Dependence of the random laser behavior on the concentrations of dye and scatterers

Abstract

We have studied stimulated emission in a random laser based on rhodamine 6G dye and TiO2 nanoparticles. At both small and large concentrations of nanoparticles, the minimum threshold was found at ultra-high concentrations of dye, 20 g L−1. With the increase in concentration of TiO2 nanoparticles, the threshold reaches its maximum at the transition from a weak-scattering regime to a strong-scattering regime, when the transport mean free path lt is approximately equal to the absorption length la. At the same value of lt, the random laser emission qualitatively changes its behavior. The experimental results are in good agreement with the predictions of a heuristic model.

Analytical solution for the Lévy-like steady-state distribution of intensities in random lasers

“…br PACS number(s): 42.55.Zz, 42.25.Dd, 05.40.Fb nonresonant regim e. T his feature has been first dem onstrated in Ref. [22], and was also recently corroborated in three-photon pum ped Z nO -based RLs in two different designs, namely, a ZnO -on-Si thin film [23] and a subm icron scale ZnO pow der [24], A nother im portant characteristic o f RLs is the threshold dependence on scatter concentration [25].…”

Three-photon excitation of an upconversion random laser in ZnO-on-Si nanostructured films

“…The threshold calculated using the "FWHM" criterion is ≈42 μJ. This difference can be explained as a consequence of very different values for the absorption length (l a ) and the transport mean free path (l t ) as shown in [38].…”

A Random Laser Based on Hybrid Fluorescent Dye and Diamond Nanoneedles

“…The linewidth of the lasing peak was ≈9 nm, which was six times narrower than the linewidth of the amplified spontaneous emission peak below the threshold. A threshold behavior was observed at ≈0.64 mJ as the integrated intensity increases nonlinearly with the pump power . The lasing threshold is clearly confirmed as a “kink” in the log–log plot (Figure c).…”