Fluorescence and Bleaching of Organic Dyes for a Passive Q-Switch Laser

Abstract

An experimental study has been conducted of the bleaching of several families of saturable dyes by ruby‐laser radiation. Measurements have been made of the time‐resolved fluorescent spectra and the time‐resolved transmission spectra of various dye–solvent combinations. These measurements have been used to determine the decay channels, the lifetimes, and the temperature dependence of the lifetimes involved in the desaturation of the dyes. The results show that the phthalocyanine dyes bleach over the whole red absorption band, while polymethine‐type dyes bleach only over a narrow band around the exciting wavelength. The importance of absorption from the triplet state as a limiting mechanism in the saturation of a dye is also demonstrated by these experiments.