Numerical analysis of broadband second harmonic generation using TIR-QPM in a parabolic profiled isotropic semiconductor slab

We report second harmonic generation (SHG) with a flat wide bandwidth accompanied by good conversion efficiency in an isotropic semiconductor slab with a parabolic upper profile. The concept of SHG conversion stands on the principle of total internal reflection quasi-phase matching (TIR-QPM). A simulation has been performed using GaAs as the non-linear material, in the fundamental wavelength range of 6.8–10.8 μm, considering ppp polarization configuration. Optimized simulation results, after considering reflection and absorption losses, show a flatter bandwidth of 642 nm in a 36 mm slab in comparison to a dipped 3 dB bandwidth of 770 nm in an elliptically profiled isotropic slab as well as a steeper bandwidth of 187 nm in a tapered isotropic slab. The present simulation shows an acceptable conversion efficiency of 1.105%.