Ciena Corporation

Other

Huawei Technologies Co., Limited

Johns Hopkins University

Tektronix, Inc.

Michael George Taylor

Balakrishnan Sridhar

Vipul Bhatnagar

Michael J Ransford

Jeffrey C Livas

Minh T Nguyen

Jun Bao

Harshad P Sardesai

Joseph E Sluz

James E DeGrange, Jr

Curtis Robert Menyuk

Clark Scrandis

Michael L Dennis

Raymond M Sova

John W Zweck

Eric J Adles

David Tisherman

Sanjaykumar Upadhyay

Shuxian Song

Pool coping edge

A method and apparatus of compensating for compact digital domain chromatic dispersion. The distortion of an optical signal due to chromatic dispersion is compensated by a digital signal processing in the electrical domain, either prior to the optical transmitter or following the receiver. The circular coefficient approximation and sub-band processing reduce the amount of computations to execute a given level of chromatic dispersion compensation compared to a direct finite impulse response filter implementation.

Apparatus and method of compensating for compact digital domain chromatic dispersion

Embodiments of the invention include systems and methods for measuring or otherwise calculating polarization mode dispersion (PMD) of an optical fiber, or other device, by comparing the optical signal through the PMD element with the optical signal obtained directly from the transmitter, and calculating the PMD from the discrepancy between the two. Any distortions on the transmitter signal are effectively calibrated out, increasing measurement accuracy over conventional approaches.

Polarization mode dispersion measurement by observation of data-bearing signals

A universal optical receiver may include an optical channel monitor configured to acquire spectral data for an optical signal on at least one selected optical channel, a tunable local oscillator configured to be tuned to a center frequency of the optical signal on the at least one selected optical channel, a storage device configured to store data associated with the optical signal responsive to acquisition of the spectral data and tuning of the tunable local oscillator, and processing circuitry configured to execute an algorithm that employs a plurality of binary distinctions based on physical characteristics of the optical signal and employs at least one calculation of figure of merit associated with a series of parameter values of the optical signal to identify a format of the optical signal.

Cueing system for universal optical receiver

In an optical data transmission system, one channel is removed from a group of wavelength division multiplexed optical channels and another channel carrying different information at the same wavelength is inserted in its place. The process occurs by adding an optical signal whose electric field is the difference between the electric field of the new and old channels. The difference calculation takes into account the phase of the incoming WDM channel and phase of the laser source of the difference signal. The method has applications in optical transmission networks as add-drop nodes and optical regenerators, for generation of high bandwidth optical signals, and for secret optical communications.

Coherent optical channel substitution

The present invention is a method and apparatus to make an estimate of the phase of a signal relative to the local oscillator in an optical coherent detection subsystem that employs a digital signal processor having a parallel architecture. The phase estimation method comprises operations that do not use feedback of recent results. The method includes a cycle count function so that the phase estimate leads to few cycle slips. The phase estimate of the present invention is approximately the same as the optimal phase estimate.

Phase estimation for coherent optical detection

A method and system of coherent detection of optical signals. The system utilizes a digital signal processor to recover an incoming optical signal. The system employs a local oscillator, which does not need to be phase locked to the signal. The signal may be consistently recovered, even when the polarization state varies over time. Additionally, the signal may be recovered when it comprises two channels of the same wavelength that are polarization multiplexed together. In addition, any impairment to the signal may be reversed or eliminated.

Coherent optical detection and signal processing method and system

Chromatic dispersion in a high speed CS-RZ WDM transmission system is reduced by providing tailored 'precompensation' for individual and/or groups of optical signals. Such precompensation is achieved by passing the optical signals through a dispersion compensating elements, such as dispersion compensating fiber, within an optical multiplexer, i.e., prior to multiplexing the signals onto a single optical fiber. Additional dispersion compensation can be performed in optical amplifiers and within an optical demultiplexer downstream from the optical multiplexer.

WDM system having chromatic dispersion precompensation

Residual birefringence in optical fibers causes polarization mode dispersion (PMD). The invention compensates for this by using a polarization mode dispersion compensator and a polarimeter. The PMD compensator has a variable PMD that may be controlled. The output of the PMD compensator is monitored by a polarimeter. By dithering the wavelength of the optical signal, the polarimeter may provide an accurate measure of the PMD. A controller uses this measurement to control the PMD compensator. The PMD compensating scheme may also be incorporated in a wavelength division multiplexed system with each channel having its own PMD compensator. In addition, a control method may control any polarization mode dispersion compensator based on feedback from a polarimeter to reduce the PMD of the input signal. Instead of using a polarimeter, a Q detector may be used to monitor the output of the PMD compensator. The Q detector provides a measurement of the edge sharpness and, thereby, a measure of the PMD. The controller may use the Q value to control the PMD compensator.

Polarization mode dispersion compensating apparatus, system, and method

A three stage optical amplifier is disclosed having a substantially flat gain profile. The amplifier includes a variable optical attenuator coupled between second and third stages of the amplifier and a dispersion compensating element. The attenuation of the optical attenuator is adjusted in accordance with the loss across dispersion compensating element and the optical power input to the amplifier to thereby obtain a substantially flattened gain profile. An offset value can also be used to refine the variable optical attenuator control and minimize nonflatness. The first and second stages are preferably pumped to provide high gain and a low noise figure and the third stage is preferably pumped to provide a high optical conversion efficiency. In an additional example, received optical powers associated with each of the channels in a WDM system are monitored and the attenuators within each amplifier in the system are controlled so that the received powers are substantially equal.

Three-stage optical amplifier having flat spectral gain

A technique in accordance with the present invention provides a systematic approach to find a sub-optimum channel plan with reasonable computational time. In each step, this technique allocates channels to minimize the FWM crosstalk in terms of fiber characteristics, while selecting as many channels as possible to increase the bandwidth efficiency.

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Laurel, MD, United States of America

Michael George Taylor