Epitaxial neodymium-doped sapphire films, a new active medium for waveguide lasers, R. Kumaran, S. Webster, S. Penson, W. Li, T. Tiedje, P. Wei, F. Schiettekatte, Optics Lett. 34, 3358-3360 (2009)

Epitaxial films of neodymium-doped sapphire have been grown by molecular beam epitaxy on R-, A-, and M-plane sapphire substrates. The emission spectrum features sharp lines consistent with single-site doping of the Nd(3+) ion into the host crystal. This material is believed to be a nonequilibrium phase, inaccessible by conventional high-temperature growth methods. Neodymium-doped sapphire has a promising lasing line at 1096 nm with an emission cross section of 11.9x10¹⁹cm², similar to the 1064 nm line of Nd:YVO(4).