Z-scan model for Laguerre–Gaussian excitation in mode-mismatched thermal lens spectrometry

Abstract

In this work, we have introduced a Z-scan thermal lens (TL) model based on Laguerre–Gaussian (LG) LG10 laser induced excitation in a mode-mismatched dual-beam configuration. The analytical expression of the TL signal and its dependence on sample to detector distance as well as the Z-scan have been derived. The theoretical analysis shows that the phase shift and TL signal are higher than the values obtained using an excitation with the TEM00 Gaussian profile. The experimental demonstration of the theoretical approach has been performed using the LG10 and TEM00 Gaussian beams, respectively. Experimental proofs of the model are presented and found to be in agreement, demonstrating that Laguerre–Gaussian induced excitation is more sensitive than the Gaussian one.