mas~ 210 with a pattcrns 212 of
alignment featurcs, such as orthogonal alignment grooves or
alignment through holes 212H and corrcsponding wells 212W,
10 thercon. The holcs 212H arc etched from the oppositc surface
of thc wafer as are the wells.
If grooves are used, the grooves in each pattcrn 212 are
graduated in size to accommodate various sized (diameter)
15 quartz alignment fibers. The grooves 212 have a V-~haped
cross section to acccpt fibcrs ranging ir~ width from about
0.004825 incbcs (0.123 mm) to 0.005000 inches (0.127 mm) in
0.039370 inch (0.1 mm) steps, ffve groo~rcs 212 having been
illust~ated. Thc groove width (at thc open top of the groove) is
20 largcr than the diameter of the fibcr so that the center of the
fiber is substantially coplanar with the surface of thc wafcr
when thc fibcr is disposed in its associatcd groove.
Accordi~gly, for a 0.123 mm fibcr, a groove 0.1506 mm is
providcd. Similarly, for a 0.124 mm fiber, the open top
25 dimension of tbe groove is 0.1518 mm. ~or a 0.125 mm ~Iber,
the open top dimension of the groove is 0.1531 mm; for a 0.126
mm ~lbcr the open top dimonsion of the groove is 0.1543 mm.;
and for a 0.127 mm ~lber, the open top dimension of the groove
is 0.1555 mm.
A central area 214 of the mask 210 has provided thereon
a repctitive pattern 220 (one of which is shown in Figure 48)
containing to a predetermined number of structural features
(i.e., arms or foundations mor slabs) of the positioning
35 apparatus 20 bcing formed. Since the typical wafer 200 is
WO 93/05415 PCI/US92/07388
S5
- 2116668
about 3.9381 inches (101.028 mm) in diameter and a typical
conncctor 120 measures about tbree hundred fifty (350)
micrometcrs at the widest location and is about two thousand
dght hundred (2800) micrometers in Icngth, the structural
5 f~a~,ures for approximately one thousand (1000,~ connectors
12~ may be forrncd from thc ccntral region 20~ of the wafer
200.
Figure 48 is an enlarged vicw of a portion 220 of the
10 pattern provided on the ccntral region 214 of the mask 210.
In Figure 48, the pattern illustrated is that used to form a
plurality of conjoincd anns 22 used in a connector 120. The
pattcrn 220 is formed on the surface of the central region 214
of the mask 210 using a well-lcnown step and repeat proccss to
15 covcr the entire area.
Tbc rcpctitivc pattcrn 220 shown in Figure 48 is
compriscd of a plurality of columns 224 which are def~incd
bctween an array of adjaccnt parallel scribe lincs 226 and a
20 ~lrst and a second scparadon linc 227A and 227B. Each column
224 contains tcn (10) discrcte zones 228A through 228E that
are symmetrical within the column 224 about a cutting line
230.
Seen bctween two next adjacent scribe lines 226 is the
conf1guration of two arms 22 joincd front end to front cnd.
Scen bctween thrce next adjaccnt scribe lines 226 is the
configuration of two anns 22 joined lengthwise side to side.
The zonc 228A corresponds to fcatures defining the region of
Ithe Icad-in 68A of an arm 22A. The zone 2:28B corresponds to
featur~s defining the region of the trough 60A of the arm 22A.
Similarly, zone 228C corresponds to the central portion 25A of
the arrn 22A, while the zone 228D corresponds to features
dcfining the region of the converging groove 36A on the arm
35 22A. The axis 50A of the converging groove 36A is offset from
wo 93/05415 rcr/us92/07388
56
?~ the axis 70A of tbe trough 60A by the offset distance 100.
Pinally, if provided. the zone 228E corresponds to fcatures
de~lning the region of the tabs 48A of an arm 22A. Note that in
the mask illustrated in Figure 36 the position of the offset 100
5 on one side of the cutdng line 230 is reversed fro~n the position
of thc offsct 100 on the opposite side of thc cutdng line,
although this arrangement is not nccessariiy requircd.
Tbe repedtive pauern for a mask of the arm 22B will be
10 similar to that shown in Figure 48 except that the direction of
the offset distanccs 100 for the arm 22B will be the mirror
imagc of the pattern for the arm 22A. As will become clearer
herein, this mirror image relationship between the offsets is
neccssary so that so that features on the resulting anns 22A,
15 22B will registcr with each other when one is inverted and
superimposcd on the othcr. Of course if the offset 100 is
eliminatcd, masks for the arms 22A and 22B will be identical.
Tbe cross-hatched areas shown in Pigure 48 preferably
20 corrcspond to those areas of the central region of the wafer
200 that will be protected by a layer of resist material (as will
be dcscnbed) while the areas shown without hatching will be
Icft unprotected during subsequent etching steps. A ncgative
rcsist is cmployed but it should be apparent that the lo ation of
2~ the hatched and clcar arcas of Figure 48 may be revcrscd if
desircd. This would alter somewhat subsequent steps, but in a
manncr known to those in the art.
Pigures 49A through 49E iilustrate the process steps
30 whcrcby a wafer 20Q of crystalline silicon may be formed into
an array of arms 22A corresponding tO the array shown on the
mask of Pigures 47 and 4~. As seen in Figure 49A the wafer
200 is preliminanly covered with a layer 232 of a material that
acts in a manner similar to a mas~;. Silicon dioxide (sio2) is
35 prcfcrred, and is surfaced onto the polished operative surface
Wo 93/05415 ~ uss2/073ss
57 2116668
.
200S of the silicon wafer 200 by thermally growing the silicon
o~cidc layer in an oxygen atmosphcrc at devated temperature
(circa eleven hundrcd fifty (1150) dcgrees Celsius), as is
Icnown. As indicated, silicon oxidc is used becauæ a~.railablc
5 ctchants that attack silicon will also attack Icno~n photorcsists
but will at~ack thc oxidc only slightly. This sli~t attack is
accounted for when dimcnsioning the photomasl~.
-
The layer of silicon oxide 232 is then co~rered with a
10 photoresist 234. Preferred is a positivc resist, such as themixturc of 2-ethoxyethyl acetate, N-butyl acetate and xylene
sold by Shipley Company, lncorporated of Ncwton,
Massachusetts, as "Microposit Photoresist" 1400-37. The resist
is spun onto the surface of the silica dioxide in accordance with
15 ins~rucdons set forth in the Shipley Microelectronic Products
Brochure (1984) using standard apparatus such as that
avdlable from Heàdway Rescarch Incorporated of Garland,
Te~tas under modcl number ECR485.
The mask 210 is mountcd atop the wafer 200 and is
aligncd with respect to the flats 201, 202 of thc wafcr 200
using alignment bars 23~. Thus, in a fimished wafer the
alignment grooves 212 are preciscly positioned with respect to
thc flats on the wafcr through the use of alignmcnt bars 213 on
the madc. The wafer 200 is cxposed to ultra~riolet light
through the mask 210 and subsequently developed.
Since a positive resist is used the unexposcd areas of the
rcsist are washcd away using dc-ionized water, leaving the
SO ! layercd arrangement of cxposed, hardened resist 234, silicon
dioxide 232 and wafer 200, as shown in Pigure 49B.
Next the pattern of the mask 210 is etched into the silica
layer 232. Buffer hydrofluoric acid (HF) is preferred. This step
35 results in the a~rangement slbown in Figure 37C. Those slcilled
wo 93/05415 Pcr/uss2/o7388i
5 8
6 in the art will recognize that process variables such as, for
- example, concentration, dme and temperature are all adjusted
appropriately to opdmize results in all of the wet proccssing -
stcps describcd.
Tbercaftcr, a second, differential, ctcbing s'tep is
pcrformcd to etch the silicon to form the fcatures of the arms
22A. Tbe prcfcrrcd anisotropic etchant is tcn perccnt (10%)
potassium hydrcxide (KOH). Ethylcne diamine ("ED")
10 pyrocatcchol ~nP") and watcr, in a mix of 750 ml ED, 120 gm P
and 240 ml watcr, may be uscd. This ctching produccs thc
structural fcature in the surface of the silicon illustratcd
schcmadcally in Figure 49D by refcrence character 236. The
dcpth of the feature 236 is controlled by controlling the ctching
15 dmc, as is wcll Icnown. Of course, diffcrcndal etching is sclf-
limiting for the insidc anglcs of thc structure, if left to procced.
The silicon dioxide laycr 232is thcn rcmo~cd by ctching
with buffcr hydrofluoric acid (HF) and anothcr laya of silica,
20 i.c., silicon dioxidc, is grown on thc surface. Ncxt, rcsist is
dcpositcd on thc surfacc of thc wafcr and is imaged through a
maslc, as shown Figu;re 38. This results in a layer 238 of
bardcned resist bcing formed on those prcdetennincd portions
of the wafer thiat are to bc bondcd (corresponding ~to zoncs
25 228C through 228E and to troughs 60 (see Figure 36)).
The silica layer is then ctched ~rom arcas that are to be
bonded (See, Figure ~9E) using hydro~luoric acid (HF). The
resist layer 238 is stripped using acetone, leaving a finishcd
30 wafcr rcadyi for bonding.
This completes the fabrication of the first wafer 200
having the array of arms 22A thereon.
-o-O-o-
:::
.,
WQ 93/05415 PCI/US92/07388
59
2I16668
As notcd earlier, si~ce tbe axis of the guideway 98A may
be offset rom the axis of the groove 92A, the mask for the
arms 22B may not be identical with the mask used to form the
5 arms 22A. Accordingly, a sccond wafer having an array of
arms 22B thcreon may be preparcd in accordan'ce with the
mcthod steps illustrated in Flgure 49. Tbe finishcd sccond
wafer (not specifically illustrated but hereinafter referred to
by character 200') is similar in all respccts cxcept in location of
lO the offset 100. f thc wafcrs are the samc, the second wafcr is
prcparcd cxactly as the first.
A third wafer 200" is prepared using a foundation mlask,
a portion of which is shown in Figure 51. Pigllre 51 is an
15 cnlarged view of a portion of the pattcrn 220' providod on the
ccntral rcgion of the foundadon maslc (analagous to the pattern
of thc arm mask shown in Figute 36). The repe.titive pattern
220' is comprised of a plurality of columns 244 which are
dcfincd bctwecn an array of adjaccnt parallel scribe lines 246
20 and a first and a second separation linc 248A and 248B. Each
column 244 contains four (4) discrcte zoncs 250 that are
symmctrical within the column 244 about a center line 252.
The zoncs 250A dcfine mounting surface 76 on a foundation
74. Thc zoncs 250B correspond to the surfaces 82 providod on
25 the foundation. The wafer 200" containing the foundations 74
is exposed in a manner analogous to that shown in Figure 37,
with the cxccption that the exccption that the solder mask
exposure is not carried out. Howcver, the layer of silica is
removcd from the surface of the wafer 200n.
3 ~)
Having prepared wafers for the arms 22A (the wafer
200), the arms 22B (the wafer 200') and the foundations 74
(the wafer 200"), the final assembly of the connector 120 may
be made as is shown in Pigure 40.
WO 93/05415 PCl'~US92/07388
Q~ 60 '^`
~666
Tbe wafer 200' is placed on top of the wafer 20.
Prcferred methods of aligning wafers to be joincd involve
etcbing holes that go through one wafer and wells (shallow
bolcs) on the mating wafer accurately located by the precision
5 photomasks used for ctching so that wafers are aligned by
matching through hole with well at at Icast two l'ocations on
each wafer. One mcthod involves etcbing truncated pyramidal
through-holes and wells so that when one wafer is turned over
and placed against the sccond wafer, each bole and well can be
10 matched by obscrvation with a microscope as the wafers are
posidoncd with precision adjustmcnt mcchanisms as are well
Icnown in the micromachining art. A bctter method is to etch
V-grooves forming crosses as holes and wells and matching by
infrarcd source and camera scarching for the brightcst image
15 madc by a bcam passing through both wafers. Such infrarcd
cquipment is commcrcially available, (as, for cxample, &om
Rcsear~h Dcviccs Division of Amcrican Optical Corporation) a
most prcfcrrcd method is to ctch a grid pattcrn of lincs spaci:-g
from each othcr on tbe ordcr of ten (10) micromet*s
20 scparadon. ~n infrarcd bcam image can be inspectcd for the
brigbtcst and most uniform lincs in the imagc wherc etched
linc are aligncd Ictting the most infrarcd beam through the
two silicon wafcrs. (This latter method is bclicvcd to bc
accurate to 0.5 micromctcr, as comparcd to the method with
25 crosscs whicb is accurate to, typica11y, ten (10) micromcters .
As yet anothcr alternative, the registration of the
fcatures on the wafcr 200' to those on the wafer 200 is
cffoctcd using at least two and preferably four lengths of a
30 stripped optical fiber and the corresponding appropriate one of
thc aligDmcnt groovcs in cach array 212 of grooves. The
diamcter of each length of the optical fiber is measured by
micromctcr, accurate to plus or minus 0.5 micrometers. Each of
thc fibas is placcd in groove in the groove array 212 that most
35 closely corrcsponds to the measurcd diameter. Each alignment
WO 93/05415 PCI~/US92/07388
61
- 21I6~68
fibcr thus sits in the selected alignmcnt groove such that the
axis of the alignment fibcr lics in thc plane of the surface of tbe
wafcr 200 with the remaining portion of each fibcr protrudes
abovc that surfacc.
Tbe wafer 200' is invcrtcd ~nd placcd atop thc wafer
200, with the corrcsponding grooves in thc wafer 20~'
rcceiving the protruding portions of the alignmcnt fibcrs
thereby to precisdy align the pattern of the two wafcrs. Since
10 thc alignment grooves on cach wafcr are formcd
simultancously with the formation of the fcaturcs on the wafer,
and since the mask for cach wafer is formed opdcally one from
the othcr, precise alignment bctween the wafers is achieved. lt
is notcd in Figurcs 40A and 40B only onc of the fibers 254 and
15 groovcs 121 is shown, for clarity of illustration.
In a lcss prcfer~cd mcthod, thc asscmbly of
superimposcd wafers 200, 200'~ shown in Figurc 52 is bondcd
in a wct controlled atmospbcrc futnacc accotding to mcthods
20 dcscnbcd in tbe papcr by Shimbo et al., "Silicon-to-silicon
ditcct bonding method" publishcd 10/86 in the Journal of
Applied Physics, and in the papcr by Laslcy ct al., "Silicon on
lnsulator (SOI) By Bonding and Etcbb~clcn, IEDM 85. As sccn in
Figurc S2B tbc cxtcrior surfacc 256' of thc wafcr 200' is lappcd
25 to rcducc its thichlcss from it original tbickncss (typically
approximatcly scventecn (17) mils) to a final tbiclcness of five
(5) mils.
The more prcferrcd method of bonding uscs tbe above
30 but avoids expensivc lapping by ctching parts of thc arms and
~mgers as dcscribed bclow. and avoids forming an abutment on
the slab.
Thc rcsulting bondcd structure is invcrted and the
35 cx~èrior surface 256' of thc wafcr 200' is mountcd atop tbe
WO g3/0541S PCI~/US92/07388
62 ~""
wafer 200". The alignmcnt of thcse wafers is cffected using a
fixture cmploying quartz bloclcs 260 abutdng against the flats
201, 202 of the wafcr 200. Thc wafer 200' is then bonded to
the wafer 200n. It is to be understood that otber bonding
5 tcchniques, sucb as thosc discusscd in the papcr by Wallis and
Pomcrantz "Ficld Assistcd Glass-Mctal Scaling" puUisbed 9/69
in thc Journal of Applicd Physics may be used to bond tbe
wafcrs. Stdll other altcrnate bonding tcchniqucs would includc
mctallic or glass soldcr bonding.
Tbe cxtcrior surface 256 of the wafcr 200 is then lapped
until thc dimcnsion of tbe wafer 200 is that of the wafer 200'.
Thus, the substandal equality of the biasing forces imposed by
tbc ncxure is providcd.
The rcsultant tbrec wafer bonded stack shown in Figure
S2D may hcn bc cut. Only thc top two wafas 200, 200' of the
bondcd stack (containing tbe arms 22-lB, 22-2B and the arms
22-lA, 22-2A, rcspecdvcly, Pigurc 22) are first cut along the
20 lincs in thc wafcrs corrcsponding to the cutting lincs 230, 230'
on thc arm maslcs (Pigure 36). This cut is made using a Uade
tbat is on the ordcr of 0.003 inches to crcate the distance 122
in Pigure 22. The bondcd stack is thcrcaftcr cut, using a blade
tbat is 0.015 incbcs tbick, along tbc lincs in the wafcrs
25 corrc~ponding to thc scparation lines 227A, 227B on the wafer
200, tbc scparation lincs 227A', 227B' on the wafer 200', and
tbe scparatio~ lines 248A, 248B on the wafer 200n, as well
along tbe scribe lines 226, 226' and 246 (on the respective
wafers 200, 200' and 200") ali of which are rcgiste~ed with
30 cach otber, thcreby to yield from the bondcd stack about one
tbousand of the ~Iber-to-fiber connectors 120.
-o-O-o -
WO !~3/0541~ PCI~/US92/073~8
6 3 2 ¦ 1 6 ~ 6 8
As noted earlier, the positioning apparatus 205 shown in
Figures 35 through 44 or an cnhanced positioning apparatus
20SE shown in Figure 45 (and any connector or opto-electronic
made using the same) is fabricated in a manner generally
5 similar to th~t previously discussed in the case of the
positioning apparatus 20. Some specific points G~ be notcd.
A portion of the top surface of a wafer defines the
surface 565B of a fingcr pair whcn fabricadon is complctcd. An
10 adjoining portion of ~be wafcr is ctched to fonn tbe surface 285
of cach finger pair.
On tbe opposite side of the wafer, a portion of that
s0facc becomcs surface 56sA of cach abutmcnt 545, whilc
15 anotber portion of that wafcr surface is etched to form surface
34S of tbe abutmcnt 325 of cach clip 305. An adjoining portion
of tbat surface of thc wafcr between thc surfaces 565A and 34S
is ctchcd slightly to form the major portion of the surface 265
defining the flcxurc. The abutmcnts S4S, 325 are also ctched to
20 form sidcwall surfaces 625, 335 respectively. Each sidewall
surface 625, 335 dcfines an angle of 54.74 degrees from the
plane of the wafer due to the silicon crystal structure.
It is notcd that the ctching process usod docs not malce
25 sharp corners ~t the ends of a groove. What would have been a
corner is etchcd inward on each dde thercof. Due to ~e crystal
structure of the silicon two anglcd faces are formed at a corner
location as shown in Figure 36B. The right angle corners shown
in the Figure are formed by s`awing or cutting. The bevclcd
30 comers formed are advantageous since they serve as guides to
bdng a cylindrical object, as the fiber, into the channels 905
and 925 formed by the troughs 605 and the grooves 365,
respectively.
WO 93/0541~; PCl'~USg2/07388
,. . ~
64
66 Several finger pairs are ctched in a single silicon wafer.
All etching is done before the other fabrication stcps.
A wafer containing containing a prede~ermined numbcr
of unscparated of fingcrs is positioned on top of another wafer
containing a corrcsponding predetcrmincd numbc'r of
unscparated of fingcrs. The wafers arc aligncd so that the
surfaces 565A (see Figures 36A) of the unseparatcd fimgers on
cacil wafer surface are touching in contact. The slight ctching
of cach wafcr ~elievcs the surfaces 345 on cach unseparated
finger to prevcnt their touching and being joined.
The two wafers containing the unseparated fingcrs are
placed on a third wafer which contains a number of
~nscparated slabs 74S.
Tbe wafers arc joincd, only at surfaccs 565A, by hcating,
to fusion temperature in an oven. Known methods of joinder
such as soldcring can also be uscd.
After the joining steps are complctcd the silicon wafers
are sliced or cut, (i) down the centcrs of the grooves 905, 925
(through the abutments 3~5 and optionally, but preferably
through tbe abutmcnts 545) lo separate cooperating sets o~
fingers, (ii) to separate sets of four fingers which will beeome
positioning appa~atus, and (iii), to cut the bottom wafer. The
bottom wafer may ~e separated to define a moundng slab for a
set of four ~ingers to serve as a positioning apparatus (as in
Figurc 35), to contsin a both a forward and a rearward sct of
3G ~ur fingcrs to define as a positioning apparatus with a
rearward clamp (as in Figure 45), or to contain two
confrontationaly disposed positioning apparatus, (each of which
may include a single positioning apparatus, or a positioning
apparatus having the fo~vard and reanvard finger set.
WO 93/05415 ~ : PCI`/US92/0?3&8
21I6668
o O-o-
Those slcilled in the art, ha~ing the bencfits of tbetcacbi~gs of the prescnt in~vcntion as hcrcinsbo~c sct forth,
5 may impart numcrous modifications thcrcto. It, should be
undcrstood thu such modificadons as bcrdn 'prcscntcd and
any othcrs are to be construcd as Iyi~g within thc
contcmpladon of tbc prescnt invcndon, as defined by the
appcndcd claims.
WHAT IS CLA~D IS:
