Lucent Technologies Inc.

Alcatel Lucent

At&t Bell Laboratories

Gm Global Technolgoy Operations, Inc.

At+t Corp.

American Telephone and Telegraph, Co.

Andrew Roman Chraplyvy

Robert William Tkach

Peter Johannes Winzer

Xiang Liu

Robert Meachem Jopson

Fabrizio Forghieri

Christopher Richard Doerr

Kenneth L Walker

Sethumadhavan Chandrasekhar

Alan H Gnauck

Thomas L Koch

Jan F Herbst

Chandrasekhar Sethumadhavan

John J Croat

Stojan Radic

Thomas Andrew Strasser

Patrick P Iannone

Jonathan A Nagel

Ivan P Kaminow

John L Zyskind

Julian Stone

James W Sulhoff

Lawrence Warren Stulz

Atul Kumar Srivastava

David Kalish

Yan Sun

Colin J McKinstrie

Bernard Raymond Eichenbaum

Tingye Li

Lynn E Nelson

Dean C Hammond, Jr

Raymond Bradfield Kummer

George W Newsome

Joseph Carmine Centanni

Janice Bilecky Haber

Xiaoping Mao

John C Ellson

Julian M Tishkoff

Gary Patrick Emery

Alan H Gnauk

A spatially multiplexed optical link having a plurality of transmission paths, wherein at least one transmission path is configured to carry an optical-pump signal while one or more other transmission paths carry data-bearing signals. Disposed within the optical link are an optical signal-distribution module and an amplifier module. The optical signal-distribution module is configured to couple portions of the optical-pump signal into the data-bearing transmission paths. The amplifier module is configured to amplify the data-bearing signals using these portions of the optical-pump signal as a power source in a suitable all-optical amplification scheme. The optical-pump signal can optionally be tapped and applied to a photovoltaic element configured to directly power a device, e.g., an optical performance monitor, or to charge the battery of that device to enable its autonomous operation if external electrical power is not available where the device is deployed.

Optical pumping and powering in spatially multiplexed transmission links

An example apparatus comprises an optical transmitter which includes a first processor and at least two optical modulators. The first processor is configured to generate a first electronic representation for each of at least two optical signals for carrying payload data modulated according to a one-dimensional (1-D) modulation format, and to induce on respective ones of the first electronic representations an amount of dispersion that depends on a power-weighted accumulated dispersion (AD) of a transmission link through which the at least two optical signals are to be transmitted thereby generating complex-valued electronic representations of pre-dispersion-compensated optical signals. Each of the at least two optical modulators modulate a respective analog version corresponding to a respective one of the complex-valued electronic representations onto a polarization of an optical carrier.

Communication through multiplexed one-dimensional optical signals

An apparatus comprises an optical transmitter that comprises a processor and at least one optical modulator. The processor is configured to generate electronic representations of at least two pre-dispersion-compensated phase-conjugated optical variants carrying a same modulated payload data for transmission. The at least one optical modulator is configured to modulate the electronic representations, wherein an amount of dispersion induced on the pre-dispersion-compensated phase-conjugated optical variants depends on an accumulated dispersion (AD) of a transmission link through which the pre-dispersion-compensated phase-conjugated optical variants are to be transmitted. The amount of dispersion induced on the phase-conjugated optical variants may be approximately &#x2212;AD/2, where AD is the accumulated dispersion of the transmission link. The pre-dispersion-compensated phase-conjugated optical variants are different from one another in one or more dimensions such as the polarization of light, the time of transmission, the spatial localization, the optical carrier wavelength, or the subcarrier frequency during transmission.

Communication through pre-dispersion-compensated phase-conjugated optical variants

An optical transmitter configured to perform digital signal equalization directed at mitigating the detrimental effects of a frequency roll-off in the transmitter's optical I-Q modulator. In various embodiments, a frequency-dependent spectral-correction function used for the digital signal equalization can be constructed to cause the spectrum of the modulated optical signal generated by the transmitter to have a desired degree of flatness in the vicinity of an optical carrier frequency and/or to at least partially mirror the frequency roll-off in the optical I-Q modulator.

Frequency equalization for an optical transmitter

An apparatus receives data encoded in a format where information bits for transmission are mapped into symbols each carrying a plurality of bits, some of which are encoded through a frequency-shift keyed (FSK) format and the rest of which are encoded through an additional modulation format on at least one FSK carrier. The receiver detects the signal through a dual-polarization coherent receiver front-end, and recovers polarization components of the signal by decoding a first non-zero portion of a plurality of bits carried by a symbol based on frequency slot position of at least one FSK carrier in the polarization components and a second non-zero portion of the plurality of bits carried by the symbol based on the additional modulation carried by at least one FSK carrier in the polarization components. Pilot-assisted orthogonal frequency-division de-multiplexing (PA-OFDM) may be used for spectrally-efficient signal reception, even in the presence of severe FSK errors.

System, method and apparatus for high-sensitivity optical detection

An optical transport system configured to transmit a set of two or more optical variants per bit-word, with the optical variants in the set being different from one another in one or more of the time of transmission, spatial localization, polarization of light, carrier wavelength, and subcarrier frequency. Differences between the optical variants may also be due to different respective constellation mapping. The optical variants of each set are detected and processed at the receiver in a manner that enables coherent summation of the corresponding electrical signals prior to constellation de-mapping. The coherent summation tends to average out the deleterious effects of linear and nonlinear noise/distortions imparted on the individual optical variants in the optical transport link because said noise/distortions are incoherent in nature. A BER reduction enabled by the use of optical variants may be implemented in addition to or instead of that provided by FEC coding.

Performance enhancement through optical variants

A method of multiple-band switching using a multi-pump fiber parametric switch is demonstrated. The switching architecture combines parametric band amplification, wavelength conversion and selective signal conjugation, enabled by temporal control of at least one pump of the multi-pump parametric device. The switching speed of the present invention is limited by the rise time of the controlled pump(s).

Method and apparatus for multi-band optical switching using multi-pump parametric devices

A multi-channel optical equalizer for intersymbol interference mitigation compensates for single- or multi-wavelength channels simultaneously and requires few adjustable parameters. The optical equalizer also compensates for overshoots and signal transition degradations in semiconductor optical amplifiers. The equalizer unit uses one control signal for magnitude and one to control signal phase. The equalizer includes a controllable coupling ratio coupler for splitting the light into two portions and a controllable interferometer having two arms, one arm having an additional delay which is equal to an integer multiple of 1/&#x394;f, where &#x394;f is the channel spacing between adjacent wavelengths utilized in the optical system. The controllable interferometer has a controllable delay in a first or second arm for adjusting the relative phase of the light passing therethrough. A coupler combines the two signal portions from the first and second arms to form the equalized output signal. A multistage optical equalizer is implemented using a plurality of optical signal equalizers.

Optical equalizer for intersymbol interference mitigation

A multi-pump phase modulator apparatus and operating method uses only one phase modulator to eliminate SBS without degrading idler(s). The single phase modulator phase modulates multiple pump signals to form multiple phase modulated pump signals using a modulation signal having a modulation period. A delay apparatus delays a first wavelength group by the modulation period relative to other wavelength groups. A combiner combines the delayed first wavelength group with the other wavelength groups to form a combined modulated multiple pump signal. In one embodiment a multi-pump phase parametric apparatus comprises the multi-pump phase modulator apparatus combined with a parametric apparatus to generate an amplified input signal and one or more idlers. Other embodiments of the multi-pump phase conjugator apparatus are used as part of an Optical Switch, Sampler, Tributary Extractor, and Regenerator.

Multiple pump parametric apparatus having no idler broadening

A multi-channel optical equalizer for intersymbol interference mitigation compensates for single- or multi- wavelength channels simultaneously and requires few adjustable parameters. The optical equalizer compensates for overshoots and signal transition degradations in semiconductor optical amplifiers. The equalizer unit uses one control signal for magnitude and one to control signal phase. The equalizer includes a controllable coupling ratio coupler for splitting the light into two portions and a controllable interferometer having two arms, one arm having an additional delay which is equal to an integer multiple of 1/&Dgr;f, where &Dgr;f is the channel spacing between adjacent wavelengths utilized in the optical system. The controllable interferometer has a controllable delay in a first or second arm for adjusting the relative phase of the light passing therethrough. A coupler combines the two signal portions from the first and second arms to form the equalized output signal.

Multi-channel optical equalizer for intersymbol interference mitigation

An improved multi-channel optical equalizer method and apparatus for intersymbol interference mitigation compensates many wavelength channels simultaneously and requires few adjustable parameters. The equalizer unit has only two control signals, one to control signal magnitude and one to control signal phase, yet it can still compensate many wavelength channels simultaneously. The equalizer includes a coupler with a controllable coupling ratio for splitting the light into two portions and a controllable interferometer means having two arms, one arm having an additional delay which is equal to an integer multiple of 1/&Dgr;f, where &Dgr;f is the channel spacing of the multiwavelength system. The controllable interferometer unit also has a controllable delay in a first or second arm for adjusting the relative phase of the light passing therethrough. A coupler combines the two signal portions from the first and second arms to form the equalized output signal.

An optical transmission system exploits the reduced signal-to-noise (SNR) requirements for low-bit rate channels to devise a new wavelength channel allocation scheme which increases the number of channels that a WDM system can support. Wavelengths of low-bit rate channels are assigned outside a flat-gain window (i.e., flat-passband region) of the system. The channel allocation scheme uses the high-bit rate channels located in the flat-passband region of wavelengths and the lower-bit rate channels located outside this passband region with progressively lower-bit rate channels located farther outside this passband region. Low-bit rate channels are also assigned to region(s) of the passband where the non-linear threshold power level of the system may be exceeded.

Power and wavelength management for mixed-rate optical data systems

Substantially error-free communications is achieved in an optical communication system that includes optical amplifiers by detecting bits transmitted in the amplified optical signal using a detection threshold that is derived as a function of a maximum power level associated with a first bit value, e.g., bit &ldquo;0&rdquo;, and a minimum power level associated with a second bit value, e.g., bit &ldquo;1&rdquo;. Importantly, this detection scheme can be used to accurately detect bit patterns in the amplified signal even in the presence of nonlinear distortions caused by gain variations, such as inter-modal distortion and saturation induced crosstalk. In a wavelength division multiplexed (WDM) system comprising semiconductor optical amplifiers, for example, the detection threshold can be set at a level corresponding to P /2N, where P represents the total power in the WDM signal and N represents the number of optical channels in the WDM signal. According to another aspect of the invention, the effect of gain fluctuations becomes smaller as the number of channels increase. In particular, a smoothing effect is realized for the total effective saturation power as gain variations decrease as a function of an increase in the number of channels. As such, the performance of a semiconductor optical amplifier according to the principles of the invention approaches the linear performance of fiber amplifiers as the number of channels increases.

Lightwave communication systems using semiconductor optical amplifiers

Resonances in cross-phase-modulation (CPM) impairment occur in wavelength-division-multiplexed (WDM) transmission systems, having multiple equal dispersion-length amplifier spans, when channels have an integral number of bit walk-throughs per amplifier span. The CPM resonances are reduced by mis-matching the amplifier span lengths (and/or dispersion in each span) so an integral number of bit walk-throughs do not occur in successive amplifier spans. The CPM resonances are reduced by adding different lengths of dispersion-compensating fiber to each span, using different modulation bit rates and/or clock phase delay for each channel, and using different wavelength-selective clock phase delays for each channel.

Wavelength division multiplexed system having reduced cross-phase modulation

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Matawan, NJ, United States of America

Andrew Roman Chraplyvy