Nonlinear Optical Properties of Rose Bengal Dye in the Near Field of Silver Nanoparticles

We discuss empirical regularities demonstrating the phenomenon of plasmon-exciton interaction in mixtures of Rose Bengal (RB) dye and spherical and pyramidal silver nanoparticles (Ag NPs and Ag NTs). We use the Z-scan technique to study nonlinear optical properties of the RB dye under the action of the second harmonic (532 nm) of 10 ns YAG:Nd3(+) laser pulses. In the case of coincidence of the dye with Ag NTs with the light extinction peak at 550 nm located in the RB luminescence region, we observe the formation of a positive dynamic lens (gamma = 4.0 center dot 10(-13) cm(2)/W). It provides the threshold limit regime to 0.005 mJ that is not characteristic for the dye. The observed effect is due to a change in the dye state population, involved in the formation of a nonlinear optical response due to the metal nanoparticle action as an optical antenna under the resonance conditions of the Ag NTs extinction peak (550 nm) and the RB luminescence (570 nm).