Lasing of Nd3+ in sapphire

We present a rare-earth-doped sapphire laser. Single-crystalline alpha-Al2O3 films doped with trivalent neodymium have been grown by pulsed laser deposition on undoped sapphire substrates. The Nd3+ doping concentrations of the films have been varied between 0.3 at.% and 2 at.%. Epitaxial growth was proven by structural and optical characterization of the films. The samples exhibit strongly polarization dependent emission transitions from the F-4(3/2) manifold with a fluorescence lifetime of 108 mu s and peak emission cross sections of 1.1 x 10(-18) cm(2) around 1100 nm. Lasing at 1096.5 nm was achieved under Ti: sapphire-pumping in a planar waveguide configuration with a maximum cw output power of 137 mW and a slope efficiency of 7.5% with respect to the incident pump power.