Temperature-dependent THz properties and emission of organic crystal BNA

As high-average power ultrafast lasers become increasingly available for nonlinear conversion, the temperature dependence of material properties crystals becomes relevant. Here, we present temperature-dependent THz complex refractive index measurements organic crystal BNA over a wide range temperatures from 300 K down to 80 frequencies up 4 first time. Our show that whereas has only minor deviation room values, absorption coefficient decreases at low (−24% K). We additionally compare these with conversion efficiency and spectra observed during generation experiments using same actively cooled in range, an Yb-laser excitation. Surprisingly, damage threshold does not improve significantly upon active cooling, pointing mechanism being responsible damage. However, observe significant increase yield (+23%) lower temperatures, which is most likely due reduced absorption. These findings will be useful future designs pumped organic-crystal based THz-TDS systems.