Multi-port programmable silicon photonics using low-loss phase change material Sb$_2$Se$_3$

TL;DR

This paper demonstrates a scalable, low-loss, reconfigurable multi-port silicon photonic device using Sb2Se3 phase change material, enabling efficient optical matrix operations with high accuracy and stability across the C-band.

Contribution

The work introduces a novel silicon photonic platform with integrated Sb2Se3 PCM for multi-port reconfigurable optical matrices, achieving high control accuracy and stability.

Findings

Successfully encoded multi-port operations on silicon photonics using Sb2Se3

Achieved up to 25 matrix element control with 90% accuracy

Devices maintained stable performance across the C-band

Abstract

Reconfigurable photonic devices are rapidly emerging as a cornerstone of next generation optical technologies, with wide ranging applications in quantum simulation, neuromorphic computing, and large-scale photonic processors. A central challenge in this field is identifying an optimal platform to enable compact, efficient, and scalable reconfigurability. Optical phase-change materials (PCMs) offer a compelling solution by enabling non-volatile, reversible tuning of optical properties, compatible with a wide range of device platforms and current CMOS technologies. In particular, antimony tri-selenide ($\text{Sb}_{2}\text{Se}_{3}$) stands out for its ultra low-loss characteristics at telecommunication wavelengths and its reversible switching. In this work, we present an experimental platform capable of encoding multi-port operations onto the transmission matrix of a compact multimode interferometer architecture on standard 220~nm silicon photonics using \textit{in-silico} designed digital patterns. The multi-port devices are clad with a thin film of $\text{Sb}_{2}\text{Se}_{3}$, which can be optically addressed using direct laser writing to provide local perturbations to the refractive index. A range of multi-port geometries from 2$\times$2 up to 5$\times$5 couplers are demonstrated, achieving simultaneous control of up to 25 matrix elements with programming accuracy of 90% relative to simulated patterns. Patterned devices remain stable with consistent optical performance across the C-band wavelengths. Our work establishes a pathway towards the development of large scale PCM-based reconfigurable multi-port devices which will allow implementing matrix operations on three orders of magnitude smaller areas than interferometer meshes.