On-chip terahertz tunable topological valley photonic crystals

Abstract

Active on-chip terahertz (THz) topological photonic devices are emerging as promising solutions to meet the growing demand for high-capacity interconnects, offering ultra-broad bandwidth, low loss, and reconfigurability. Nevertheless, most current THz topological chips lack active tuning capabilities that are readily compatible with complementary metal–oxide–semiconductor (CMOS) fabrication processes. In this work, we propose integrating liquid crystals with THz valley photonic crystals (VPCs) to enable active tuning of topological valley kink states. By systematically modulating the surrounding refractive index of the VPC, we dynamically adjust its bandwidth, allowing on-demand control of the transport of topological valley kink states. This advancement marks a significant step toward incorporating CMOS compatible liquid crystal materials into silicon-based topological platforms for programmable photonic applications, such as interconnects, modulators, all-optical circuitry, and logic circuits.