On-Chip Non-Volatile Reconfigurable Phase Change Topological Photonics

Programmable on-chip terahertz (THz) topological photonic devices are poised to address the rising need for high-capacity data systems, offering broad bandwidth, minimal loss, and reconfigurability. However, current THz topological chips rely on volatile tuning mechanisms that require continuous power to function. Here, a nonvolatile, programmable THz topological silicon chip is demonstrated that integrates a waveguide-cavity coupled system with phase-change material, Ge₂Sb₂Te₅ (GST), enabling persistent and efficient functionality without constant power input. Through precise tuning of the intermediate phase states of GST between amorphous and crystalline forms, a stable, non-volatile reconfiguration of the topological cavity is achieved, enabling transitions across over-coupling, critical coupling, and under-coupling states. Multi-level modulation of resonance transmission with a modulation depth of 70 dB is demonstrated, enabling precise control over the onset and disappearance of resonance modes and dynamic tuning of critical coupling states. The THz topological chip facilitates phototunable, volatile modulation across nonvolatile configurations, allowing controlled resetting of the coupling states of the cavity. Here, the first nonvolatile, programmable terahertz topological integrated chip is demonstrated, offering flexible control over resonance modes. This advancement significantly paves the way for integrating phase change materials into silicon topological chips for programmable photonic devices, including interconnects, modulators, and logic circuits.