Sycamore Networks, Inc.

Murat Azizoglu

Eric Arthur Swanson

Richard A Barry

Derek E Spock

Jianying Zhou

Jonathan C Bloch

Farzana I Khatri

Paolo L Narvaez

Naimish Patel

Kayi Lee

Thomas Kong

Vijayanand Vusirikala

Danny Hin-Kwok Tsang

John Z Jiang

A coding scheme is provided transporting encoded information over an optical communications link to a network. Multi-word information groups are analyzed to determine whether each of the information groups includes control characters. If the information group does not include any control characters, an encoded information stream including a set data indicator and data words is generated. If the information group includes one or more control characters, an encoded information stream is generated which includes control code counters, a transition indicator, location pointers, control codes that are encoded from the control characters, and any data. Accordingly, the necessary bandwidth for transporting the information is reduced by using this encoded information stream without sacrificing any control information.

Coding scheme using a transition indicator for signal transmission in optical communications networks

A method is provided for optical filter card design that facilitates a relatively efficient filter assignment algorithm solution resulting in a filter design that reduces a probability of unnecessary wavelength regenerations.

Method for designing optical filter cards

An optical amplifier for a 4-fiber system having two inputs and outputs is provided that makes use of a single amplifier rather than two separate amplifiers. The optical amplifier node makes use of an interleaver before and after the single amplifier to demultiplex and multiplex even and odd channel signals traveling in opposite directions. The arrangement can also amplify wide channel spaced signals traveling through a plurality of optical fibers. The optical amplifier node can be combined with other like amplifier nodes to provide more complex amplifier solutions at reduced costs due to the need for only half of the typical number of amplifiers. The optical amplifier node can also be combined with, e.g., variable optical attenuators, L/C/S filters, channel add/drop, co- and counter-propagating Raman amplification, and dispersion compensation modules to modify the optical signals as desired.

Two fiber support with single optical amplifier

A Dense Wavelength Division Multiplexed (DWDM) optical transmission system that compensates for unequal channel performance over an extended fiber transmission distance. The DWDM optical transmission system includes optical transmitters at a transmitter end of a transmission path for transmitting respective channels of information at different wavelengths, a first pre-emphasis device for performing a first pre-emphasis technique on the respective channels, an optical multiplexor for combining the respective channels into a multi-wavelength optical signal for transmission on a single transmission fiber, at least one optical amplifier for amplifying the optical signal along the path, at least one second pre-emphasis device disposed along the path for performing a second pre-emphasis technique on the respective channels, an optical de-multiplexor for separating the optical signal into its component channels, and optical receivers at a receiver end of the path for receiving and detecting the information carried by the respective channels. The first and second pre-emphasis techniques performed by the respective first and second pre-emphasis devices compensate for unequal channel performance along the transmission path over a desired fiber transmission distance.

Method and apparatus for extending fiber transmission distance with multiple pre-emphases in optically amplified DWDM system

A high speed DWDM optical transmission system that reduces a fiber dispersion limit without reducing the total channel count of a multi-wavelength optical signal. The system achieves such reduction in the fiber dispersion limit by employing a multi-wavelength optical signal comprising a gap-free band structure, and performing per-band dispersion compensation on the optical signal by adjusting residual dispersion values associated with one or more of the bands. In one embodiment, the system includes a first dispersion compensation module (DCM) that provides a dispersion-compensated multi-wavelength optical signal containing wavelength-dependent residual dispersion to a band splitter. The band splitter separates the dispersion-compensated optical signal into a plurality of bands such that no band gaps are formed between adjacent bands, and provides each band to a respective second DCM configured to reduce the residual dispersion associated with that band to a predetermined range of residual dispersion values.

Method and apparatus for per-band compensation with gap-free band structure for high speed DWDM transmission

Data transmission apparatus includes first and second optical transmitters coupled to an optical link. A forward error correction (FEC) coder is coupled to the input of the second optical transmitter. A first information signal having a first information rate is provided to the first optical transmitter, and a second information signal having a second information rate is provided to the second optical transmitter. The use of the FEC coder enables the second information signal to have a higher information rate than the first information signal, while simultaneously enabling the respective output power levels of the first and second optical amplifiers to be substantially equal. The data transmission apparatus achieves higher data transmission capacity while retaining compatibility with pre-existing fiber spans and amplifier nodes. An optical transmission system incorporates an optical transmitter and an optical receiver having certain transmission characteristics, such as output power level, decision threshold level, etc., that are adjustable in response to bit error rate information. A bit error rate estimator is provided at the receiving end of the optical link. The bit error rate estimator estimates the bit error rate of the received information signal, and provides bit error rate information to the optical receiver, and/or the optical transmitter, and/or the optical link, based on the estimated bit error rate, in order to optimize the performance of the transmission system.

Method and apparatus for improving transmission performance over wavelength division multiplexed optical communication links using forward error correction coding

Multiple gigabit Ethernet (GbE) and Fiber Channel (FC) signals are multiplexed and transported on a wavelength-division multiplexed (WDM) communications link using synchronous optical network (SONET) signaling. A transmitter decodes the 8b/10b encoded GbE/FC signals to reduce their respective signaling rates to no greater than the payload data rate of an OC- signal used on the link. The decoded signal are packetized into fixed-size packets in order to append a stream identifier used for de-multiplexing at the receive end. The packetized streams are multiplexed together and formatted into the OC- signal, which is transmitted over the communications link. A receiver de-multiplexes the received signal to obtain the packet streams, converts the packet streams to the corresponding decoded signals, and re-encodes each signal to re-create the original GbE/FC signals. A pair of interfaces can be arranged to provide independent adding or dropping of the GbE/FC signals that share the same wavelength.

Method and apparatus for transporting gigabit ethernet and fiber channel signals in wavelength-division multiplexed systems

An optical amplifier for a 4-fiber system having two inputs and outputs is provided that makes use of a single amplifier rather than two separate amplifiers. The optical amplifier node makes use of an interleaver before and after the single amplifier to demultiplex and multiplex even and odd channel signals traveling in opposite directions. The optical amplifier node can be combined with other like amplifier nodes to provide more complex amplifier solutions at reduced costs due to the need for only half of the typical number of amplifiers. The optical amplifier node can also be combined with, e.g., variable optical attenuators, L/C filters, channel add/drop, and dispersion compensation modules to modify the optical signals as desired.

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North Billerica, MA, United States of America

Murat Azizoglu