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Measured extinction spectrum (curve a) from the silver suspension, showing a peak at . Curve b is the theoretical spectrum calculated from Mie theory for a diameter silver sphere, which peaks at . The width of the experimental spectrum originates from the size and shape dispersion in the sample. The inset shows the scanning electron microscope image of the polydisperse silver nanoparticles.
Random lasing from silver nanoparticles in rhodamine 6G at a MFP . (a) The broadband fluorescence spectrum from the system pumped at below the lasing threshold. (b) The narrowband high-intensity emission spectrum with a linewidth of at a pump fluence, . (c) Spectrum of pure dye pumped at .
Variation of the emission linewidth with pump fluence . The silver-scatterer-based random laser at (open triangle) performs on par with a dielectric-scatterer () based random laser (dotted line, closed circle) at .
Dependence of the threshold energy fluence (open circles) and linewidth narrowing factor (filled circles) on scattering strength . Random lasing is observed over a wide optimal range of scattering strengths, centered around the crossover between subdiffusive and diffusive photon transport regimes. (Dotted vertical lines indicate the approximate transition from subdiffusive to diffusive scattering at .)
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