Low threshold monocrystalline Nd:(Gd, Lu)2O3 channel waveguide laser.

We report the first waveguide laser based on a rare-earth-doped sesquioxide. A 2 microm thick lattice matched Nd(0.5%):(Gd, Lu)(2)O(3) film with a nearly atomically flat surface has been epitaxially grown on a Y(2)O(3) substrate, using pulsed laser deposition. The film has been structured with reactive ion etching and a rib channel waveguide laser has been realized. Laser radiation at 1075 nm and 1079 nm has been observed under 820-nm pumping. The laser possesses a threshold power of about 0.8 mW and a preliminary slope efficiency of 0.5% versus incident pump power. A maximum output power of 1.8 mW has been obtained for 370 mW incident pump power.