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) L G10 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 T E M 00 Gaussian profile. The experimental demonstration of the theoretical approach has been performed using the L G10 and T E M 00 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.