Terahertz-pulse generation by photo-ionization of gases under high pressure

Summary form only given. Far-infrared (terahertz) pulses can be generated by photoionization of electrically biased gases with amplified laser pulses. We demonstrate experimentally that the efficiency of this generation process can be significantly increased, when the absolute gas pressure is raised up to 46 bar. The stronger THz output is a result of the extremely high bias fields of up to 200 kV/cm which can be applied under these conditions. The laser pulses are supplied by a CLARK CPA 2001 laser system. They are focused into the gap between two electrodes within a pressure chamber. The THz radiation is detected by an electro-optic detection scheme using a 1-mm ZnTe crystal.