pulse-injection-seeded nanosecond optical parametric oscillator

We measured 90% pump depletion in a singly resonant image-rotating nanosecond optical parametric oscillator that was pulse-injection seeded by a self-generated signal pulse. The oscillator was pumped by an 8 ns duration single-frequency 532 nm pulse from an injection-seeded Q-switched Nd:YAG laser and resonated an 803 nm signal. The pump and pulsed-seed beams had flat-topped spatial fluence profiles with diameters of approximately 6 mm, giving a cavity Fresnel number at 803 nm approaching 400. The beam cleanup effects of the image-rotating cavity produce a far-field signal spatial fluence profile with approximately 60% of its energy falling within the diffraction-limited spot size. © 2006 Optical Society of America OCIS codes: 190.4970, 190.4410, 140.4780.