Compact, tunable polarization transforming reflector for quasi-optical devices used in terahertz science.

We describe the design, fabrication, and characterization of a compact polarization transforming reflector (PTR). The device can be easily tuned over a broad frequency range, has very little insertion losses, and can easily be integrated into quasi-optical systems that are based on a half-cube design. By varying the distance between the wire grid and a flat mirror, the polarization state of an arbitrary polarized Gaussian incident beam can be set to an output Gaussian beam in either linear or circular polarization. In addition, by varying the orientation of the wire grid, the PTR can be used as a universal polarizer, a property that has not been discussed or demonstrated in the literature. The ability to control the electric field polarization at Terahertz (THz) frequencies is essential for many applications, such as THz spectroscopy and high-field electron paramagnetic resonance spectroscopy.