Low loss switchable topological photonic crystal enabled by submicron-scale patterning and phase-change of Sb2Se3

TL;DR

This paper demonstrates a low-loss, reconfigurable topological photonic crystal by integrating ultra-low-loss Sb2Se3 phase-change material, enabling high-Q topological phase transitions without optical absorption issues.

Contribution

It introduces submicron-scale patterning of Sb2Se3 on a silicon photonic crystal, achieving reconfigurable topological phases with minimal optical loss, unlike previous GST-based approaches.

Findings

Achieved high Q-factor (~10^3) in reconfigurable PTIs

Demonstrated topological phase transition via phase change of Sb2Se3

Resolved absorption-loss bottleneck in tunable topological photonics

Abstract

Photonic topological insulators (PTIs) offer robust platforms for light manipulation, but reconfigurable control of their topological properties without degrading performance remains a major challenge. While phase-change materials (PCMs) provide large refractive index modulation, widely used materials such as Ge2Sb2Te5 (GST) have been successfully deployed in commercial applications including optical data storage. However, they exhibit significant optical absorption in their crystalline state, which poses a challenge for transmissive photonic devices such as PTIs where high transparency is essential. Here, we overcome this fundamental limitation by integrating the ultra-low-loss PCM antimony triselenide (Sb2Se3) onto a silicon-based 2D PTI. We achieve submicron-scale selective patterning of Sb2Se3 on a photonic crystal for the first time, and demonstrate a topological phase transition induced by the material phase change. Owing to the transparency of Sb2Se3 in both its amorphous and crystalline states, a high Q-factor on the order of 10^3 is preserved-representing nearly an order-of-magnitude improvement over previous GST-based devices. This work resolves the absorption-loss bottleneck in reconfigurable PTIs and paves the way for practical, low-loss, tunable topological photonic devices.