Rotation of a KH₂PO₄ crystal and its effect on the second-harmonic generation of a high-average-power laser beam

The rotation of a K H ₂ P O ₄ (KDP) crystal in an optomechanical system and its effect on the second-harmonic generation (SHG) efficiency of a high-average-power laser beam are studied. A method is proposed to study the rotation of the KDP crystal caused by the gravity-induced distortion of the optomechanical system and its effect on the SHG efficiency, as well as the formation mechanism of the rotation and the effects of structural parameters of the optomechanical system. The results indicate that the rotation of the KDP crystal causes a decrease in the SHG efficiency, and appropriate structural parameters of the optomechanical system are beneficial to decrease the rotation and increase the SHG efficiency.