Alphion Corporation

Lucent Technologies Inc.

Roman Antosik

Bharat P Dave

Boris Stefanov

Ronald Simprini

Tan Buu Thai

Kwang S Kim

Doruk Engin

Jiten Sarathy

Julio Martinez

Olga Nedzhvetskaya

David Lidsky

Michael Evans

Jithamithra Sarathy

Richard L Ukeiley

Lewis K Stroll

Jayanta Das

Ganesh Lakshminarayana

Mohammad Laham

Carl A Caroli

Frank N Hujber

Chinnabbu Ekambaram

Andrew T Schnable

Aleksandr Miglo

Olga Nedzhvetska

Jayantha Das

Stanley E Wood

Ravi Vora

Frederick Renner

David Lowe

Khem Gandhi

Raj Acharya

Scott Kaminski

Kuo-Ming Lee

Tan Thai

Method and apparatus are presented for the generation and detection of maintenance signals in an optical data network. The maintenance signals are such that they can be read both by high bit-rate and low bit-rate receivers. Detection of the maintenance signals occurs in two stages. In a low bit-rate first stage each nodal input port is sampled in a round robin fashion to detect the presence of a maintenance signal. In a high bit-rate second stage the maintenance signal is verified and read by a high speed receiver, along with other high bit-rate information transmitted with it. One second stage high speed receiver is shared among M input channels for cost and circuit efficiency.

Generation and detection of optical maintenance signals in optical networks

The present invention provides an optical signal quality selection system for optimizing the quality of information transmission. The system splits an incoming optical signal into two equal signals. The split signals are evaluated in optical performance monitors, transmitting an electrical output message to a signal selector relating to the quality of the respective signal. A second electrical message is sent from the optical performance generator to an alarm indicator signal generator, which sends an optical signal to the signal selector to drop the one of the split signals and transmit the non-dropped split signal. An unequipped optical signal from an optical idle signal generator is triggered if no active optical signal is being transmitted.

Optical signal quality selection system

Circuitry for a node of an optical communication network has a mux and/or a demux. In one embodiment, the circuitry has a mux and a demux implemented on a single circuit board, where (1) the mux is configured to combine up to eight different incoming OC3/OC12-rate electrical signals into a single outgoing OC48-rate electrical signal for conversion into two copies of an outgoing OC48 optical signal and (2) the demux is configured to split a working incoming OC48-rate electrical signal (selected from two incoming OC48-rate electrical signals converted from two incoming OC48 optical signals) into up to eight different outgoing OC3/OC12-rate electrical signals. The node is configured to perform automatic signal provisioning, which may be (a) the addition of a new OC3/OC12 signal; (b) the deletion of an existing OC3/OC12 signal; (c) the rate-upgrading of an existing OC3 signal to an OC12 signal; or (d) the rate-downgrading of an existing OC12 signal to an OC3 signal. When adding a new OC12 signal or rate-upgrading an existing OC3 signal, the node automatically determines how to move existing OC3/OC12 signals within the OC48 frame in order to accommodate the new OC12 signal. The node automatically communicates with the other node corresponding to the provisioned signal to automatically initiate corresponding signal provisioning at the other node.

Circuitry for mixed-rate optical communication networks

Circuitry for a node of an optical communication network is configured to mux (i.e., combine) one or more incoming customer signals for transmission as a single outgoing optical signal and to demux (i.e., split) an incoming optical signal into one or more outgoing customer signals, where the muxing and demuxing clocks are selected from one or more customer clocks recovered from the one or more customer signals, an input clock recovered from the incoming optical signal, and a local clock generated by a local clock generator. When configured for an add/drop configuration, the circuitry selects (1) the muxing clock from the one or more customer clocks, the input clock, and the local clock and (2) the demuxing clock from the input clock and the local clock. When configured for a drop/continue configuration, the circuitry is configured to select both the muxing and demuxing clocks from either the first input clock or the local clock. The circuitry is configured to perform a hardware-based switch to select the backup clock as the new muxing clock upon detection of a loss-of-clock condition for the previously selected muxing clock. The node automatically coordinates its selection of muxing clocks with the other corresponding node in order to avoid loop-timing problems.

Timing circuitry for muxing/demuxing of optical communication signals

A method and circuit are presented for an all-optical format independent preprocessor that processes an arbitrary optical input signal by converting a NRZ signal to a PRZ signal, or if the input optical signal is RZ, by merely amplifying it. The method involves subtracting a delayed copy of the signal from the original, thereby effectively doubling its frequency, and inserting a pulse at each transition of the original signal, whether rising or falling. In a preferred embodiment this stage is implemented via an integrated SOA in each arm of an asymmetric interferometric device. The asymmetry consists of a delay element in one arm. In a preferred embodiment the entire device is fabricated on a semiconductor substrate, allowing for compactness as well as minimization of interconnectivity losses and overall power consumption. The output of the preprocessor, having a significant frequency component at its original clock rate, can then be fed to a clock recovery stage for all-optical clock recovery.

Format insensitive and bit rate independent optical preprocessor

A method and system for AO R functionality is presented. The system includes an AO R device followed by an AOCR clock recovery module and an AOR retiming device. The AOR retiming device takes as input a recovered clock signal extracted from the output of the AO R by the AOCR clock recovery module. The output is the recovered clock signal gated by the regenerated and reshaped input signal, and a monitor circuit is used to set the optimum operations of the retiming device. In a first embodiment the output of the AOR retiming device is fed to an AOC code and wavelength conversion output stage, which returns the signal to the NRZ coding, on a service wavelength converted to match the fixed wavelength connection with the DWDM transmission system. In a second embodiment the code conversion is incorporated into the AOR retiming device, and wavelength conversion is accomplished in the AOCR clock recovery device.

Bit-rate and format insensitive all-optical circuit for reshaping, regeneration and retiming of optical pulse streams

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Colts Neck, NJ, United States of America

Roman Antosik