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.