Two-Photon Absorption of the DCM Molecule under Femtosecond Excitation between 720 and 920 nm

Abstract

Nonlinear absorption of the DCM dye has been investigated by the two-quantum etalon method and the z-scan method with excitation by a tunable femtosecond Ti-sapphire laser (3 W, 140 fs, and 80 MHz). The two-photon absorption (TPA) spectrum of the DCM molecule has been obtained here for the first time between 720 and 920 nm and has been related to the absorption bands under linear excitation. It has been shown that in measurements of nonlinear absorption by the z-scan method the main contribution to changes in the transmittance comes from the triplet − triplet absorption.