Terahertz narrow-band filter based on rectangle photonic crystal

A terahertz filter with a channel drop cavity and a resonant reflection cavity in a two-dimensional photonic crystal is theoretically proposed. The channel drop cavity is used to trap photons at resonant frequency from the bus waveguide through coupling and emit them to a drop waveguide, while the resonant reflection cavity is used to realize wavelength selective reflection feedback in the bus waveguide. The transmission properties of the terahertz filter are simulated using the finite element method. It is found that a peak with the central frequency of 1.12 THz is existed in the transmission spectrum. The full width at half maximum of the passband is only 5 GHz, and the peak drop efficiency is up to 94.8%.