Mechanically Tunable Terahertz Circular Polarizer with Versatile Functions

Circular polarizers that selectively transmit only one handedness of circular polarization are useful for imaging and wireless communications. Conventional involve 3D chiral structures, which impose fabrication challenges, while typically introducing chirality within a limited bandwidth. To overcome the limitations associated with conventional non-planar designs, three-layer metasurface-based planar polarizer exhibiting strong broadband is presented here. Its superiority over existing multilayer designs derived from systematic design procedure. Measurement results reveal proposed structure maintains 15-dB extinction ratio 251 to 293 GHz preferred polarization, leading fractional bandwidth 15.4% transmission efficiency above 92.7%. Furthermore, mechanically tunable alter its functionality or operation Specifically, through simply rotating top bottom metallic layer by 90°, can function as transmissive quasi-half-wave plate reverses sense polarization. Moreover, operate at nearby frequency ranges aforementioned functionalities adjusting air gap spacings between layers. Further calculations based on measured each suggest robust deviations in spacings.