Ciena Corporation

Nortel Networks Corporation

Kevin Stuart Farley

Kim Bryon Roberts

Maurice M O'Sullivan

Richard E Epworth

Qunbi Zhuge

Alan Robinson

Edgar Velez

Frederic J Simard

Anant Grewal

Daniel A Watley

Saeid Seydnejad

Francisco Javier Vaquero-Caballero

Kun Han

Aiping Liang

Zhongwei Li

Maurice O'sullivan

A first signal is generated having a first frequency spectrum comprising one or more stopbands in which components of the first signal exhibit attenuated energy relative to an average energy of the first signal. A second signal is generated having a second frequency spectrum comprising non-zero energy at frequencies within the one or more stopbands. A third signal is generated by a crosstalk-inducing subsystem from a combination of the first signal and the second signal. The third signal is detected at a receiver device and an estimate of crosstalk induced by the crosstalk-inducing subsystem is calculated using a measurement of the third signal at the frequencies within the one or more stopbands. According to some examples, the second frequency spectrum comprises a tone within at least one of the stopbands.

Measurement of crosstalk

A digital instruction is generated regarding one or more electrical-to-optical conversion impairments induced at the transmitter of an optical communication system. The digital instruction may be used by the transmitter to reduce the impairments. Alternatively, or additionally, the digital instruction may be used by the receiver of the optical communication system to compensate for the impairments.

Mitigation of electrical-to-optical conversion impairments induced at transmitter

A method of receiving an optical signal through an optical communication system. The optical signal is transmitted by a transmitter of the optical communication system with a predetermined State of Polarization in a succession of signalling intervals. The SoP in each signalling interval is selected to excite two orthogonal eigenvectors of Polarization Mode Dispersion (PMD) of the optical communication system. The SoP in one signalling interval may be different from the SoP in at least one other signalling interval. Modulation of the optical signal is detected in two orthogonal polarization directions. Modulation components associated with one of the two orthogonal eigenvectors are selected and used to recover data.

Polarization mode dispersion (PMD) tolerant optical signaling

In method of controlling an optical amplifier dynamically adapts to both configuration and performance changes of a communications system. An error vector is calculated to indicate a difference between respective detected values and target values of a parameter of a light beam downstream of the optical amplifier. A sensitivity matrix indicative of a sensitivity of the detected parameter value to incremental changes in a control variable of the optical amplifier is calculated. A predicted optimum value of the control variable is then calculated using the error vector and the sensitivity matrix. Calculation of the predicted optimum control variable value can be iterative, with the sensitivity matrix calculated either during each iteration, or at the beginning of each optimization run. As a result, optimization of the amplifier control variables is performed based on a sensitivity matrix that accurately reflects the performance of the amplifier.

Adaptive optical amplifier control

A method of compensating the polarisation mode dispersion (PMD) of an optical transmission path carrying clocked digital data traffic involves modulating the state of polarisation (SOP) of the light launched into the transmission path, and employing consequential frequency components in an electrical signal detected at the far end of the transmission path to regulate the birefringence of a polarisation state controller portion of a birefringent element inserted between the transmission path and the receiver's photodetector. The SOP modulation, when represented on a Poincar&eacute; sphere, has an oscillatory rotational component at a frequency f about a first axis of the sphere and an oscillatory rotational component at a frequency f about a second axis of the sphere that is orthogonal to said first axis, and where f &ne;f , f &ne;2f , and f &ne;2f .

Polarization mode dispersion compensation

A method of measuring the polarization mode dispersion (PMD) of an optical transmission path carrying clocked digital data traffic involves modulating the state of polarization (SOP) of the light launched into the transmission path, and detecting consequential frequency components in an electrical signal detected at the far end of the transmission path. The SOP modulation, when represented on a Poincar&eacute; sphere, has an oscillatory rotational component at a frequency f about a first axis of the sphere and an oscillatory rotational component at a frequency f about a second axis of the sphere that is orthogonal to said first axis, and where f &ne;f , f &ne;2f , and f &ne;2f .

Polarization mode dispersion measurement

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Kevin Stuart Farley