Pulse-periodic tunable (0.63–3.4 μ) optical parametric oscillator for nonlinear spectroscopy

A description is given of a singly resonant optical parametric oscillator utilizing a lithium iodate crystal and operating in the infrared range. The pump radiation was the second harmonic of a single-mode pulse YAG laser with a periodically operated amplifier. The use of this pumping system made it possible to tune continuously the output radiation in the 0.63–3.4 μ range and to obtain an output power of ~100 kW per pulse with a line width 2–10 cm^–1. Fabry-Perot frequency selectors placed inside the resonator of the parametric oscillator made it possible to reduce the line width to < 0.1 cm^–1 throughout the tuning range. This parametric oscillator system was used to study the dispersion of the nonlinear third-order susceptibility of chloroform.