Terahertz form birefringence.

We report on one-dimensional photonic crystals designed to exhibit a pronounced form birefringence at terahertz frequencies. The crystals can be used as volumetric quasioptical elements for a broad frequency range. Theoretical simulations of the dielectric parameters of these structures are presented as well as measurement results of a polymeric crystal that exhibit a birefringence of 0.25 at 300 GHz. As a potential application, the device is exemplarily used as terahertz wave plate.