Photon statistics of random lasers with resonant feedback

Continuous-wave ultraviolet laser action in strongly scattering Nd-doped alumina

We report electrically pumped, cw laser action near 405 nm from Nd(3+) -doped delta -alumina nanopowders. To our knowledge, this is the first report of stimulated emission from the high-lying F(2) -excited states, achieved through feedback from strong elastic scattering of light over transport path lengths shorter than half a wavelength.

Experimental observation of wave chaos in a conventional optical resonator

We report on an experimental observation of optical wave chaos in a resonator consisting of three standard, high-reflectivity mirrors. The nonseparability of the wave equation necessary for chaos is introduced by violating the paraxial approximation. Until recently progress in optical wave chaos was hampered by the inherent difficulty in realizing suitable microscopic systems; now this novel, macroscopic approach offers complete and easy control and allows unprecedented study of optical wave chaos.

Model for a random laser

The laser action in random media is studied numerically for a planar system of resonant scatterers pumped by an external laser. The eigenmodes of the finite system (quasistates) are "lossy" in the absence of gain because of the leakage of light outside the medium and can be characterized by their decay rates. Lasing occurs when the gain compensates the decay rate of the quasistate with the longest lifetime. The dependence of the lasing threshold on the number of scatterers (size of the system) is found to be I varies with 1/square root of (N), which agrees with recent experiments. We demonstrate that this dependence is strongly related to the fluctuations of quasistate decay rates and discuss the nature of these fluctuations.