Terahertz anisotropic response of additively manufactured one-dimensional photonic crystals.

A polymer-based, one-dimensional photonic crystal exhibiting anisotropic responses was demonstrated in the terahertz frequency range. The photonic crystal was composed of alternating compact and low-density polymethacrylate layers. The low-density layers consisted of sub-wavelength sized columns, which were slanted 45° with respect to the substrate surface normal to achieve form-birefringence. Normal incidence polarized terahertz transmission measurements were carried out for characterization of the fabricated photonic crystals in the range from 82 to 125 GHz. The experimental data revealed a 2 GHz shift in the center frequency of the photonic bandgap as a function of in-plane orientation, well demonstrating the anisotropic behavior of the fabricated crystal. The transmission data were analyzed using stratified optical layer model calculations. A good agreement was found between the relevant model parameters and the corresponding design parameters.