Influence of multi-line CO laser focusing on broadband sum-frequency generation in ZnGeP2

TL;DR

This study investigates how multi-line CO laser focusing enhances broadband sum-frequency generation in ZnGeP2, showing increased efficiency and spectral broadening due to phase-matching and angular dispersion effects.

Contribution

It provides experimental and numerical evidence that multi-line laser focusing improves sum-frequency generation efficiency and spectral bandwidth in nonlinear crystals.

Findings

Maximal conversion efficiency occurs at a focal length 0.4 times that of single-line laser.

Tight focusing broadens the sum-frequency spectrum and increases overall efficiency.

Multi-line laser focusing outperforms single-line focusing in broadband sum-frequency generation.

Abstract

An influence of multi-line CO laser focusing on spectral characteristics of broadband sum-frequency generation in ZnGeP2 nonlinear crystal was experimentally and numerically studied. Maximal frequency conversion was experimentally observed under tight focusing of the multi-line rather than single-line CO laser. The tight focusing resulted in broadening sum-frequency generation spectrum and increasing total, i.e. integrated over the spectrum, frequency conversion efficiency. These effects were due to increasing phase-matching bandwidth and angular dispersion. Maximal conversion efficiency of the multi-line CO laser was numerically demonstrated to take place at the focal length of 0.4 times that for the single-line one.