Frequency doubling of 1.053 μm radiation in KTP

Abstract

Abstract Thermal-optical modeling of a 1.053 μ m → 0.526 μ m potassium titanyl phosphate (KTP) frequency doubler was performed in support of the Los Alamos National Laboratory free-electron laser (FEL) program. Radiation at the doubled frequency is used to excite electron emission from the FEL photoinjector. The fully coupled thermal-optical behavior of the frequency doubler is described by curves of conversion efficiency and plots of the KTP steady-state temperature profile. It is found that thermally induced phase mismatches reduce the conversion efficiency, but can be partially compensated with intentional mismatches introduced by means of a small rotation of the crystal away form the nominal phase matching direction. The computed thermal gradients are used to assess the risk of crystal damage. A general calculational procedure for modeling thermal-optical interactions in the nonlinear three-wave mixing process is presented.