Energy and spectral characteristics of a parametric generator based on a nonlinear ZnGeP{sub 2} crystal pumped by a Ho : YAG laser

We have experimentally realised the average generation power of a parametric generator based on a ZnGeP{sub 2} single crystal, which constituted ∼1.5 W at an efficiency of ∼28.6 % in the wavelength range of 3.5 – 4.8 μm with an average pump radiation power of ∼5.5 W and its energy density of ∼ 0.47 J cm{sup −2}. It is shown that there are threshold conditions for the average pump power, providing the realisation of parametric generation. In this case, an increase in the generation efficiency with an increase in the energy density of pump radiation to ∼ 0.4 J cm{sup −2} is observed; with its further increase, the output power increases due to a decrease in the parametric generation threshold. Parametric generators (PGs) based on ZnGeP{sub 2} single crystals with such characteristics are promising for solving many applied problems, including generation of terahertz radiation when nonlinear crystals are pumped by radiation from these PGs at difference frequency. (paper)