Spatial structure of dye-doped polymer nanoparticle laser media

The spatial structure of dye-doped polymer-nanoparticle gain media, reported to generate spatially homogeneous single-transverse-mode laser beams, has been examined by electron microscopy in the nanometer scale. It is found that the distribution of the silica nanoparticles in the laser dye-doped polymer is fairly uniform. There is some aggregation of silica particles into loose nanoclusters. However, the nanocluster dimensions are smaller than those necessary to satisfy the conditions for internal interference in the visible spectrum. This explains the absence of macroscopic spatial inhomogeneities in the emission laser beams.