An experiment of optical heterodyne transmission with polarization modulation at 140 Mbit/s bitrate and 1550 nm wavelength

An experimental coherent system with polarization shift keying (POLSK) modulation and heterodyne (square-Iaw) detection on two orthogonal channels has been demonstrated. The transmission tests have been performed at bit rates from 64 Mb/s to 140 Mb/ s, using two distributed feedback lasers at 1.548 μm as source and local oscillator. The system theory is reviewed to illustrate the equivalence with frequency shift keying on the basis of the error probability function. The optical setup is accurately described, in particular the polarization modulator and the heterodyne receiver configuration. Preliminary experiments show an excellent phase noise subtractivity of the receiver and an output eye-diagram which compares favorably with the simulated one