Fourth and Fifth harmonic generation by Total Internal Reflection - quasi phase matching using the light of highly multimodal nonlinear guided wave approach in a parallel slab of Magnesium oxide doped lithium niobate

Highly multimodal nonlinear guided wave approach based on Fourth and Fifth harmonic frequency conversion schemes using Total Internal Reflection Quasi phase matching is analytically described in a parallel slab geometry of magnesium oxide doped lithium niobate crystal. The guided wave optics approach provides more accurate and realistic results in comparison to plane ray optics. Effect of nonlinear law of reflection along with other optical losses like absorption, Goos - H & auml;nchen-shift and reflection has also been taken into consideration while calculating the conversion efficiency. Various parametric changes, like variations in slab length and thickness, have also been studied. This scheme significantly improved the conversion efficiency compared to other approaches (e.g., Cascaded generation, periodic polling) utilized for the fourth-harmonic frequency conversion scheme. The conversion efficiency of 0.15418% and 0.00859%, corresponding to the Fourth and Fifth harmonic wavelength of 550 nm and 588 nm, have been observed in a 5 mm and 5.2 mm long crystal, respectively.