Random Lasing in Closely Packed Resonant Scatterers
We report experimental and theoretical studies of the random lasing threshold and its fluctuation in an ensemble of highly packed spherical dielectric scatterers. The ratio of the sphere diameter to the lasing wavelength was varied in a wide range, which covered the transition from the weak Rayleigh scattering regime to the strong Mie scattering regime. Experimentally, when the diameters of monodispersed ZnO spherical particles changed from less than 100 to more than 600 nm we observed a drastic decrease of the lasing threshold at small-particle size followed by a plateau at large particle size. We attribute this effect to the particle-size dependence of transport mean free path lt, which was deduced from coherent backscattering measurements. Theoretical calculation of lt reproduced experimental behavior. Using the finite-difference time domain method, we obtained the lasing threshold and its standard deviation as functions of particle size in two-dimensional systems. The results of our numerical simulations are in qualitative agreement with the experimental data.
X. H. Wu et al., "Random Lasing in Closely Packed Resonant Scatterers," Journal of the Optical Society of America B, Optical Society of America, Jan 2004.
The definitive version is available at http://dx.doi.org/10.1364/JOSAB.21.000159
David & Lucile Packard Foundation
National Science Foundation (U.S.)
Keywords and Phrases
Backscattering; Computer simulation; Diffusion; Electromagnetic waves; Green's functions; Photons; Rayleigh scattering; Refractive index; Resonance; Titanium dioxide; Zinc oxide
Article - Journal
© 2004 Optical Society of America, All rights reserved.