Compact, Wavelength-selectable, Energy-ratio Variable Nd:YAG Laser at Mid-ultraviolet for Chemical Warfare Agent Detection

We have developed a compact, wavelength-selectable, Q-switched Nd:YAG laser at mid ultraviolet for chemical warfare agent detection. The fundamental wave at 1064 nm is delivered by a pulsed solid state laser incorporating with a square-type Nd:YAG rod in a resonator closed by two crossed Porro prisms for environmental reliability. The output energy at 213 nm (5ω) and 266 nm (4ω) by χ(2) process in the sequentially disposed BBO crystals are measured to be 6.8 mJ and 15.1 mJ, respectively. The output wavelength is selected for 5ω and 4ω by a motorized wavelength switch. The energy ratio of the 5ω to the 4ω is varied from 0.05 to 0.85 by controlling the phase matching temperature of the nonlinear crystal for sum-frequency generation without change of the output pulse parameters.