Mid-infrared ZGP optical parametric oscillator directly pumped by a lamp-pumped, Q-switched Cr,Tm,Ho:YAG laser.

We generate mid-infrared pulsed light tunable between 5.6 &mgr;m and 6.6 &mgr;m using an optical parametric oscillator (OPO) directly pumped by a Cr,Tm,Ho:YAG, Q-switched laser operating at 2.1 &mgr;m. The Holmium laser uses a RTP Q-switch to produce pulses shorter than 100 ns and energies of up to 42 mJ in a single spatial transverse mode at a repetition rate of 5 Hz. To our knowledge this is the first report on a lamp pumped Cr,Tm,Ho:YAG laser using a RTP crystal as an electro-optical Q-switch. The OPO is based on a ZnGeP2 (ZGP) crystal cut for type I phase matching. The singly resonant OPO (SRO) uses a linear cavity consisting of two plane mirrors to minimize the required pump flux to reach threshold. The SRO has a threshold of 2.4 mJ, a maximum idler pulse energy of 3.1 mJ, and is tunable from 5.6 to 6.6 &mgr;m. Operation in this wavelength range, combined with wide tuning and a high pulse energy makes this SRO particularly suitable for tests in the field medical application, e.g., for cutting of soft tissue during surgery or corneal corrections.