Random Lasing and Reversible Photodegradation in Disperse Orange 11   Dye-Doped PMMA with Dispersed ZrO$_2$ Nanoparticles
  We report the observation of intensity feedback random lasing at 645 nm in Disperse Orange 11 dye-doped PMMA (DO11/PMMA) with dispersed ZrO$_2$ nanoparticles (NPs). The lasing threshold is found to increase with concentration, with the lasing threshold for 0.1 wt\% being $75.8 \pm 9.4$ MW/cm$^2$ and the lasing threshold for 0.5 wt\% being $121.1 \pm 2.1$ MW/cm$^2$, with the linewidth for both concentrations found to be $\approx 10$ nm. We also consider the material's photostability and find that it displays fully reversible photodegradation with the photostability and recovery rate being greater than previously observed for DO11/PMMA without NPs. This enhancement in photostability and recovery rate is found to be explicable by the modified correlated chromophore domain model, with the NPs resulting in the domain free energy advantage increasing from 0.29 eV to 0.41 eV. Additionally, the molecular decay and recovery rates are found to be in agreement with previous measurements of DO11/PMMA [Polymer Chemistry \textbf{4}, 4948 (2013)]. These results present new avenues for the development of robust photodegradation-resistant organic dye-based optical devices. 
Benjamin R. Anderson, Ray Gunawidjaja and Hergen Eilers
physics.optics