Fourth harmonic generation of Laguerre Gaussian beam in BBO crystal by total internal reflection-quasi phase matching technique

Abstract

This work deals with analytical exploration of a highly multimodal nonlinear guided wave approach based Fourth harmonic frequency conversion scheme of Laguerre Gaussian beam through Total Internal Reflection Quasi phase matching technique. The analysis has been carried out in a rectangular slab geometry of anisotropic crystal made of Beta beryllium borate. Compared to the traditional Gaussian beam-based frequency conversion scheme, the proposed scheme achieves nearly 7 times better efficiency of 4.8% in a 2.6 mm long crystal corresponding to an application wavelength of 266 nm. The optical losses like absorption, GH-shift, reflection, and effect due to nonlinear law of reflection have also been incorporated in the analysis. The impact of various parametric changes like variations in slab length and thickness has also been studied to give a better perspective of the whole analysis.