Abstract

Room temperature, tunable cw operation of a Cr:Forsterite laser has been obtained by using Nd:YAG laser pumping. A 10 mm long, 3 mm diameter, AR-coated Cr:Forsterite rod (Mediscience Technology, Inc.) was longitudinally pumped in a 10.4 cm long hemispherical cavity consisting of a flat total reflector and a 10 cm radius output coupler. The Nd:YAG pump was focused through the rear mirror and onto the rod face by using a 10 cm focal length lens. A thermoelectric cooler was used to actively cool the rod. In fixed wavelength operation with a 1.1 %T output coupler, the laser threshold was 1W, the slope efficiency was 11.4%, and an output power 190 mW was obtained with 2.5 W of absorbed pump power. Modulating the pump with a 10% duty cycle increased the slope efficiency to 14.9% and output power to 250 mW. Lasing was centered at 1.24 μm with a line width of 4.8 nm. By using a single plate biréfringent tuner, the laser was tuned from 1.19 to 1.33 μm with a pump power of 2.5 W and a single 1.1 %T output coupler. A maximum output power of 125 mW was obtained at 1.22 μm, and the linewidth was reduced to 1.3 nm. To our knowledge, the tuning range of 134 nm is the largest yet obtained at room temperature.

© 1992 Optical Society of America