Simulation of the temperature-beam coupling in frequency doubling of BBO crystals

Abstract

First, a frequency doubling model with 4-dimensional temperature-beam coupling was proposed in this paper on the assumption of an infinite transverse crystal section. The frequency doubling process, by using analytical formula and iterative method, was simulated in the BBO crystal pumped by a laser with watt-level power. The amplitudes and conversion efficiencies of the fundamental, and harmonic beams and temperature distributions were obtained, together with the time evolution of temperature field and beam intensities. The influence of the pumping power and crystal length on the conversion efficiency and temperature field was analyzed secondly. The results finally showed that the temperature distribution has great influence on the conversion efficiency and beam quality. A compensation for the phase mismatch induced by temperature can well improve the reduction of conversion efficiency induced by the thermal effect, which thus should be considered in practice.

Simulation of thermo-optic coupling in the thermally anisotropic gallium selenide crystal for second harmonic generation

“…Assuming that the fundamental and harmonic beams travel along the z axis (figure 1), its form is E 1,2 (x, y, z) = A 1,2 exp(ik 1,2 z), where E 1,2 , A 1,2 and k 1,2 are respectively the electric fields, their amplitudes and wave vectors. Via a scaling of relevant parameters and using equation (1a), known coupling equations [4,12] are turned [6] into:…”

“…Seidel and Mann demonstrated a numerical model including thermo-optic coupling with an iteration method [5], where the transverse dimension is simplified to maintain a cylindrical symmetry. Huang et al proposed a model to estimate thermo-optic coupling in beta-barium borate (BBO) crystal with 3-d spatial consideration, which, however, omitted transverse boundaries [6]. At the same time, Sabaeian et al presented a similar model to treat the temperature evolution in potassium titanyl phosphate (KTP) crystal for type II SHG, with the first and second transverse boundary conditions [7].…”