title: High-efficiency mid-infrared ZnGeP2 optical parametric oscillator directly pumped by a lamp-pumped, Q-switched CrTmHo:YAG laser.
abstract: We report a singly resonant optical parametric oscillator (SRO) based on a ZnGeP(2) crystal directly pumped by a lamp-pumped Q-switched CrTmHo:YAG laser. The IR was tunable from 4.7 to 7.8 microm via crystal angle tuning. A maximum optical to optical efficiency of 56% was obtained from the pump (2.09 microm) to total IR at a pump energy of 6.5 mJ. The corresponding idler energy was 1.45 mJ. The SRO was measured to have a slope efficiency of 64% and a threshold of 1 mJ. The spatial beam quality of the idler, characterized by the M(2) parameter, was 1.38 when the SRO was pumped at 2.5 times threshold. These results show that ZnGeP(2) optical parametric oscillators directly pumped by a CrTmHo:YAG laser can be operated efficiently, while maintaining good IR beam quality.
authors.affiliation: Laser Physics and Nonlinear Optics Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands. a.f.nieuwenhuis@utwente.nl
authors.forename: A F
authors.initials: AF
authors.lastname: Nieuwenhuis
authors.forename: C J
authors.initials: CJ
authors.lastname: Lee
authors.forename: P J M
authors.initials: PJ
authors.lastname: van der Slot
authors.forename: I D
authors.initials: ID
authors.lastname: Lindsay
authors.forename: P
authors.initials: P
authors.lastname: Gross
authors.forename: K-J
authors.initials: KJ
authors.lastname: Boller