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A High-power Generation in Mid-Infrared Region Based on ZnGeP2 Optical Parametric Oscillation

Zuotao Lei ,  Chong-Qiang Zhu ,  Chao Xu ,  Chunhui Yang 

Harbin Institute of Technology (HIT), No.92, West Da-Zhi Street,Harbin, Heilongjiang, Harbin 150001, China


Zinc germanium phosphide (ZnGeP2, ZGP) is known as one of the most promising materials for nonlinear optical applications due to large nonlinear coefficient and high laser damage threshold. A high optical quality ZnGeP2 single crystal of 50 mm in diameter was successfully grown by the vertical Bridgman technique. The OPO devices were fabricated from ZGP crystal as shown in Fig.1. The absorption coefficient of ZGP OPO devices for o-polarized 2 μm light incidence was significantly reduced to 0.02 cm-1 by thermal annealing and high energy electron irradiation (Fig2.). Moreover, improvement to the polishing of ZGP OPO devices (Fig.3) resulted in an increased laser-induced damage threshold. The value was increased to 2.0 J/cm2 at 2.05 μm and 10 kHz pulse rate frequency. As a result, the maximum output of 20.5 W was obtained by high pulse repetition frequency Ho:YAG laser emitting at 2.09 μm under a pump power of 46W. The corresponding slope efficiency was 68.7% and the conversion efficiency was 44.3% (Fig.4). These results manifested the large crystals with high optical quality are acceptable for the fabrication of the infrared nonlinear OPO devices.


Fig. 1 ZGP-OPO devices


Fig.2 Optical absorption coefficient for o-light


Fig.3 Patterns of roughness and flatness


Fig.4 Output power and slope efficiency


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Related papers

Presentation: Poster at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, Topical Session 6, by Zuotao Lei
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17

Submitted: 2013-04-15 15:18
Revised:   2013-04-15 15:30