Thermo-optic phase shifter based on hydrogen-doped indium oxide microheater

TL;DR

This paper introduces a hydrogen-doped indium oxide microheater for thermo-optic phase shifters, achieving fast response, low power consumption, and low insertion loss, suitable for large-scale silicon photonic integrated circuits.

Contribution

It demonstrates a novel IHO microheater with high conductivity and transparency, enabling efficient, fast, and low-loss thermo-optic phase shifting without insulating layers.

Findings

Sub-microsecond response time (~970 ns)

Power consumption of 9.6 mW for {b1} phase shift

Insertion loss of approximately 0.5 dB

Abstract

Thermo-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, we demonstrate an energy-efficient, fast-response, and low-loss TO phase shifter by introducing hydrogen-doped indium oxide (IHO) films as microheater, and the optimized electron concentration with enhanced mobility endows the IHO 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 {\pi} 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.