Laser Emission of Dye Solutions co-doped with Silver Nanoparticles

In this work dependence of laser emission intensity of liquid solutions of laser dyes Rhodamine 6G, Sulforhodamine 101 and their mixtures doped by silver nanoparticles on the concentration of nano-additives was investigated. It was found that with an increase in the concentration of nanoparticles to a value of 4·10
^-4
mM, the emission energy of nanocomposites increases. It was observed both for nanocomposites containing one dye and for nanocomposites with a mixture of these dyes, between the molecules of which donor-acceptor transfer of excitation energy is possible. It is shown that the increase in emission energy is due to the appearance of strong plasmon-induced optical pumping fields in the vicinity of the nanoparticles. In a nanocomposite with a donor-acceptor mixture of dyes, strong local fields arise not only at the pump radiation frequency but also at the donor emission frequency. This is equivalent to an increase in the efficiency of excitation energy transfer in the donor-acceptor pair of molecules. The effect of an increase in the excitation rate prevails with an increase in the concentration of nanoparticles to a value of 4·10
^-4
mM. With a greater concentration of nanoparticles, the losses due to nanoparticle scattering and absorption become significant, which leads to a decrease in the lasing energy.