We demonstrate the first electronically switchable Bragg structure for THz frequencies. The structure works as stop-band filter and as mirror. It exhibits the 60 GHz broad stop-band around 300 GHz which can be removed by reorienting liquid crystal molecules in an external electric field. Our first proof-of-principle experiments agree very well with transfer matrix calculations.

Liquid crystals represent a very interesting material system but their properties in the THz range have not been extensively investigated yet. In this paper we investigate the THz properties of four liquid crystals from the CB family (5CB, 6CB, 7CB and 8CB). In addition to absolute refractive indices and absorption coefficients we present accurate birefringence measurements for different electric fields and temperatures.

Liquid crystals (LC) represent a very interesting material system but their properties in the THz range have not been extensively investigated yet. We examine the properties of 5CB, 6CB, 7CB and 8CB over a broad temperature and electric field range. Moreover, an electrically tunable THz phase-shifter is demonstrated.I.