Gain studies on a uranine-damc dye mixture laser under nitrogen laser pumping

Abstract

The radiative and Forster type of energy transfer processes in a dye mixture laser of 7-diethylamino-4-methyl coumarin (donor) and fluorescein disodium salt (acceptor) under nitrogen laser pumping were investigated. The Forster transfer rate calculated from the absorption and emission spectra of acceptor and donor is 1.3 × 10 11 liter mole −1 sec −1. The gain of acceptor at 550 nm was measured for acceptor concentrations N A from 10 −3 M to 3 × 10 −3 M for a fixed ratio F = 1 of donor to acceptor concentrations at different pump powers. The results agreed with the rate equation model proposed for the dye mixture laser. The radiative rate constant calculated from these results is 3.1 × 10 10 liter mole −1 sec −1. Numerical simulation of the rate equations showed that the acceptor reaches peak emission with a time lag of 3 ns with respect to the donor peak emission for F = 0.998, N A = 10 −5 M. This time lag decreases with increasing N A and becomes zero for N A = 10 −1 M, F = 0.048.