MULTILEVEL POLARIZATION SHIFT KEYING - OPTIMUM RECEIVER STRUCTURE ANDPERFORMANCE EVALUATION

Multilevel digital coherent optical modulation schemes based on the st ate of polarization of a fully polarized lightwave are proposed and an alyzed. Based on the complete statistical characterization of the Stok es parameters, extracted through appropriate signal processing in the presence of shot and additive gaussian noise, the optimum maximum like lihood receiver operating symbol by symbol is derived. The exact perfo rmance in terms of the average symbol error probability is found. Opti mum constellations for the case of equipower 4, 8, 16 and 32 signals a re found on the basis of the minimization of the error probability for a given average power. Their performance turns out to be promising as compared to other standard modulation techniques. The spectral analys is of polarization modulated signals is presented. A new receiver stru cture, which solves the problem of the excess penalties incurred in th e presence of channel dichroism, is proposed and analyzed.