Abstract

Balanced-mixer receivers for optical systems, first proposed by Oliver,¹ have been shown to be useful in suppressing local oscillator (LO) excess intensty noise.² Furthermore, such a receiver requires less local oscillator power than does a conventional single-detector receiver. This latter advantage is particularly important for high-bit-rate optical heterodyne systems, since receiver thermal noise increases rapidly in typical PINFET front ends as the intermediate frequency is increased. Hence, to ensure that LO shot noise dominates thermal noise (as desired for maximum sensitivity), LO power must be increased at high speeds. With the limited ouput power available from present semiconductor lasers, sufficient LO power is difficult to obtain for speeds of Gbit/s and Intermediate frequenices near 2 GHz.

© 1986 Optical Society of America