Angle tunable terahertz band notch filter with single-band and dual-band switching characteristics based on metallic strip structures

An angle tunable terahertz band notch filter based on the metamaterial structure of dual metallic strips is designed, fabricated and characterized in this paper. The proposed device consists of a surface metal bar structure with a glass substrate. The structure of the device has been optimized by studying the resonance characteristics of different lengths of metal bars and their combinations. Varying the angle between the metal bars and the terahertz polarization allows for an overall adjustment of the resonant strength at both resonance dips. As the angle increases from 0 to 90 degrees, the transmission at 0.81 THz increases from −8.24 dB to −1.44 dB and that at 1.37 THz increases from −9.61 dB to −2.11 dB. In addition, by varying the rotation angle between the metal bars inside a unit cell, the resonant strength at the corresponding frequency can be adjusted, enabling the filtering mode transition from a single to a dual resonant state. Our proposed dual metallic strips THz filter possesses several desirable merits such as simple structure, ease of fabrication and easy tenability. These characteristics make it a good candidate for a variety of applications in terahertz filters, modulators or switching devices with multiple operating bands.