Phase Diversity Optical Coherent Reception Experiment of DQPSK Signals

Abstract

A phase-diversity technique is a viable technique for transmitting wideband TV programs with closely-arranged optical signals in broadcasting stations. This paper describes DQPSK coherent detection using phase diversity. An excellent BER of 10^-11 was achieved with a received optical power of -27 dBm at 2.97 Gb/s. 2.97 Gb/s corresponds to the transmission rate of two channels of the uncompressed digitalized HDTV signals. Optical intensity modulation with a microwave subcarrier is a key technology that can achieve QPSK coherent detection more easily than the direct optical phase modulation technology proposed so far.