Two-stage nanosecond OPO based on LiNbO/sub 3/ and AgGaSe/sub 2/ tunable from 3 /spl mu/m to 6 /spl mu/m

Summary form only given. The long-wavelength limit of high pulse energy optical parametric oscillators (OPOs) based on LiNbO/sub 3/ is limited by crystal transparency to approximately 4 /spl mu/m. For the OPO-operation in spectral ranges above 4 /spl mu/m only a few crystals such as AgGaSe/sub 2/ can be used as second-stage OPO material to extend the tuning further into the mid and far infrared until 14 /spl mu/m. In this paper the tandem OPO was pumped at comparatively high pulse energies (>200 mJ) and simultaneously at high repetition rates of 100 Hz.