A decision directed algorithm for adjusting a polarization demultiplexer in a coherent detection optical receiver

摘要

The invention relates to a method for adjusting a polarization demultiplexer (1-4) in a coherent optical receiver. The optical receiver is configured for receiving a polarization division multiplexed phase modulated optical signal, preferably a PDM BPSK signal. Such polarization demultiplexer outputs a first signal component (Y1) and a second signal component (X2). According to the method, for at least one of the signal components, a symbol is estimated in dependency of a non-decided symbol (C1, C2) downstream of the polarization demultiplexer. The estimated symbol is selected from a set of given modulation symbols of the phase modulation scheme, e.g, from two modulation symbols in case of BPSK. Preferably, symbol estimation is performed for both signal components. The polarization demultiplexer is adjusted with the help of the symbol estimation.