Transmittance of CsI, AgCl, KRS-5, and KRS-6 Crystals in the Terahertz Range

Spectral dependences of the transmittance of CsI, AgCl, KRS-5 (TlBr–TlI), and KRS-6 (TlCl–TlBr) single crystals in the infrared (IR) and terahertz (THz) spectral ranges are measured. Spectral dependences of the absorption (attenuation) coefficient of these crystals in the spectral range of 200–3000 μm are calculated. It is found that these crystals are transparent in the millimeter range, which makes it possible to use them in THz devices. It should be noted that, in contrast to the IR spectral range, the optical quality of the surface of crystal samples barely affects the transmittance in the millimeter range.