Unlocking silicon's hidden power: on-chip phase transitions enabled by a new nanocavity

Phase-change materials (PCMs) offer powerful tools for optical memories, reconfigurable photonics, and optical neural networks due to reversible optical properties. However, conventional PCMs like GST face challenges in integrated photonics due to poor CMOS compatibility, slow switching speed (ns scale), and high energy consumption (~100 pJ). This project aims to fundamentally challenge the long-held notion that silicon, the cornerstone of integrated photonics, is unsuitable as an optical PCM. We propose a novel approach to realize localized, reversible phase transitions in silicon on a photonic chip by exploiting extreme light confinement in a new nanocavity. If successful, this project will demonstrate for the first time that silicon can reversibly change its state very quickly (sub-ps) and with extremely low energy (sub-pJ). This breakthrough would redefine silicon photonics and open new avenues in optical computing, communications, AI, and quantum technology.