Effect of the pump depletion itself on the quasi-phase-matching for second-harmonic generation

Abstract

The so-called quasi-phase-matching (QPM) for second-harmonic generation (SHG) considering depletion of the pumping light power is amended. The conversion efficiency of SHG and the optimum domain width are discussed. The applicable scope of undepleted pump approximation (UPA) is estimated and a relative tolerance showing the difference in the SHG between the UPA and the pump depletion is solely determined by the SHG conversion efficiency. A model is fitted using the relevant data, and the results reveal that the conversion efficiency of SHG can be conveniently and easily assessed under the given conditions of pump intensity, the nonlinear media and the number of domains. The optimum domain widths deviate from the coherence length lc = π/Δk. The deviation increases with the pump intensity, but there is little impact on SHG due to system variations in crystal length.