Multifunctional topological photonic crystal device for multichannel frequency routing and highly sensitive refractive index sensing

Abstract

We propose a novel photonic crystal (PC) structure with C-4 symmetry of the square lattice that utilizes topological edge states (TESs) to achieve multichannel frequency routing and high-sensitivity refractive index (RI) sensing. The proposed system combines trivial and nontrivial unit cells to form a unique lattice arrangement that supports multiple TESs. These states enable the realization of seven distinct output ports, each capable of transmitting a specific frequency, significantly enhancing optical communication systems' bandwidth and data transfer capabilities. This feature makes the proposed PC structure an ideal candidate for multichannel frequency routing applications. Additionally, the structure incorporates a central cavity that exhibits robust light localization, making it highly sensitive to changes in the surrounding medium's refractive index. Simulations demonstrate that the proposed structure can achieve RI sensing sensitivity of up to 721 nm/RIU, coupled with a high-quality factor exceeding 10^5. With its exceptional RI sensing capabilities, the proposed multichannel PC device holds immense potential for various technological advancements in frequency routing.