Preparation and lasing of a novel crystalline T-waveguide structure

Summary form only given. We report on the fabrication of a novel dielectric T-shaped channel waveguide by liquid-phase epitaxy. Two Nd:LiYF/sub 4/ layers were grown on a LiYF/sub 4/ substrate perpendicular to each other forming the letter T in cross section. From the fabrication process, an active layer thickness of approximately 30 /spl mu/m was deduced. The whole structure was overgrown with LiYF/sub 4/. Plane parallel optical grade end faces were prepared by polishing. The LiYF/sub 4/ crystal c-axis was in the plane of the end face parallel to the vertical T-bar. Laser experiments were performed with external plane dielectric mirrors coupled directly to the waveguide end faces. Lasing of the 12.8 mm long waveguide was achieved at 1047 nm under Ti:Al/sub 2/O/sub 3/ longitudinal pumping at 792 nm. Confinement of the laser mode to the T-shaped channel could be demonstrated. However, the maximum output power of 47 mW was achieved at an incident pump power of 600 mW (50% duty cycle) only with the mode located in the vertical bar of the T slightly below the junction. Waveguide losses were estimated to be smaller than 0.8 dB/cm.