Influence of thermal self-interactions on the continuous generation of the second harmonic

The results are given of an experimental investigation of the influence of thermal self-interactions on the second-harmonic generation in KDP, ADP (90% phase matching), and Ag₃AsS₃ (~22° phase-matching angle) crystals. The cause of the fall of the second-harmonic power was determined. It was found that at pumping powers exceeding a critical value characteristic of a given crystal the conversion efficiency fell because of the induced thermal detuning of the phase matching. The influence of birefringence was also considered.