Adaptive PMD equalizer and implementation

摘要

Polarization mode dispersion (PMD) in a dual-pole optical communications network is compensated for using an adaptive PMD equalizer. The PMD equalizer may include a number of substantially identical filter modules that provide partial outputs which may be combined to form a PMD compensated output. A constant modulus algorithm (CMA)-based equalizer may track PMD across both poles and generates an error signal. The CMA-based equalizer includes a filter bank, and uses an update algorithm and tap/output adjustments based on a difference between combined tap energies and an index, and feedback from a forward error correction code frame synchronizer.

主权项

1. An apparatus for adaptive equalization of polarization mode dispersion in an optical signal, comprising:
an input configured to receive multiple input channels corresponding to digitized versions of in-phase and quadrature channels of horizontal and vertical polarity optical signals; a plurality of substantially identical finite impulse response (FIR) filter modules, configured to receive the input channels, receive filter tap error updates, adjust FIR filter tap values based on the received tap error updates, partially filter one or more of the input channels based on the adjusted FIR filter tap values, and output one or more partially filtered input channels; and an error calculation and output generation module configured to receive the partially filtered input channels from the FIR filter modules, combine the partially filtered input channels, output a polarization mode dispersion compensated version of each channel of the digitized optical signal, calculate filter tap error updates, and provide the tap error updates to the plurality of FIR filter modules.