An Optical Coherent Transmission System Based on Polarization Modulation and Heterodyne Detection at 155 Mbit/s Bitrate and 1.55 μ.m Wavelength

The digital modulation schemes of optical coherent transmissions which show the highest efficiency are based on angle modulation techniques, such as frequency and phase shift keying (FSK, PSK). Their optimum performance are due to the advantage of a complete exploitation of the source emission, since sending an equal amount of energy for each bit, the maximum transmitted power remains unchanged at any time.