Abstract

Future optical-communication systems will benefit from the optical frequency-multiplexing technique, which exploits the full bandwidth of the optical fiber. A basic component of such a system is an optical heterodyne receiver, which combines extremely high frequency selectivity with high optical sensitivity. A monolithic integration can improve not only compactness and reliability but also the performance at high-speed operation. In this paper we present the monolithic integration of an optical 3-dB coupler with a pair of photodiodes. This photonic integrated circuit (PIC) operates as a complete balanced-mixer detector for a 1.55-μm wavelength and can be used as a building block in a heterodyne receiver. In comparison to integrated receivers presented to date,^1,2 our PIC demonstrates a very high signal bandwidth, which is essential for future high-speed OFDM systems.

© 1995 Optical Society of America