Numerical study on slow-light effects in an ultra-compact grating-based Fabry–Perot cavity

In this paper, we propose a slow-light element based on a grating-based Fabry–Perot cavity (GBFPC). Using three-dimensional finite-difference time-domain simulation, the slow-light properties that depend on its structural parameters are systematically investigated. A slow-light effect with the maximum group index about 14.6 and the slow-light bandwidth about 874 GHz at near 1550 nm wavelength is achieved. Moreover, we find that changing of the GBFPC’s structural parameters, such as bus waveguide width W, grating period p, and period number N, has greater impact on its slow-light properties than its other parameters. This study helps lay a solid foundation for designing excellent slow-light elements based on a Fabry–Perot cavity.