We present the development of a 33 W eye-safe OPO utilizing KTA crystals and a ring resonator cavity. A 130 W multi-mode near flat-top diode pumped Nd:YAG laser operating at 100 Hz provides 107 W of pump power to the OPO.

We have constructed and fielded a multi-wavelength injection seeded mid-IR OPO source for DIAL. This OPO system was built for ground based remote sensing measurements of species with both broad (300 cm-1) and narrow absorption bandwidth (0.07 cm-1 FWHM). The OPO utilizes a single frequency tunable diode laser for the injection seeded signal wavelength in the region from 6400 to 6700 cm-1 and an angle phase-matched 5 cm LiNbO3 crystal to provide large tuning excursions on a slow time scale. The pump was a diode pumped Nd:YAG MOPA (9398 cm-1) running at 180 Hz. This pump source was repeatedly injection seeded with a different wavelength on each of three sequential shots forming a set of three pulses having wavelength separations on the order of 0.4 cm-1 at a three color set repetition rate of 60 Hz. This combination of OPO signal and pump source produced a set of three time staggered idler wavelengths separated by 0.4 cm-1 with the center wavelength tunable from 2700 to 3000 cm-1. This OPO system was used in field test experiments to detect the release of chemicals from a standoff distance of 3.3 Km. We present key OPO design criteria, performance data, and numerical simulations that agree with our observation of pump induced spectral impurities in the OPO output.

We have made direct measurements of the thermal dependence of the phase- matching angle (θpm) in lithium triborate (LBO) for Types I and II second-harmonic generation (SHG/2ω I and II) and sum- frequency generation (SFG/3ω I & II) of Nd:YAG laser light (1.064 μm) to wavelengths of 0.532 μm and 0.355 μm, respectively. These measurements were made over a temperature range of 24-50°C using the technique discussed in Ref. 1. To our knowledge, this is the first such measurement for 3ω I at these wavelengths. The results of these measurements are shown in Fig. 1.

The properties for members of a new class of nonlinear optical (NLO) materials which stoichiometrically incorporate organic and inorganic constituents into a single crystalline lattice are reported. Recent results for our synthetic, crystal growth, and optical studies suggest that a number of these relatively transparent ”semiorganic” compounds have significant second and/or third order NLO responses and often display favorable crystal growth morphologies. The prototype material of this class, zinc tris(thiourea) sulfate, or ZTS, has a UV cutoff at about 325 nm, can be readily grown to cm3 sizes, and has been shown to be a highly efficient Type II frequency doubler for 1064 nm Nd:YAG laser radiation. ZTS also possesses a moderate third order nonlinear optical response (ca. 0.1 × CS2) which occurs on at least a picosecond time scale as determined by degenerate four-wave mixing (DFWM) experiments at 532 nm. Refractive index, second harmonic generation, and DFWM data for a number of these new compounds are presented.