Creating large bandwidth photonic crystal slab waveguide by tailoring the dispersion curve of waveguide mode

摘要

In the photonic crystal (PhC) slab, a waveguide is typically created by introducing a line defect into the perfect periodic lattice, and the waveguide modes will appear within the photonic band gap. An practical waveguide should possess sufficient single-mode bandwidth and display minimal group velocity dispersion within the bandwidth. By adjusting the air holes adjacent to the line defect, the dispersion curves of waveguide modes can be tailored and the requests above are reached. In this way, an air-bridge slab waveguide gets a single-mode bandwidth of 0.025 da, where c is the light speed in vacuum and a is the lattice constant of the photonic crystal. In addition, an SOI (Silicon-on-Insulator) slab waveguide receives a single-mode bandwidth of 0.007 da and a frequency window of 0.003 da with a nearly constant group velocity of 0.082 c.