Spectral characteristics of broad band-rejection filter based on Bragg grating, one-dimensional photonic crystal, and subwavelength grating waveguide

Abstract

Abstract In this paper, the spectral characteristics of broad band-rejection filters composed of Bragg grating (BG), one-dimensional Photonic crystal (1D PC) and subwavelength grating (SWG) waveguide is discussed. The numerical study is conducted via 3D-finite element method (3D-FEM). To provide a fair comparison of the bandwidth and extinction ratio (ER) of the filter designs based on three different approaches, the waveguide width, height, length, grating period are kept constant. For the filter performance analysis, the grating period is fixed at 400 nm while the remaining geometric parameters are optimized to obtain the maximum ER and bandwidth. The maximum ER of >24 dB is obtained for all the three filter models having a footprint of 13.85 × 1 μm2 while the band-rejection bandwidth of BG, 1D PC and SWG waveguide is 158 nm, 432 nm and 295 nm, respectively. We believe that the study presented in this work will assist the researchers to choose the appropriate filter configuration to obtain maximum filter performance.