Stimulated Emission from a TiO₂ Particle-Dispersed Dye Polymer Plane Waveguide

We report the stimulated emission from a dye doped polymer plane waveguide with TiO₂ particles. This waveguide consists of a poly (methylmethacrylate) (PMMA) film containing laser dye DCM as a gain medium. The emission spectrum of the film pumped by the Nd:YAG laser is different from the amplified spontaneous emission of the dye-doped film without particles. It is shown that when the excitation intensity reaches the threshold
9.6μJ, the broad band emission spectrum narrows into multiple separate peaks with central wavelength of 608nm. The linewidth of the sharp peak is 0.5nm. According to our analyses, this phenomenon is due to the multiscattering of the disordered TiO₂ particles inside the gain polymer film.