An Efficient, Fast‐Responding, Low‐Loss Thermo‐Optic Phase Shifter Based on a Hydrogen‐Doped Indium Oxide Microheater

Abstract

AbstractThermo‐optic (TO) phase shifters are very fundamental units in large‐scale active silicon photonic integrated circuits (PICs). However, due to the limitation of microheater materials with a trade‐off between heating efficiency and absorption loss, designs reported so far typically suffer from slow response time, high power consumption, low yields, and so on. Here, an energy‐efficient, fast‐responding, low‐loss TO phase shifter is demonstrated by introducing hydrogen‐doped indium oxide (IHO) films as the microheater, and the optimized electron concentration with enhanced mobility endows the IHO with high conductivity as well as high near‐infrared (NIR) transparency, which allow it to directly contact the silicon waveguide without any insulating layer for efficient tuning and fast response. The TO phase shifter achieves a sub‐microsecond response time (970 ns/980 ns) with a π phase shift power consumption of 9.6 mW, and the insertion loss introduced by the IHO microheater is ≈0.5 dB. The proposed IHO‐based microheaters with compatible processing technology illustrate the great potential of such material in the application of large‐scale silicon PICs.