20 Gbit/s Optical Transmission Systems with Monolithic IC Technologies

Abstract

Rapid progress in multimedia communication requires large capacity optical transmission lines over 10 Gbit/s. One of the candidates considered for forthcoming high speed transmission systems is 20 Gb/s optical IM-DD transmission system. There have been several reports about IM-DD optical transmission experiments at 20 Gbit/s (1, 2, 3, 4). Monolithic integrated circuits are indispensable to turn such high speed optical transmission systems into practical application. The performance of various monolithic ICs for optical communications is summarized in Fig. 1. Si ICs are very attractive for realizing the high speed IM-DD systems up to 20 Gbit/s, because of their high uniformity and yield (5, 6, 7). The Si bipolar transistors, however, are not suited to fabricate circuits with high output voltage swing such as modulator driver, because of their breakdown voltage limitation. The compound devices, such as GaAs-HBTs, GaAs-MESFET and heterojunction FETs, have high cut-off frequency over 100 GHz (8, 9), so they are very effective to achieve the high speed ICs operating over 20 Gbit/s. They also have the advantage of utilizing microwave circuit technologies, which make it possible to design high frequency narrowband circuit, such as a clock amplifier at over 20 GHz.