Optical delay lines in topological microring resonator array

Abstract

We use a periodic microring resonator array (MRRA) to realize photonic topological insulator (PTI). By tuning the coupling of resonators, two topological edge states can be observed in different bands in the dispersive band, normalized transmission spectrum and light field distribution. From the dispersion band structure, we calculate the group velocity, group velocity dispersion, normalized delay bandwidth product and other delay properties. It is demonstrated that optical delay lines (ODLs) in topological MRRA not only can obtain a comparable delay times, but also show a flatter transmission spectrum and more stable delay time, compared with the traditional coupled resonator optical waveguide. Our work may provide a theoretical reference for the topological ODLs with robust transmission.