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The key operating parameters of a grazing-incidence optical parametric oscillator (GIOPO) based on b-BaB 2 O 4 pumped by the third harmonic of a Nd:YAG laser are studied. The bandwidth of the GIOPO is investigated as a function of both the pump-laser bandwidth and the incident angle on the diffraction grating. The efficiency of the device is investigated by measurement of both the depletion of the pump laser and the output of the GIOPO. The results indicate a strong dependence of the bandwidth of the GIOPO on the bandwidth of the pump laser. A qualitative evaluation is given to explain this dependence.

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The performance of collinear and noncollinear pulsed barium borate optical parametric oscillators with third-harmonic Nd:YAG pumping is analyzed. The effects of tangential phase matching and pump Poynting vector walk-off compensation are shown to enhance noncollinear operation. However, we show that these effects are mutually exclusive for a typeI beta-barium borate optical parametric oscillator and furthermore that tangential phase matching is dominant. The selection of a collinear or a noncollinear configuration is determined by pump divergence and spot size as well as by crystal aperture. With a pump divergence of 4mrad, noncollinear operation is optimal. The highest slope efficiency, 37%, and the lowest threshold, 5mJ, are obtained with nearly perfect tangential phase matching. For a pump divergence of less than 2mrad and a similar spot size, collinear operation gives the lowest threshold, 3.2mJ, and the highest slope efficiency, 33%.