Thermal-Optic Switch by Total Internal Reflection of Micromachined Silicon Prism

This paper reports the conceptual design and experimental demonstration of an optical switch that utilizes the thermo-optic effect (TOE) and total internal reflection (TIR) of a micromachined silicon prism. The key idea is to change the refractive index of the prism via TOE to switch the light from the transmission state to the TIR state. The structure is fabricated by microelectromechanical systems (MEMS) technology on a silicon-on-insulator wafer. It requires a temperature change of 69 K to switch from the transmission to the reflection states, which measure isolations of 15.6 and 40.1 dB, respectively. This design is advantageous over the other waveguide switches and photonic crystal devices in the aspects of the absence of beam splitting, tremendously enhanced sensitivity of switching to small change in refractive index, high compactness, and potentially fast and low power switching.