Flexible Bragg reflectors for the terahertz regime composed of polymeric compounds

Terahertz technology holds a huge potential for a variety of applications in science and the industry, but still suffers from the lack of widely available system components. Not only active but also passive components like reflectors and filters are needed to advance the maturity of terahertz technology in general. Here, we present high quality, flexible, low-cost terahertz Bragg reflectors and filters based on polymeric compounds. The compounding technology allows to custom tailor dielectric properties as desired for the mirror design, namely a high index of refraction and low absorption at the center frequency of the reflector or filter. Two different base materials are evaluated: poly(propylene) (PP) and poly(vinylidene fluoride co- hexafluoropropylene) (PVDF). In both cases, rutile titania (TiO₂) serves as high refractive index additive. The frequency dependent reflection coefficient of a nine layer PVDF and a five layer PP- based mirror are measured for a set of angles, both in s- and p-polarization, using a fiber coupled terahertz time domain spectrometer. Transfer matrix simulations are in good agreement with the experimental data.