Low-power thermo-optic silicon modulator for large-scale photonic integrated systems.

Abstract

Silicon platform enables the monolithic realization of large-scale photonic integrated systems. Many emerging applications facilitated by silicon photonics such as optical biosensing, optical neurostimulation, optical phased arrays, holographic displays, 3D cameras, optical machine learning, and optical quantum information processing systems require the integration of a large number of optical phase modulators with modest modulation speed. Classical optical modulators are not suitable for such large-scale integration because of their inability to provide low optical loss, compact size, high efficiency, and wide optical bandwidth, all at the same time. We report a thermo-optic silicon modulator realized in a 0.0023-mm2 silicon footprint of a commercial foundry silicon photonics process. The optical modulator consumes 2.56 mW for 180° phase modulation over 100-nm optical bandwidth while achieving 1.23-dB optical loss without air-gap trench or silicon undercut post-processing. Geometrical design optimization, at the core of this demonstration, is applicable to the realization of compact thermo-optic devices for large-scale programmable photonic integrated systems, with a potential to reduce power consumption roughly by an order of magnitude without sacrificing scalability and optical modulation bandwidth.