Towards low loss non-volatile phase change materials in mid index waveguides

TL;DR

This paper investigates low-loss phase change materials Sb2S3 and Sb2Se3 integrated into silicon nitride photonic circuits, demonstrating their potential for low-loss, non-volatile optical switching in mid-infrared waveguides.

Contribution

It introduces and evaluates two new low-loss phase change materials, Sb2S3 and Sb2Se3, for use in integrated photonic devices, showing their low insertion loss and effective index contrast.

Findings

Insertion loss below 0.04 dB/um for Sb2S3

Insertion loss below 0.09 dB/um for Sb2Se3

Effective refractive index contrast measured at different wavelengths

Abstract

Photonic integrated circuits currently use platform intrinsic thermo-optic and electro-optic effects to implement dynamic functions such as switching, modulation and other processing. Currently, there is a drive to implement field programmable photonic circuits, a need which is only magnified by new neuromorphic and quantum computing applications. The most promising non-volatile photonic components employ phase change materials such as GST and GSST, which had their origin in electronic memory. However, in the optical domain, these compounds introduce significant losses potentially preventing a large number of applications. Here, we evaluate the use of two newly introduced low loss phase change materials, Sb2S3 and Sb2Se3, on a silicon nitride photonic platform. We focus the study on Mach-Zehnder interferometers that operate at the O and C bands to demonstrate the performance of the system. Our measurements show an insertion loss below 0.04 dB/um for Sb2S3 and lower than 0.09 dB/um for Sb2Se3 cladded devices for both amorphous and crystalline phases. The effective refractive index contrast for Sb2S3 on SiNx was measured to be 0.05 at 1310 nm and 0.02 at 1550 nm, whereas for Sb2Se3, it was 0.03 at 1310 nm and 0.05 at 1550 nm highlighting the performance of the integrated device.