THz-wave generation and detection from ZnSe crystal induced by a femtosecond laser

We experimentally study THz generation and detection in <111> ZnSe samples using optical rectification and electro-optic sampling. A THz radiation pulse with a width of 113fs (full width at half maximum), results in a wideband THz spectrum near 5.8 THz with a peak signal at 3 THz. We also examine the dependence of the peak THz electric field on optical pump power. The generated peak electric field increase linearly with increasing optical pump power in the ZnSe sample with a clean surface, while for the sample with a carbon-sprinkled surface, the peak field exhibits a slow saturation behavior at powers greater than 250 mW. It seems that the damages surface decreases the optical rectification efficiency.