Laser emissions from disodium fluorescein-doped poly(vinyl alcohol) films

Superradiant-mode laser emissions were obtained from disodium fluorescein ( DF)-doped poly(vinyl alcohol) (PVA) films which had been dip-coated on a mi croscope glass slide. When the film was transversely pumped using a nitroge n laser, superradiant emission was trapped and propagated in the supporting glass slide which acted as a waveguide. The trapped light underwent multip le internal reflections before it exited at both ends of the slide, produci ng a lasing effect. The laser beam profile varied with the edge condition o f the glass slide; a circular beam was obtained with a frosted edge. An out put conversion efficiency of 22% was obtained for a fresh sample while its lasing output energy at a localized excitation position, or operating lifet ime, decreased at a rate of 0.015% per shot of nitrogen laser. Despite the decrease in output energy, the laser peak wavelength of DF was largely unch anged.