Utilization of thermal effects for silicon photonics

Abstract

Thermal effect plays a key role and has been utilized for various photonic devices. For silicon photonics, the thermal effect is usually important because of the large thermo-optical coefficient of silicon material. This paper gives a review for the utilization of thermal effects for silicon photonics. First, the thermal effect is very beneficial to realize energy-efficient silicon photonic devices with tunability/switchability (including switches, variable optical attenuators, etc). Traditionally metal micro-heater sitting on a buried silicon-on-insulator (SOI) nanowire is used to introduce a phase shift for thermal tunability by injecting a electrical current. An effective way to improve the energy-efficiency of thermal tuning is reducing the volume of the optical waveguide as well as the micro-heater. Our recent work on silicon nanophotonic waveguides with novel nano-heaters based on metal wires as well as graphene ribbons will be summarized. Second, the thermal resistance effect of the metal strip on a hybrid plasmonic waveguide structure can be utilized to realize an ultra-small on-chip photodetector available for an ultra-broad band of wavelength, which will also be discussed.