Laser action in strongly scattering rare-earth-metal-doped dielectric nanophosphors

We report continuous-wave laser action in two oxide nanopowders doped with Ce 3 + and Pr 3 + ions To our knowledge, these are the first observations of stimulated emission from electrically pumped random media in which scattering and distributed feedback scale lengths are much shorter than a wavelength. The continuous nature of the laser emission in small volumes (on the order of a cubic wavelength) of these low gain systems, and the absence of coherent speckle, provide compelling evidence that these results are mediated by strong Anderson localization of light.