Stimulated emission in dendrimer-doped polymer waveguides

Stimulated emission was studied in dendrimer-doped polymer waveguides. A su pernarrowing laser spectrum was observed without using any resonator mirror s, due to the moderate scattering caused by densely doped dendrimer aggrega tes in a polymer waveguide. At the optimum operation level, the spectral li newidth was found to be 0.55 nm, which was limited by the resolution of the spectrograph used. Weak scattering from the aggregated dendrimers in the h ost polymer matrix with gain was responsible for the photon localization. H owever, in contrast to conventional random lasers with strong scattering, w eak scattering enables the long amplification path through the waveguide pr oducing a directional beam and a supernarrowing spectrum. The dependence of supernarrowing lasing behavior on the density of the scattering moiety was studied by changing the dendrimer doping ratios in the polymer matrix, (C) 2001 Elsevier Science B.V. All rights reserved.