Measurement of excited-state lifetimes of dye molecules using bleaching curves of solutions obtained polarized light

It was established analytically that the results of measurements of the excited-state lifetime of dye molecules using bleaching curves of solutions are influenced by the polarization of the radiation, the anisotropy of the molecular absorption and emission oscillators, and the rotational diffusion time of the molecules. These factors could alter almost twofold the ratio of the molecular lifetime to the observed bleaching intensity of the solution. A 300-ps neodymium laser pulse was used to obtain bleaching curves of various dye solutions and to determine the lifetimes of these dyes in the 2.5–130 ps range. The results of measurements on a solution of dye №15 led to its testing as a passive switch in a neodymium-doped lanthanum beryllate laser and its potential for mode locking of neodymium laser radiation was demonstrated.