Investigation of the laserlike behavior of polymeric scattering gain mediaunder subpicosecond laser excitation

The narrowing effects of scatterers on the lifetime and the spectral width of the laser-induced fluorescence of organic dyes hosted in poly(methyl met hacrylate) polymer sheets were studied. The excitation source was a distrib uted-feedback dye laser emitting 0.5-ps pulses at 496 nm. Spectral and temp oral features were recorded simultaneously on a spectrograph-streak-camera detection system. The results were then compared with those obtained from d ye solutions in methanol that were recorded in previous studies. The effect s of the different host environments on the fluorescence characteristics of the dye were thus investigated. These effects are currently studied when t he dye is inserted into human tissue in an attempt to boost tumor detection and photodynamic-therapy efficiency. Some initial results are presented. ( C) 1999 Optical Society of America.