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Proceedings Paper

Asynchronously sampled blind source separation for coherent optical links
Author(s): Thomas F. Detwiler; Steven M. Searcy; Andrew J. Stark; Stephen E. Ralph; Bert E. Basch
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Paper Abstract

Polarization multiplexing is an integral technique for generating spectrally efficient 100 Gb/s and higher optical links. Post coherent detection DSP-based polarization demultiplexing of QPSK links is commonly performed after timing recovery. We propose and demonstrate a method of asynchronous blind source separation using the constant modulus algorithm (CMA) on the asynchronously sampled signal to initially separate energy from arbitrarily aligned polarization states. This method lends well to implementation as it allows for an open-loop sampling frequency for analog-to-digital conversion at less than twice the symbol rate. We show that the performance of subsequent receiver functions is enhanced by the initial pol demux operation. CMA singularity behavior is avoided through tap settling constraints. The method is applicable to QPSK transmissions and many other modulation formats as well, including general QAM signals, offset-QPSK, and CPM, or a combination thereof. We present the architecture and its performance under several different formats and link conditions. Comparisons of complexity and performance are drawn between the proposed architecture and conventional receivers.

Paper Details

Date Published: 24 January 2011
PDF: 7 pages
Proc. SPIE 7960, Coherent Optical Communication: Components, Subsystems, and Systems, 79600D (24 January 2011); doi: 10.1117/12.874704
Show Author Affiliations
Thomas F. Detwiler, Georgia Institute of Technology (United States)
Steven M. Searcy, Georgia Institute of Technology (United States)
Andrew J. Stark, Georgia Institute of Technology (United States)
Stephen E. Ralph, Georgia Institute of Technology (United States)
Bert E. Basch, Verizon (United States)


Published in SPIE Proceedings Vol. 7960:
Coherent Optical Communication: Components, Subsystems, and Systems
Guifang Li; Dieter Stefan Jäger, Editor(s)

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