Energy Transfer Dye Laser Study of Influence of Various Coumarin Dyes on the Laser Performance of Rh590(Cl) Dye

Abstract

Different coumarin dyes(C440, C460, C480, C485, C500 and C540A) are mixed with Rh590(Cl) in ethanol. The effect of coumarin dyes and their concentration on the laser gain properties and photostabilities of Rh590(Cl) is studied and discussed by investigating the gain characteristics at various concentrations and pump powers of N2–laser. It is found that for C480 and C540A dyes at optimized concentration, most of the absorbed pump power is transferred to Rh590(Cl) as a useful pump power. The gain characteristics of Rh590(Cl)are found to be changed due to change in the fluorescence lifetime. The mechanism responsible for the improvement in the laser performance and gain characteristics of Rh590(Cl) resulted from the energy transfer from these coumarin dyes. This improvement in the laser efficiency of Rh590(Cl) varied sharply depending upon the kind of coumarin dye. The theoretical calculations are also done to find the total transfer efficiency at various donor concentrations to identify the appropriate energy transfer mechanism responsible for gain enhancement in Rh590(Cl) dye. These calculations take into account the contribution due to both radiative and non radiative energy transfer. In these dye mixtures the energy transfer excitation was found to overcome the inner filter effect and other losses such as photoquenching. The concentration dependence of peak gain and the lasing wavelengths of ETDL have been studied. The experimental results indicate that the dominant mechanism responsible for the efficient excitation transfer in these mixtures is of non radiative nature due to long range dipole-dipole interaction. A broader tunable range is also provided by energy transfer.