Comparison of Thermo-Optic Phase Shifters in Imec's Silicon Photonics Platform

Abstract

Taking advantage of the high thermo-optic coefficient of silicon is an effectiveway to realize optical phase shifting in silicon photonic circuits. Based on the imec iSiPP200 silicon photonics platform, different types of integrated silicon photonic phase shifters are compared, including doped-silicon side heaters, diode-loaded heaters, doped waveguides, and metal top heaters. The effect of thermal insulation on phase shifter efficiency and bandwidth is discussed for different architectures with and without substrate undercut. By locally removing the silicon substrate underneath the heater, the efficiency of doped-silicon side heaters is improved by a factor of 2.7 for a pi phase shift.