PERFORMANCE OF GAAS-MESFET PHOTODETECTORS WITH WIDE DRAIN-TO-GATE DISTANCES IN SUBCARRIER OPTICAL-TRANSMISSION

This paper presents the performance of a proposed GaAs MESFET photodet ector with wide drain-to-gate distances for improving the optical coup ling efficiency in subcarrier optical transmission. Principle and desi gn parameters of the proposed MESFET are described. Link gain, CNR, an d BER, are experimentally investigated as functions of the drain-to-ga te distance. It is experimentally found that the proposed MESFET impro ves the link gain by 8.5 dB compared to the conventional structure at the subcarrier frequency of 140 MHz. Discussions are also included com pared to PIN-PD.