A Lateral MOS-Capacitor Enabled ITO Mach-Zehnder Modulator for Beam Steering

TL;DR

This paper demonstrates a novel ITO-based Mach-Zehnder interferometer with a lateral MOS phase shifter in silicon photonics, enabling efficient beam steering for applications like LiDAR and holography.

Contribution

Introduction of a lateral MOS configuration in ITO Mach-Zehnder modulators for improved electro-optic performance in integrated photonics.

Findings

Efficient phase modulation with VπL = 63 V·μm.

High-performance optical phased array with narrow beam and side lobe suppression.

Potential for nanosecond beam steering in various optical systems.

Abstract

Here, we experimentally demonstrate an Indium Tin Oxide (ITO) Mach-Zehnder interferometer heterogeneously integrated in silicon photonics. The phase shifter section is realized in a novel lateral MOS configuration, which, due to favorable electrostatic overlap, leads to efficient modulation (V{\pi}L = 63 Vum). This is achieved by (i) selecting a strong index changing material (ITO) and (ii) improving the field overlap as verified by the electrostatic field lines. Furthermore, we show that this platform serves as a building block in an endfire silicon photonics optical phased array (OPA) with a half-wavelength pitch within the waveguides with anticipated performance, including narrow main beam lobe (<3{\deg}) and >10 dB suppression of the side lobes, while electrostatically steering the emission profile up to plus/minus 80{\deg}, and if further engineered, can lead not only towards nanosecond-fast beam steering capabilities in LiDAR systems but also in holographic display, free-space optical communications, and optical switches.