Abstract
A phase-diversity technique is a viable way to achieve wideband TV program transmission systems with closely-arranged optical signals in broadcasting stations. This report describes the first DQPSK coherent detection using phase diversity. An excellent BER of 10 ^<-11> was achieved with received optical power of -27dBm at 2.97Gbit/s that corresponds to the transmitting rate of two channels of the uncompressed digitalized HDTV signal. Optical intensity modulation with a microwave subcarrier is a key technology that can realize QPSK coherent detection easier than the direct optical phase modulation technology so far proposed.
