DESIGN AND ANALYSIS OF THE X-WAVE-GUIDE OPTICAL SWITCH IN A MESFET GEOMETRY

Theoretical analysis of the change in refractive index, in the channel of a GaAs MESFET (metal oxide semiconductor field effect transistor) structure, has been presented for the first time. The analysis shows great potential applications, to use the MESFET geometries, in the design of optical modulators, and switches for monolithic integration. A X-waveguide-type optical switch has been incorporated into the MESFET geometry, and its switching characteristics have been studied by using the beam propagation method. No switching region has been deliberately built into the waveguide. Instead, the gate and drain voltages of the MESFET automatically form and control the switching region. A light wave propagated through a waveguide is reflected by the depletion edge due to the large change of refractive index. An extinction ratio better than 8.75 dB has been obtained at the gate voltage of 7 V.