Maximum-likelihood optimal-sampling-phase estimation for ultra-high-sensitivity optically preamplified duobinary receivers

This paper describes the demonstration of a novel method for detecting optical duobinary signals. Oversampling in combination with maximum-likelihood estimation-based data processing of the optical-to-electronic converted signal results in a record sensitivity for an optically preamplified receiver. The concept is investigated at 10 Gb/s and allows data recovery at bit-error rates of 1/spl times/10/sup -9/ and 1/spl times/10/sup -3/ with a receiver sensitivity of better than -39.5 dBm and an optical signal-to-noise ratio (OSNR) of only 7.8 dB, respectively.