Two-photon excitation of dyes in a polymer matrix by femtosecond pulses from a Ti:sapphire laser

Two-photon fluorescence was observed for 18 organic dyes in a polymethyl methacrylate (PMMA) matrix excited by a femtosecond Ti:sapphire laser. The product of the cross section for two-photon absorption by the quantum yield of fluorescence (two-photon fluorescence cross section) is estimated by comparing it with fluorescence of Rhodamine 6G in ethanol. Using this parameter, dyes are selected that exhibit the most intense fluorescence in PMMA and their concentrations in PMMA are optimised. Coumarin and rhodamine dyes in polymer matrices are proposed for using as visualisers of femtosecond radiation of a Ti:sapphire laser and as detectors in self-triggering systems.