Heat coupled Gaussian continuous-wave double-pass type-II second harmonic generation: inclusion of thermally induced phase mismatching and thermal lensing.

A model describing the thermal effects in type II second harmonic generation (SHG) of Gaussian continuous-wave (CW) in a double-pass cavity is presented. The thermally induced phase mismatching (TIPM) along with thermal lensing was included in the classical SHG formalism through the interposing the heat and TIPM equations. To this end, eight equations were coupled together and solved simultaneously to reveal how the SHG is affected in time when heat is generated in the crystal. The model showed an excellent agreement with experimental data [Opt. Laser Tech.34, 333-336 (2002)]. Furthermore, a numerical procedure, which was developed in this work, is introduced for simultaneously solving the SHG, heat, and TIPM equations with home-used computing machines.