Abstract:

A signal equalizer for compensating impairments of an optical signal received through a link of a high speed optical communications network. At least one set of compensation vectors are computed for compensating at least two distinct types of impairments. A frequency domain processor is coupled to receive respective raw multi-bit in-phase (I) and quadrature (Q) sample streams of each received polarization of the optical signal. The frequency domain processor operates to digitally process the multi-bit sample streams, using the compensation vectors, to generate multi-bit estimates of symbols modulated onto each transmitted polarization of the optical signal. The frequency domain processor exhibits respective different responses to each one of the at least two distinct types of impairments.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

This is the first application filed in respect of the present invention.

TECHNICAL FIELD

The present invention relates to high-speed optical communications networks, and in particular to a signal equalizer in a coherent optical receiver.

BACKGROUND OF THE INVENTION

Optical signals received through conventional optical links are typically distorted by significant amounts of chromatic dispersion (CD) and polarization dependent impairments such as Polarization Mode Dispersion (PMD), polarization angle changes and polarization dependent loss (PDL). Chromatic dispersion (CD) on the order of 30,000 ps/nm, and polarization rotation transients at rates of 105 Hz are commonly encountered. Various methods and systems intended to address some of these limitations are known in the art.

FIG. 1 schematically illustrates a representative coherent optical receiver capable of implementing the methods of Applicant"s co-pending U.S. patent application Ser. No. 11/294,613 filed Dec. 6, 2005 and entitled “Polarization Compensation In A Coherent Opti ...

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