Influence of rotational diffusion of molecules on the characteristics of stimulated emission of dye solutions

A numerical calculation is reported of the characteristics of stimulated emission from solutions of complex molecules subjected to pulsed excitation. An allowance is made for the Brownian rotation of molecules. The calculation is carried out using the transfer equations for the energy density in the resonator and the kinetic equations for the populations of the electronic states without allowance for the induced absorption. The limits of validity of the adopted model are considered. It is shown that an increase in the rate of Brownian rotation of molecules increases the threshold and reduces the lasing energy, and it also smoothes out the structure of the lasing pulses. The characteristic features of the rotational depolarization of laser radiation are discussed.