Note: Descriptions are shown in the official language in which they were submitted.
CA 02453012 2003-12-12
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DISCLOSURE OF INVENTION
Disclosure Number DI: DI 031032
Date Received:
Received by: Melanie Budarick
Patent Committee Use
Inventor's Section
A. Administrative:
Title of Invention
Control of Tunable Optical Dispersion Compensation by Electronic Dispersion
Compensator
Inventor(s):
Name Signature Identify InventiveDate and Location
Contribution of
First Record
Arthur G. Inventor
Wilson
Please ensure each inventor Fisted above completes the attached information
nape.
Any delay in providing this information will cause a delay in awarding a stock
option
award for a conventional US patent application, where applicable.
B. Has any publication or disclosure to others been made, or has there been
any sale or
delivery of prototypes?
Yes 0 No
Details of prior This invention was accidentally disclosed to personnel from
Aegis
disclosure: Semiconductor (optical dispersion compensator potential source)
during a
conference call, though it was not identified as potential IP. Aegis did agree
that this was the most logical way to control such a device cost effectively
and
presented the idea back to JDSU is a subsequent confidential briefing.
C. Description
Answer all the following. (May be included with additional sheets)
i. In one sentence, what is the invention?
Utilizing both electronic and optical dispersion compensation within an
optical transceiver or
transponder module with the optical compensator setpoint driven by metrics
generated by the
electronic compensator.
LIST three to five (3 to 5) keywords that describe your invention.
Adaptive, receiver, "dispersion compensator"
DESCRLBE THE INVENTION IN DETAIL. Completeness is essential. Note that the
description given may be filed directly without editing in order to establish
priority. Use
extra sheets as necessary. The disclosure should be understandable by a non-
specialist
technical person. Diagrams are usually necessary to explain an invention
adequately.
This invention relates to 1 OG transponderltransceiver configurations which
are intended for use
in amplified systems at greater than 80 km, with a goal of at least the size
of a typical metro ring,
240 km. This invention ma also be a lied to 40G transponders/transceivers at
distances of one
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DISCLOSURE OF INVENTION
sixteenth those stated for 1 OG. Carriers wish to be able to upgrade existing
2.5G rings to 10G
without the task and expense of engineering, procuring, and installing passive
dispersion
compensation modules (typically packaged lengths of dispersion compensating
fiber) in the
transmission path. The logical approach is to integrate such compensation into
the optical
interface modules themselves.
Figure 1 compares the typical transponder (or transceiver, without the
electrical demux function)
implementation with the improved approach described herein. Traditionally, the
optical signal is
converted into an analog electrical signal by the photoreceiver, which may be
APD or PIN detector
based. The output of the photoreceiver may be further processed by a
postamplifier or clock and
data recovery circuit, which makes the received analog signal compatible with
following circuitry.
The following circuitry may be an electrical demultiplexer as shown for
transponder applications,
or the signal may exit the optical module at the Postamp output in transceiver
applications.
The improved approach adds an electrical adaptive filtering block (commonly
called EDC for
electronic dispersion compensation) and an adjustable optical dispersion
compensator. The EDC
block is now beginning to be implemented in transponders and transceivers, yet
current
generation EDC implementations only increase dispersion tolerance of the
optical interface by
approximately 50%. An 80 km interface then may be extended to 120 km,
insufficient to achieve
a full ring reach of 240 km. The control of the EDC block (filter tap weight
calculation) is normally
achieved by calculating quality metrics of the filtered eye, then optimizing
those metrics through
an associated controller running an algorithm (example: least mean square
error) which modifies
the weights to maximize eye quality.
It is not a stretch to extend the dispersion tolerance by adding an adjustable
optical dispersion
compensator in the optical path before the receiver: Normally, this block
would require manual
adjustment using equipment external to the optical interface module (BER
feedback, optical eye
monitoring, etc.). This compensator could be bragg grating, etalon, or all
pass filter waveguide
filter based. The invention is in automatically controlling the setpoint of
the ODC block with the
eye metrics developed by the EDC device, thereby extending the dispersion
tolerance
optimization range of the transponder/transceiver. It is expected that this
approach may be used
to extend the useful communication range of the transponderltransceiver to
beyond 500 km
without expensive dispersion compensator modules in the network, thereby
reducing carrier
capex (equipment costs) and opex (cost to engineer, install, and tweak the
DCMs and added
optical amplification required to overcome the losses in the DCMs) needed to
upgrade existing
rings to 10 Gbls. This approach is also valuable in a reconfigurable optical
network, where the
path may not be known a priori, and the combined approach allows the
transponderltransceiver to
optimize the path in real time after a path switch. The concept may be also be
extended to
control of adaptive PMD compensators, where historically the feedback for the
control loop uses
expensive and large optical PMD sensing. This would be particularly valuable
in 40 Gbls
interfaces.
iv. Describe the prior art
Previous implementations of dispersion compensation have typically been
optically based, with
either fixed, "set and forget' (non adaptive), or adaptive functionality based
on feedback from
direct measurements of the transmission path's optical chromatic dispersion or
statistics of
errored bits as determined by the receiver's FEC decoder if present. Non
adaptive solutions
cannot compensate for changes in' chromatic dispersion due to a reconfigurable
network's
changes in path length. Optical measurements are expensive and difficult to
implement within
shrinking transponderltransceiver physical envelopes, and FEC decoders are not
normally
accepted by the market as part of a transceiver or transponder.
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v. Identify what aspects of the invention need to be protected. Remember that
the purpose
of a patent is to PREVENT OTHERS from doing something.
The aspect of controlling a tunable optical dispersion compensation device by
the metrics
developed to control an electronic,dispersion compensator IC which is also
within the optical
transceiver/transponder module. Customers are already looking at using EDC to
help guarantee
interoperability at 80 km, and JDSIJ has evaluated concepts and prototypes of
transponders
which achieve extended reaches (200-500 km) by integrating tunable dispersion
compensation in
the optical domain. The adaptive approaches have relied on external error rate
feedback to train
and optimize the ODC setpoint.
vi. What is the status of the invention at JDSU? (May range from "in
production" to "concept
only')
Concept only at this time, awaiting the development of ODC subassemblies which
are cost
effective for single channel usage within a transponderltransceiver. The EDC
ICs are in
evaluation at JDSU. Overall concept likely to be implemented on JDSU LH
transponders to
achieve optimized BER performance at distances to 500+ km at 10 Gbls.
D. Dated at Melbourne, FL this day of
Arthur G. Wilson
Signature of Originator Print name
Read and understood by:
Witness (Print Name)
Signature of Witness Date
Management Section
Manager'slBusiness Unit Comments
I have renewed this submission and agree it presents novel approaches central
to protecting our
ongoing work in dispersion compensating component, module & system designs. I
fully support
this DI and advocate a patent filing. Ron Genova - VP Telecom BU
Rev August 12, 2002 Page 3
