Multiband, continuously tunable filter in 100-300 GHz range using a two-layer cavity of perforated, all-dielectric metasurfaces

A single-layer, all-dielectric, miniaturized metasurface useful for the terahertz (THz) range is designed and analyzed. The metasurface has an overall size of 6 mm x 6 mm x 0.79 mm with a 10 x 10 array of holes on it. This frequency selective surface (FSS) exhibits dual passbands at 164.20 and 257.56 GHz, with a wide stop band between them. Computational analysis is carried out for both infinite and finite structure to show the reliability of the design. Using two such identical surfaces, the analysis is extended for multi-frequency transmission. By cascading two identical layers, with a variable but small air gap between them, continuous tunability and high passband selectivity over 100-300 GHz is possible. The continuous tunability is achieved using the Fabry-Perot cavity mechanism, where the cascading distance plays a critical role in achieving tunability. To verify the robustness of the two-layer FSS structure, in-plane rotation of the first FSS with respect to the other, and in-plane shift of second FSS with respect to the first along one direction is also analyzed. The structure showed invariance towards both these changes, and hence provides freedom from misalignment errors.

Automated summary

A single-layer, all-dielectric, miniaturized metasurface for the terahertz range is designed and analyzed. It exhibits dual passbands at 164.20 and 257.56 GHz, with a wide stop band between them. By cascading two identical layers with a variably small air gap, continuous tunability and high passband selectivity over 100-300 GHz is achieved. The structure also shows invariance towards in-plane rotation and shift, providing freedom from misalignment errors.