An efficient THz source with a tuning range of 71.1-2830 /spl mu/m (0.106-4.22 THz) based on frequency mixing in a GaP crystal

The authors present the result of efficiently producing the THz radiations by using collinear phase-matched difference-frequency generation (DFG) in a GaP crystal. The authors have extended the THz output wavelengths to as long as 2830 mum. In addition, the peak power has reached 15.6 W. Since GaP is a cubic crystal, there is no need to rotate this in order to tune the output wavelength in a wide range. The two mixing beams used for the DFG experiments were an idler beam (0.73-1.8 mum) from a BBO-based master oscillator/power oscillator pumped by a frequency-tripled Nd:YAG laser and a Nd:YAG laser beam (1.064 mum) with the pulse width of 10 ns. A GaP crystal with a dimension of 19.9 mm along [001] and 25 mm times 25 mm for the cross section was used