Two-Frequency IR Laser System on the Basis of SHG in the Crystal TnGeP2 For Investigation of the Radation-Substance Interaction

Abstract

The effective frequency conversion of CO 2 laser radiation has a significant practical importance in science and techniques, in particular, in an atmospheric laser remote sensing measurements, isotope separation, and laser-induced fusion. Pulse CO 2 lasers have the advantage of other radiation sources that are as follows: high efficiency, large frequency tunability, wide range in energy and pulse duration, and high mean power in a repetition pulse mode. The second and the fourth harmonic generators of CO 2 laser radiation with a pulse duration ∼100 ns, which are built currently on the basis of CdGeAs2 and ZnGeP2 single crystals, have low efficiency. The last is determined by the pump laser intensity and the nonlinear crystal length. The conversion efficiency is sufficiently limited by the surface damage because of the noticeable radiation absorption on the fundamental and second harmonic frequencies. The threshold energy fluence is weakly depended on the pulse duration in the range 1–100 ns, therefore, the pump peak intensity and as a result, conversion efficiency can be increased with 1 ns laser pulses. This chapter discusses the second harmonic generation (SHG) of nanosecond CO 2 laser pulses in a ZnGeP2 nonlinear crystal.