Compact and Tunable-Multichannel Terahertz Wave Filter

A compact terahertz tunable multichannel filter based on two cascaded photonic crystal waveguide directional couplers, formed by two closely spaced line defect waveguides in a two-dimensional photonic crystal of silicon rods in the air, is numerically studied using plane wave expansion and finite difference time domain methods. The filtering properties of the present terahertz wave filter, including channel number and frequency, can be tuned by adjusting excitation of external applied magnetic field. The dynamical shift of channels with external applied magnetic field intensity is studied in detail. The transmittances of the present filter are higher than 95% for each terahertz wave frequency with a compact size of 3.8 mm × 10 mm. The designed device can possess both multichannel and tuning features, which could be of technical use in the terahertz wave communications system applications.