Carrier-induced MESFET optical switches for photonic integration

A study is made of the reverse-biased optical switches in a MESFET geometry. Carriers are controlled in the switching region by the gate voltage which can enhance the feasibility of carrier-induced devices in high-speed data communication, optical computing and photonic switching. A waveguide optical switch in a conventional MESFET geometry is proposed which gives an extinction ratio better than 8.75 dB at the operating voltage of 7 V. A further optimised structure to reduce the operating voltage and get better optical characteristics has been designed. Computer analysis of the two-dimensional electrostatic potential and the number of depleted carriers shows that diffused carriers are depleted by applying drain and gate voltages of 2 and -2 V, respectively. The beam propagation method applied to wave propagation shows an on/off ratio better than 15 dB. This considerably improves both electrical and optical characteristics of carrier injection-type optical switches