Study on the Critical State of 2-D Resonators Topological Insulator

We analyze the coupling between an adjacent field ring and a coupling ring of the 2-D optical resonator array to obtain a topological edge state. Using the finite-difference time-domain method, the energy band structure, light field distribution, and transmission spectrum are simulated to investigate the optimized coupling parameters under the topological boundary state. When the coupling coefficient is approximately 0.775, the system can form a topological state in the wavelength of 1.55– $1.56~\mu \text{m}$ , while output can maintain a flat spectral response with normalized power above 0.9. The research in this article provides a basis for the potential application of topological edge states of 2-D coupled resonant optical waveguide in the field of photonic communication.