Spectral Selectivity of Photonic Crystal Infrared Photodetectors

In this paper, we present the simulation results on the absorption modification in photonic crystal (PC) structures. For one-dimensional (1D) PC, using transfer matrix method (TMM), we obtained enhanced absorption in both defectfree and defect based PC structures. High absorption (>60%) and small bandwidth (< 0.1 λ0) at defect level were observed with optimal absorption layers of 10-15 for structures with single defect. We also present the modified infrared absorption in two-dimensional photonic crystal slabs (2D PCS), based on the three-dimensional finitedifference time-domain method (3D FDTD). The normalized absorption power spectral density in single defect based 2D PCS structures increased by a factor of 18 at the PC defect mode level. This enhancement factor is largely dependent upon the spectral overlap between the absorption material and the defect mode cavity. Complete absorption suppression within the photonic bandgap region was also observed in defect-free cavities, and in single defect cavities when the absorption spectral band has no overlap with the photonic bandgap.