Abstract

Optical quadrature phase-shift keying (QPSK) with synchronous heterodyne detection is an attractive transmission method because of its high sensitivity and bandwidth efficiency; for a given bit rate, heterodyne QPSK is as sensitive as heterodyne binary PSK but uses only half the bandwidth. Bandwidth efficiency is important in multigigabit systems, because of the limited electrical bandwidth of the receiver, and also in frequency-division multiplexed systems, because it allows more channels to be packed into the limited tuning range of semiconductor lasers.

© 1992 Optical Society of America