Note: Descriptions are shown in the official language in which they were submitted.
~)9~4~6
~3 WO 92/0~460 ~ PCr/VS91/0674
OPTICAL FIBER SWITCH
~GRO~ID OF ~HE INVENTION
Field of the Invention This invention relates to a
switch for switching an optical fiber from a first to a
secand groove in response to a switching force and, in
10 particular, to a switch in which the switching force is
imposed directly on the fiber.
~ iptjon, ~,f the Prior Art Fiber optic
communication systems now use either single mode or
15 multimode optical fiber cables to transmit information
within a local area network. Switches permit optical
paths within the network to be changed to allow for the
information to be directed to a particolar unit or units or
even to bypass a particular unit. Switches for such uses
20 must exhibit a high degree of reliability over many switch
cycles, low insertion loss, low crosstalk, and short
switch times,
Several forms of optical fiber switches are known.
2 5 In some switch arrangements the switching function is
accomplished by placing an optical device within the
optical path. Copending application Serial Number
07/462t 47, (ED-0385), filed December 18, 1989 and
assigned to the assignee of the present invention, ,
30 discloses the use of a movable blocking element to switch
light from one fiber to another or to an off positi,on.
United States Patent 4,790,621 (Calaby et al.) shows the
use of a movable prism to switch light from one fiber to
another. United States Patent 4,261,638 (Wagner)
SUB5T1~ E SHE:ET
' - ' ' ' '' - - " ' .' . . ' : ' .
,' , . . . . .
- , ' ~ . :
2091 4~6
wo 92/oj460 2 PC~IJS91/06749
discloses the use of a reflecting member to switch light
along different optical paths.
- Mechanical switching arrangements are also known.
5 In such devices the optical fiber is fixedly mounted to a
movable member and the member is physically displac~d
from a first to a second position to switch the optical
path. United States Patent 4,911,520 (Lee), also assigned
to the assignee of the present invention, utilizes a ;
10 cantilevered glass tongue to which a fiber is edgewise
mounted. A first and a second fiber are similarly mounted
along edges of a fixed block. Moving the glass member
from a first to a second position removes the fiber
thereon from a first optical path that includes the first
fixed fiber and places the fiber into a second optical path ~ `~
that includes the other fixed fiber. ~
:,..:.
In United States Patent 4,407,562 (Young) optical
fibers are secured in grooves disposed on the exterior
20 surface of a movable housing. Displacement of the housing
brings the faces of the fibers into and out of alignment
with other arrays of fibers thereby to cause the s~vitchin~
action. Alignment of the movable housing with the casing
in which it is disposed is effected using alignment
25 grooves. United States Patent 4,896,937 ~Kraetsch et al.)
provides two V-grooves, one in the cover and another in
the base of a housing. The switching action is
accomplished by moving a ferromagnetic strip to which a
fiber is attached into position in one of the V-grooves.
United States Patent 4,759,597 (Lemonde) rnounts an
optical fiber to a magnetic rocker arm. The pivotal motion
of the rocker arm moves the fiber between correspondin~ '
fibers secured in grooves respectively provided in an
35 upper and a lower support slab.
5UBSTlTUrF SHE~T
- - . . -- ~ . - . . . . -. .
19~ ~6~
æ~ wo 92/0:~460 PCr/lJS91/0674
In the above discussed mechanical switches the
switching action is accomplished by moving, in addition to
the mass of an actuating element, a member to which the
fiber is attached. That member is relatively large and
massive as compared to the size and weight of the optical
fiber. These devices would thus appear to be iimited in
- their switching speed.
United States Patent 4,946,236 (Dautartas et al.)
discloses a switch in which the displacing force is applied
to the fiber itself. The switch includes fibers that are
surrounded by a magnetic sleeve. The fibers are disposed
within grooves defined by the corners of an elongated,
- 15 diamond shaped, internal channel extending through a
block. A magnetic field is applied to effect the
displacement of the fibers from one corner of the groove
to another.
In view of the foregoing it is believed advantageous
to provide an optical,fiber switch having a repeatabiy low
insertion loss, a relatively short switching time in which
the switching action is accomplished by moving (in
addition to the mass of the actuating element) only the
2 5 relatively minimal mass of the fiber.
SUMMARY OF THE INVENTION
The present invention relates to an optical fiber
switch comprising a base having a block portion thereon.
The block has a surface in which at least a first and a
second groove are formed. An optical fiber has a first
predetermined portion of its length adjacent to its end
face received in one of the grooves. The axis of the fiber
3 5 in this first predetermined portion thereof defines a
SU~3STITIJTE SHl~T
.
. . .
'~3'~1466
WO 92/0~460 4 PCT/US91/0674'J
predetermined positive an~le with respect to the axis of
the groove. The fiber is biased by a biasing force acting
on the optical fiber in a direction which urges the first
predetermined portion of the fiber toward the bottom of
5 the groove. A second predetermined portion of the fiber
spaced behind the first portion is mounted over an inclined
ramp, thereby bending the portion of the fiber forwardly
thereof. The biasing force is generated by the bending of
the fiber. Preferably the surface of the ramp defines an
1 û angle with respect to the base that lies in a range from
five (5) to fifteen (15) degrees. The ramp may be grooved, ~ -
if dasired.
:,
A switching member is reciprocally movable with
1~ respect to tha base from a first to a second position. The
motion of the switching membar is generally transverse
to the direction of the biasing force. During its movernent
the switching member engages operatively against the
fiber thereby to move the first predetermined portion
20 thereof against the biasing force out of the one groove and
into the other groove. As the fiber is displaced the
biasing force acts thereupon to urge the first
predetermined portion of the fiber toward the bottom of
that other groove. In the pref0rred instance the switching
25 member takes the form of a yoke connected via a rocker
arrangement to an actuating solenoid. The yok~ engages
operatively against an intermediate portion of the fiber
disposed between the ramp and grooved block.
A switch embodying the teachings of the present
invention may be used in any one of several switchin~
environments, such as a one-by-two switch, a two-by-two
switch, or a crossover switch.
3 5 BRIEF DESCRIPTION OF THE ~RAW~NG$
SUBSTITUTE SHEET
.
.. ~ , ~ ~ . . . .
. . . . . . . . ...
.. . , ~ , . .. . . .
u .~
WC~ 92/~ 460 PCr/l,'S91/Ofi749
The invention may be more fully understood from the
followin~ detailed description thereof, taken in
connection with the accompanying drawings, which form a
part of this application, and in which:
Figure 1A is a stylized p~rspective view of the
elements of an optical fiber switch in accordance with the
present invention from which the principles of operation
thereof may be understood, the switching member baing
illustrated in a first position and the fiber being `
illustrated as resident in a first groove;
Figure 1B is a view similar to Figure 1A with the
switching member being illustrated in a second position
and the fiber being illustrated as resident in a second
groove; :
Figure 1C is a plan view of the switch shown in
20 Figures 1A and 1B, with the fiber being removed therefrom
for clarity of illustration;
Figure lD is a side elevation view of the switch
shown in Figure 1A with a portion thereof broken away,
25 while Figure 1E is an enlarged view of a portion Figure 1D;
Figure 1F is an elevation view taken along lines 1F-
1 F in Figure 1 A;
Figure 2A is a view generally similar to Figure 1A of
- a portion of the switch there shown illustrating the
extension of the principles of the switch in accordance
with the present invention to an environment for
switching multiple optical fibers, the switch being shown
with the switching member in a first position and the
SUBSTITIJT SH~ET
-,
' ' ' ~
~)9 1 ~6
WO 92/0~460 , 6 PCI/US91/0674
movable fibers shown as each occupying a first groove,
while Figure 2E~ is a view similar to Figure 2A with the
switching member in a second position and the movable
fibers each being switched into a second groove; -
Figures 3A and 3B are views r~spectively similar to
Figures 2A and 2B that illustrate the further extension of
the principles of the switch in accordancs with the
prssent invention to a crossover switch arrangement for
10 switching multiple optical fibers;
Figures 4A through 4C are diagrammatic views that
illustrate the minimum spacin~ required between the arms
of the yok~ of the switching member for a hNo fiber
1~ switch as illustrated in Figure 2; and
Figures 5A through 5C are, respectively, a
perspective, plan and side sectional views of the
structure of a practical implementation of a switch in
2 0 accordance with this invention
DETAILED DESCRIPTION OF THE INVENTION
Throughout the following detailed description,
25 similar reference numerals refer to similar elements in
all Figures of the drawings. -
. .
The various subparts of Fi~ure 1 (viz., Figures 1A
through 1 F) are highly stylized diagrammatic views of the
30 basic elements of a switch 10 in accordance with the
present invention. Although more detailed drawings of the
structure of the switch 10 are presented hereinafter, the
various views comprising Figure 1 are useful in clearly
indicating the basic structure and operation of the switch
35 10.
SUBSTITUTE SHEET
, ~ . . . . , ., ~ . . . .. , . . :
"~ 2~31~6~
~VO 92/0~460 7 PCl/US91/0674'~
The switch 10 is operative to switch at least one
optical fiber 12 from a first position to at least a second
position. In one and/or both positions, the fiber 12 may be
5 arran~ed to optically communicate with a fixed optical
fiber F1 or F2, as will be developed.
The movable fiber 12 may be either a singie or a
multimode optical fiber and is ~ypically fabricated of
10 fused siJica or plastic. The fiber 12 has a predetermined
diameter D. The fiber 12 is illustrated in Figures 1A, 1B,
~ D, 1 E and 1 F with the jacket thereof removsd.
Accordingly the diameter D represents the diameter of the
fiber core plus its surrounding claddin~. This diameter D,
15 for a single mods fiber, is typically on the order of one
hundred hventy five ~125) micrometers.
The switch 10 includes a base 14 and a
corresponding cover 16. The cover 16, illustrated only
20 schematically in Figure 1D is arranged in any convenient
fashion for conjointure with the base 14. When joined to
the base 14 the cover serves to enclose and thereby
protect the elements of the switch 10.
The base 14 includes a block portion 18 located at a
forward portion thereof. The ~lock 18 may be mounted on
and secured to the base 14, or may be formed integrally
therewith, as shown. The block 18 has a top surface 18T,
a front surface 18F, and a rear surface 18R. The a~tial
length of the block 18 is indicated by the reference
character 18L (Figure 1D).
The top surface 18T has at least a respective first
and a second open groove 20, 22, respectively, formed
th~rein. The grooves 20, 22 interrupt at least the rcar
TIJ~; S~E
. . . ~.
, . .. -
. . ; ,
. .
..
;~ ~ 9 ~
WO 92~0~460 8 PCr/US91/0674
surface 18R of the block 18 and extend axially along the
block 18 for some predetermined axial distance. In most
instances the grooves 20, 22 extend across the entire
axial length 18L of the block 18 and thus also interrupt
the front surface 18F thereof. A planar median 18M may
be defined between the adjacent ~rooves 20, 22, if
desired.
In the preferred instance the grooves 20, 22 are each
generally V-shaped, with the sidewalls 20W1, 20W2 and
22W1, 22W2, as the case may be, of each ~roove tapering
toward a pointed bottom 20B, 22B, respectively. The
grooves 20, 22 each have an a~is 20A, 22A, respectiveiy,
extending therethrough. The respective axis 20A, 22A of
each groove 20, 22 is collinear with the bottom thereof.
As is apparent from the Fi~ures one sidewall of the
groove adjacent each lateral extremity of the switch 10
extends a greater distance above the sidewalls of the
grooves defined intermediate therebetween. Thus, in the
context of the embodiment of Figure 1 the sidewall 20W1 -
and the sidewall 22W2 extend above the intermediate
sidewalls 20W2 and 22W1.
As will become more apparent herein, in accordance
with the present invention, the precise location of the
fiber 12 when the same is in each respective groove
thereof is accomplished by the interac~ion of the fiber
with the groove. With a V-shaped groove at least two
point contact must be definsd betwcon the sidewalls of
the grooves and the fiber for precise alignment of the
fiber.
The bottoms 20B, 22B of the grooves 20, 22 each
extend at least a predetermined depth into the block 18.
SUBSTITUTE SHEET
.. . . ~ - . . .- , ~ .
. . ... . . - : . ., . .. :
9 ~
W~ 92/~460 9 PCl/lJS9~/067
Generally speaking, the grooves 20, 22 must extend to a
depth so that the fiber is precisely aligned as a result of
at least two point contact with the sidewalls of the
grooves. Thus, in practice, for a multiple movable fiber
switch using ninety degree V-~rooves, the grooves should
extend into the block for a distance approximately equal
to the radius of the fiber 12. In the case of a single
movable fiber, as illustrated in Figure 1, the depth 30
(Figure 1F) may be on the order of the fiber diameter D.
10 Although it is not required, in practice, the depth
dimension should be the same for all the grooves.
In ths preferred case, best seen in Figure 1C, the
axes 20A, 22A of the grooves 20, 22 are parallel and are
15 separated from each other by a distance 32 which is at
least slightly larger than the diameter D of the fiber 12,
thereby to prevent their touching as they rep~se in the
grooves. Although a more precise definition of the spacing
32 of the grooves is set out hereinafter (Figure 4), it
20 should be noted that in the case of a single movable fiber
(Figure 1) the magnitude of the separation distance 32 is
not as critical as in the case of plural movable fibers. It
lies within the contemplation of the present invention to
arrange the axes 20A, 22A of the grooves 20, 22 such that
25 they subtend a predetermined angle (on the order of one
degree) therebetween.
The fiber 12 has an end face 12E (Figure 1E),
preferably defined by cleaving the fiber 12. In practice, a
3 0 suitable anti-reflection coating, such as a one-quarter
wavelength thick layer of magnesium flouride, is provided
on the end face 12E.
The fiber 12 has a first predetermined portion 12F
35 (perhaps best seen in Figures 1D and 1E) defined adjacent
Sl~13StlTUTE SHEET
. ~ .
; ' . . :
'~091~6
WO 92/0~460 t O PCT/US91/06749
to the end face 12E thereof whil~ a second pred~termined
portion 12R (perhaps best s~en in Figure 1D) is dcfined a
predetQrmined distance rearwardly from the first portion
12F. The first portion 12F of the fiber 12 may be viewed
5 as that portion of the fiber 12 extending between the rear
surface 18R of the block 18 and the end face t2E. The
first portion 12F of the fiber 12 has a central axis 12A
(Figure 1 E) extendin~ thsrethrou~h.
In the embodiment shown in Figure 1, h~o
stationary optical fibers F1, F2 are fixed in a manner such
that they romain in place in a respective V-grooves 20,
22. For example, the stationary fibers F1, F2 may be
secured to another block 30 (indicated in dot-dash lines in
15 Figure 1D) using a ultraviolet light curable resin such as
that sold by Dymax Corporation, Torrington Connecticut as
Dymax 305. Another suitable adhesive is that sold by
Electro-Lite Corporation, Danbury, Connecticut under the
product number 82001-ELC-4480. The portion of the fixed
20 fibers extending into the grooves 20, 22 is also secured
into the block 18, with care being exarcised to prevent the
adhesive from reaching the region of the grooves into
which the movable fibers are disposed. The block 30 may
be mounted on or formed integrally with the base 14. The
25 cleaved end faces of the fibers F1, F2 may be provided
with anti-reflection coatings, such as that discussed
above. Of course, it should be understood that if a simpler
on-off switch arrangement is desired, one of the fixed
fibers F1 or F2 may be omitted.
In a first switch position (Fisure 1 A) the first
predetermined portion 1 2F of the fiber 12 is received
within a first one of the grooves 20, 22, as the case may -
be. Although not completely visible from Fi~ure lB, in the
3 5 second switch position the same predetermined portion ~ -
SU8STITIJTE SHEET
.
- . .
.. ~. . . .. . . - ~ .
- .. .. . , .
... . ~
,, . . . . ` . : . - . : . : .
... . . . . . . .. . .
W092/0~460 1 t ~9~6 PCr/US91~0674~
12F of the fiber 12 is received within the other of the
grooves 20, 22. When in each switched position the and
face 12E of the movable fiber 12 lies within a
predetermined close distance 34 (Figure 1E) of the end
5 face of the fixad fiber F1, F2 (as the case may be3 disposed
in that groove.
In the embodiments of the invention shown herein
the first portion 12F of each movable fiber 12 has an axial
10 dimension such that, when the fiber is in any switch
position, the end face 12E of the fiber lies within a
groove, intermediate the surfaces 18F and 18R of the
block 18. The first portion 12F of the fiber 12 has an
axial length typically between 0.25 millimeters and 0.40
15 millimeters when the axial length 18L of the block is on
the order of 1.5 millimeters The gap 34 is on the order of
approximately sixty-five (65) micrometers.
It should be understood, however, that the first
20 portion 12F of the fiber 12 may have an axial length such
that, when the fiber is in either switch position, the end
face 12E of the fiber 12 and some region of the first
portion 12F projects from the groove in which it is
disposed beyond ~he face 18F of the block 18. The
25 projecting end 12E of the fiber 12 may be placed in optical
communication with either another fiber or with any
active or passive opto-electronic device. The hypothetical
fiber or the hypothetical opto-electronic device is
suitably supported by any convenient expedient. The
30 support arrangement for the fiber or the device may be
attached to or made integral with the base 14. As a yet
further alternative, it should be understood that the first
portion 12F of the fiber 12 may have an axial length such
that, when the fibar is in either switch position, the end
35 face 12E of the fiber lies coplanar with the surface 18F of
S~BS~ 5~EE~
, ~ .
.. ~
WO 92/0~'160 1 ~ ~) 31~ ~ 6 PCI/US9~0674'~
the block 18. In such an arrangement either the
hypothetical optical fiber or the hypothetical opto-
electronic device may be secured to the surface 18F of the
block 18, eithsr directly or by a suitable mounting
5 arrangement.
Secured to the base 14 a predetermined distance 36
(Figure 1D) from the block 18 is a support pedestal 38.
The support pedestal 38 may be mounted on and secured to ~ -
10 the base 14 or may be formed integraliy therewith, as is
illustrated. The support pedestal 38 has a generally
inclined ramp surface 40R and a frontal surface 40F
thereon. As will be discussed the ramp surface 40R
serves to develop a biasing force in the fiber 12. This
15 function is best served if the ramp surface 40S is inclined
at a predetermined angle 42, measured as shown in Figure
1D. In practice the angle 42 IjBS in the range from five (~)
to fifteen (15~ degrees.
The second prsdeterrnined portion 12R of the
movable fiber 12 extends over the ramp surface 40S. The
ramp surface 40S may be provided with a Qroove 44 in
which the second portion 12R of the fiber 12 is received.
In either event the contact point at which the fiber 12
last touches the frontal surface 40F of the pedestal 38 is
indicated by the reference character 46. The portion of
the fiber 12 extending past the contact point 46 to the end
face 12E is termed the ~free length" of the fiber.
The fiber 12 is secured in the groove 44 (or on the
ramp surface 40S of the pedestal) at least in the vicinity
of the contact point 46. Any suitable expedient, such as
one of the adhesives mentioned earlier, may be used. The
adhesive is indicated by the referenca character 48
(Figures 1A and 1B).
SaJBSTlTUTE SHE~:~
. . .
,
.
. .
9 1 ~
W042/0~460 1 3 PCI~tUS91/0674')
As is bost illustratod in Fi~ure lD the contact point
46 lies a predetermined offset distance 50 above the
bottom of the grooves 20, 22. The axis 12A of ths portion
5 12F of the fiber 12 defines a predetermin~d angle 52
(Figure 1E) with respect to the axis 20A, 2?A (as
appropriate) of the groove 20, 22. The angle 52 must be
positive (i.e., above a reference plane P that is disposed
parallel to the surface of the base 14 and includes the
10 axis of the groove) and is related to the clearance
distance 36, the offset distance 50 and the pedestal angle
42 in accordance with the small angle approximation (in
radians):
A = B- 1.5 (B- HJL),
with A representin~ the angle 52,
B representing the angle 42,
H representing the offset distance 50, and
L representing the clearance distance 36.
In practice, the angle 52 is on the order of onP (1) degree.
As seen from Figure lD, the axes of the fixed fib~rs
25 F1, F2 are arranged parallel to the axis of the groove in
which they are disposed. However, it should be understood
that the axes of the fixed fibsrs F1, F2 may also be
inclined with respect to the axis of the grooves, similar
to the inclination of the movable fiber 12. This condition
30 is suggested in Figure 1E. To this end, it may be desirable
to slightly incline the block 30 (Figure 1D) in order to
cause a bending in the fibers and thereby to obtain a
biasing force thereon similar to the biasing force 56
imposed on the movable fibers, as will be discussed. This
3 5 alternative arrangement eliminates the adhesive
Sl~E~STlTVT~ S~EET
. - , :
,
- . -
~Yl~
W0 92/05460 14 PCI/US91/0674'~
attachment of the fixed fibers in the grooves of the block
1 8.
Owing to the disposition of the first portion 12F in
the groove 20, 22 and the second portion 12R on the ramp
surface 40S (including bein~ disposed in the gr~ve 44
therein) the fiber 12 bends throughout its free length with
the curvature being largest closer to tha pedestal 38.
This bending of the fiber 12 serves to impose a biasing
force acting on the first portion 12F ther~of. The biasin~
force acts in a direction 56 urging the first portion 12F of
the fiber 12 toward the bottom of the respective groove in
which it is disposed. The biasing force thus acts in a
direction 56 that is orientad generally perpendicularly to
the top surface 18T of the block 18.
A switching member, diagrammatically indicated by
the reference character 62, is operatively connected
(Figure 1B) to an actuator 64 for reciprocating movement
with respect to the base 14 in opposed directions 66A,
66B. The reciprocating motion of the switching member
62 in the directions 66A, 66B is in a direction generally
transverse to the direction 56 of the biasing force and to
the axis of the grooves 20, 22. The switching member 62
- 25 is disposed in the clearance space 36 provided between
the block 18 and the pedestal 38, preferably as close to
the rear surface 18R of the block 18 as possible.
Structural details of the preferred form of the switching
member 62 and the actuator 64 are set forth hereinafter.
In general, the switching member 62 takes the form
of a yoke having a crossbar 70 and a first and a second
arm 72A, 72B thereon. The arms 72A, 72B are spaced
apar~ a distance 74 sufficient to accept and to act against
35 a portion of the intermediate region 121 of the fiber 12,
SUBSTITUTE SH~T
, , -` ..
,-~ - ~ ' ,, :- `
- ., ;. .,, . ~ ` ., ~,.. ,.,
,`. . . ~ .,
9 ~
wos2/0;46n 1 5 Pcr/uss
that is, the region of the fiber intermediate the pedestal
38 and the block 18. The spacin~ 74 is such that the arms
72A, 72B do not contactthe fiber, other than when
imparting a switching force thereto. A more precise
definition of the spacing 74 bstween the arms 72A, 72B as
well as a discussion of the the distance of travel of the
switching yoke 62 is ~iven hereinafter.
The motion of the switching yoke 62 is limited by a
1 û suitable abutm~nt arran~sment, also to be described,
diagrammatically illustrated in Fi~ure 1 B by the reference
character 76. As will be discussed the abutment
arrangem~nt 76 nceds to be only coarsely aligned
inasmuch as it is not responsible for precise alignment of
15 the optical fiber. As noted, precise alignment of the fiber
is accomplished by the V-grooves.
Wi$h reference to Figures 1A, 1B and 1F, the
switching action of the switch 10 of the present invention
20 may be more fully understood. With the first portion 12F
of the fiber 12 disposed in the first groove 20, the
switching rnember 62 is displaced by the actuator 64 in an
initial direction 66A. The arm 72A is thus brought into
engagement with the portion of the intermediate region
25 121 of the fiber 12 Iying close to the block 18. The
switching force is thus transferred by the arm 72A to the
fiber 1 2.
As may be better appreciate~ from Figure 1F the
30 camming reaction betwesn the sidewall 20W2 of the
groove 20 and the first portion 12F of the fiber 12 causes
the same to be lifted out of the first groove 20. The
lifting motion is indicated by the character 78 and occurs
against the action of the biasing force 56. Continued
35 motion of the switching membsr 62 in the direction 66A
SU8S'r1TllT SH~ET
.
.. .
. .
. ?
, . '': , ' ', ' . ' ` : '', ,` ~ . ,, :
: - : . ~ . :
2091~5~
~V092/0~460 1 6 PCT/US91/0674'J ~1
causes the fiber 12 to transverse th~ median 18M (if
provided) and brings the first portion 12F of the fiber 12
into the mouth of the other groove 22. The biasing force
acting in the direction 58 urges the portion 12F of the
5 fiber 12 toward ttle bottom 22B of the other groove 22.
This motion is indicated by the character 80.
As may be appreciated ~rom the fore~oing the end
~?E of the fiber 12 thereby travels along a generally
10 semicircular path from its position of repose in the first
groove 20 (Figure 1A) to its position of repose in the
second groove 22 (Figure ~B). The ratcheting motion
caused by the re-seatin~ of the blased fiber 12 into the
bottom of the adjacent groove as the fiber 12 is traversed
15 across the block 18 provides a detent action that
positively places the fiber into a succeeding groove. The
alignment of the fiber 12 when in either the first or the
second (and any subsequent) positions is, as noted,
imparted by the sidewalls acting against the fiber 12. Of
20 course, the motion of the switching member 62 in the
reverse direction 66B reverses the switching of the fiber
12 from the groove 22 to the groove 20 in an analagous
manner. In each case the abutment arrangement 76 limits
the range of motion of the switching member 62.
It is apparent from the foregoing that, in accordance
with this invention, the switching force is transmitted by
the switching member 62 directly to the fiber 12. This
circumstance is to be distinguished from the mechanical
30 switch arrangements of the prior art in which the
switching force is applied to the member on which the
fiber is attached. Since only the mass of the actuator and
the relatively less massive fiber is being displaced, the
switching action in accordance with the present invention
SU8~;TITVTE SHEET
- . ~.
., - . - . - -
... . .. . . .
~ u ~
W092/0~460 ` .1 7 PCl/US91/06749
may be effected with relatively high switching spe~d, on
the order of about two milliseconds.
To facilltate the motions of th~ discussed in Fi~ure
5 1F the free length of the fiber, the angle 42 of the ramp
surface 40S, and the offsst distance 50 must be sized to
provide sufficient force to overcome friction between the
fused silica optical fiber and the material of the block 18
without breaking or cracking the optical fiber under
10 bending stress. In the preferrsd embodiment it has been
found that if the free length is about 1.4 centimeters, the
offset distance 50 should be about 0.0~6 centimeters
above the V-groove when the angle 42 of the ramp is about
ten ~10) degrees.
1 5
It should be rcadily appreciated from the foregoing
that more than two grooves may be disposed in the block
18 and that the fiber 12 may be switched to any selected
one of the grooves depending upon the magnitude of the
20 displacement of the switching member 62. Moreover, it
should also be understood that the principles of the
prssent invention may be extended to switch arrangements
having more than one movable fiber therein. Accordingly,
attention is now invited to the switch arrangements
25 -shown in Figures 2 and 3.
In th~ embodiment of Figures 2A and 2E~ the block
18 has three V-shaped grooves 20, 22, and 24 provided
therein. Tha axes of the grooves 20, 22 and 22 aro each
30 spaced apart a distance 32 that is on the order of the
diameter D of the movable fibers 12, 12'. Two stationary
optical fibsrs F1, F2 are again fixsd so as to remain in
place in two of the V-grooves 20, 22. Two movable
optical fibers 12, 12' are mounted on the ramp surface
35 40S of the support pedestal 38 (not shown in Figure 2B) in
SUBSTITUTE SHEET
-: - . ~ :: :. . . :
W092/0~460 1 8 PCr/l,lS91/Ofi74~ (~
respactive grooves 44, 44' thereon. The fibers 12, 12' are
thus each bent and, in the manner discuss~d in connection
with Figure 1, a biasing force 56, 56' is thereby ~enerated
ur~ing the first portion 12F, 12F of each of the fibers 12,
5 12' into the respective first V-grooves 20, 22.
The end faces 12E, 12E' of the fibers 12, 12' lie
aligned with each other and are also positioned in
confrontational relationship with the cleaved ends of the
10 fixed fibers F1, F2.
To switch the fibers 12, 12', the actuator 64 is
asserted, and the arm 72A of the switching member 62
engages the fiber 12. Since the grooves are spaced apart a
1~ distance substantially equal to the diameter D of the
movable fibers 12, 12', as the fiber 12 begins a
semicircular movement (Figure 1F, Figure 4) similar to
that discussed above the first portion 12F of the first
fiber 12 abuts against the second fiber 12' tsee, Figure
2 0 4A, 4B). This abutting action transmits the switching
force to the second fiber 12' and causes the same to
begins its semicircular motion. In this manner each fiber
12, 12' is moved into an adjacent groove. The
displacement of the switching member 62 is again limited
25 by the abutment arrangement 76 (Figure 2B). Again it is
noted that the abutment arrangement 76 needs to be only
coarsely aligned inasmuch as precise alignment of the
resp~ctive movable and fixed fibers is accomplished by
the V-grooves.
Figures 3A and 3B illustrate a yet further
modification to the embodiment of Figures 1A and 1B. In
the arrangemont of FiglJre 3A and 3B, the block 18 has four
grooves 20, 22, 24, and 26. An additional crossover fiber
3~ 90 is disposed in a crossover switch configuration. A
Sl)8STlTUTE SHE~
.. . . . ~ ~ , ,
~9~6
W092t1)5460 ~ 9 PCl/l~'S91/0674
crossover switch configuration is useful to bypass an
inoperative node in a network. One end 90E1 of the fi~er
90 is secured into the groove 26, as by mounting the same
to the block 30, such that the cleaved end face 90E1
5 thereof is in alignment with the snd faces of the other
stationary fibers Ft, F2. The cleaved end face 90E1 may
have an anti-reflection coating thereon.
The fiber 90 is looped and inclines over the ramp
10 surface 40S, thereby imparting a bend thereto and
generating a biasing force imposed on the end 90E2
thereof. A groove 44~ may b~ provided on the ramp surface
40S to rsceive the fiber 90. The portion nf the fiber 90
near to the end 90E2 thereof, the fiber 12, and the fiber
15 12' move as a group from groove to groove, in a manner
directiy analagous to that plural movable fiber
embodiment already discussed in connection with Figure 2.
The disposition of the group of fibers when moved to a
switched state is illustrated in Figure 3B.
With reference now to Figures 4A through 4C, shown
are diagrammatic illustrations of the considerations
attendent upon the spacing 74 between the arms 72A, 72B
of the yoke 62 and the distance of travel thereof.
25 Consider two movable fibers 12, 12', each having a
diameter D, arranged in a two fiber switching arrangement
(Figures 2A and 2B). The distance 32 (Figure 1C) between
the axes of adjacent grooves is the distance D + d, where d
is a smali offset distance between the fibars 12, 12'.
Tln practice the fiber 12 must be pushed past the
top of the adjacent groove by an amount E so that it will
slide down the incline of the sidewall of the adjacent
groove against ~riction. Adding all the length segments, it
SUBSTITVTE S~
.~ . . . .. ~ . ~ .
2U9~
WO 92/0~460 2 0 PCltUS91/Ofi74~ ~J
is clear that the minimum practical spacing 74 of the yoke
62 is given by the relationship:
Spacing 74 = 2.5 D + dl2 - E + 2e.
The character "e~ represents an additional increment since
it is desired that the arms 72A, 72B not touch the fiber
after the switching action is complete. However, it is
aooarent that if precise control of the yoke motion can be
10 attained, the absolute minimum spacing for the gap 74 is
given by the relationship:
Absolute Minimum Spacing 74 = 2D ~ d + 2e.
15 It is readily apparrent that these teachin~s as to the
minimum spacing dsitance 74 may be extended to
switches employing more than two fibers.
The displacement distance of the yoke is indicated
20 in Figure 4. The starting and ending positions of the yoke
are selected for reliable switchin~ operation.
From the foregoing it is seen that Figure 1
illustrates the manner in which a switch 10 in accordance
25 herewith may be implemented in an on-off configuration
or in a 1 x2 configuration. Similarly the implementation of
the switch of the presen~ invention in a 2x2 configuration
may be readily understood from Figure 2. Figure 3, as
noted, illustrates a crossover bypass switch
3 0 configuration. Extensions to other switch configurations
should be readily apparent to those skilled in the art.
With reference now to Fi~ures 5A, 5B and 5C, shown
are perspective, plan and side sectional views of a
SUBSTITIITE ~HE~T
:. ~
.
.
WO 92/0~460 ~ 1 3 ~ PCT/US91/0674
practical implementation of a switch in accordance with
the invention.
The above-discussed elements of the switch 10 ars
5 molded integrally within a housing ~enerally indicated by
the character 11 0 from a po!yester engineering
thermoplastic resin material such as that manufactured
and sold by E. I. Du Pont de Nemours and sold under the
trademark "Rynite~. The housin~ 1tO has an upstanding
10 sidewall 112 that surrounds and encloses the base 14.
The top of the sidewall 112 has a ~roove 114 that en~ages
a bead provided in the undersurface of a cover (not shown).
The cover 16 (not shown) is configured to close all open
areas of the switch housing 110 shown in Fi~ure 5A, and
15 thereby protects the interior of the switch. Tha cover is
glued in place, using any suitable adhesive, such as the
adhesive sold by Loctite Corporation, sold as product
number 404. The blocks 18 and 30, the pedestal 38 and the
other of the elements above described are integrally
20 formed with the base 14.
The sidewall 112 is interrupted at opposed ends
thereof by a first and a second fiber support shelf 116,
118, respectively. Each shelf is grooved, as at 116G,
25 118G, and respectively defines a support plafform
whereby the movable fibers 12, 12' and the fixed fibers
F1, F2 may enter the switch housing 110. The fibers are
glued to the shelves 116, 118 (e. g., using the last-
mentioned adhesive~ and a strain relief heat shrink tubing
30 used thereover.
Since the movable fibers 12, 12' enter the housing
110 with their jackets in place a transition pedestal 120
is disposed adjacent to the padestal 38. The transition
35 ped6stal 120 is grooved, as at 122G, with the grooves
~J~35~1~UT~ SH~
: , . ,. ,. . ,.- :........... . ..
; . : .- ~ : . ::
.
~VO9~/0~460 `~ 314~6 22 PCI/US91/0674
bending toward th~ inl~ts of the ~rooves 44 on ths ramp
surface 40S. The purpose of the transition pedestal 120
is to provide a space within the body of the switch 10
wherein the stripped fibers 12, 12' may be arranged prior
5 to their introduction onto the ramp surface 40S. Since the
fixed fibers F1, F2 also en~er the housin~ with their
jackets in place, a transition pedestal 122 adjacent to the
support plate 118 serves a similar function ~or these
fibers .
1 0
A gap 124 is defined between the block 30 and the
block 18. This gap 124 prevents epoxy adhesive from
flooding the grooved surface of the block 18.
1~ A pocket 130 is formed on the interior of the
housing 110. The actuator 64 (Figures 5B, 5C) is received
in the pocket 130. The actuator 64 is preferably
implemented using a solonoid actuator such as that
manu~actured by Aromat Corporation, New Providence,
20 New Jersey and sold as model TN2E-5V. Power is applied
to the actuator 64 via leads 64L extending through
openings formed in the base 14 (Figure 5C). With
particular reference to Fi~ures 5B and 5C, the actuator 64
includes a bar 132 that is pivotally mounted on a r~d 134.
25 Fnergization of the coils of the actuator causes mction of
the bar 132 in the opposed directions 134A, 134B.
Attached to the bar 132 is a generally L-shaped
bracket 136. The long side 136L of the bracket 136 is
30 attached to the bar 132 by any suitable means of
attachment. The short leg 136S of the bracket 136 has a
cutout that serves to define the yoke shaped switching
member 62 illustrated in the other drawing Figures. The
opposed reciprocating motions 134A, 134B of the bar 132,
35 when transmitted to the bracket 136, impart the generally
- SU8STITVTE S~E~T
-
. .
~9~6
W O 92/0~460 2 3 P ~ /US91/0674')
transverse switching motions 66A, 66B of the switching
member 62.
In the preferred instance the abutment arran~ement
76 limiting the motion of the switching member 62 is
dcfined by a pair of locating screws 140A, 140B. The
screws 140A, 140B are threaded through the sidewall 112
of the housing 110, and act against the surface of the long
arm 136L of the bracket 136. It should be understood that
10 the adjustable screws 14ûA, 140B are provided to
accommodate tolerances introduced during the
manufacture of the switch. With tighter manufacturing
control it may be possible to use fixed surfaces on
theinterior ofthe housing as the abutments sur~aces.
1 5
Those skilled in the art, having the benefit of the
teachings of the present invention as hereinabove set
forth may effect numerous modifications thereto. It
should be understood that such modifications are to be
2 0 construed to lie within the contemplation of the present
invention, as defined by the appended claims.
- SU8STl'rUl"E SHEET
- .. - , . . ~ - .................. , ~ .. . ..
.. . , .. - - .
- ~ ~ - . . .
