Tunable high-power narrow-spectrum external-cavity diode laser at 675 nm as a pump source for UV generation

High-power narrow-spectrum diode laser systems based on tapered gain media in an external cavity are demonstrated at 675 nm. Two 2mm long amplifiers are used, one with a 500 mu m long ridge-waveguide section (device A), the other with a 750 mu m long ridge-waveguide section (device B). Laser system A based on device A is tunable from 663 to 684nm with output power higher than 0.55W in the tuning range; as high as 1.25W output power is obtained at 675.34 nm. The emission spectral bandwidth is less than 0.05nm throughout the tuning range, and the beam quality factor M-2 is 2.07 at an output power of 1.0 W. Laser system B based on device B is tunable from 666 to 685nm. As high as 1.05W output power is obtained around 675.67 nm. The emission spectral bandwidth is less than 0.07nm throughout the tuning range, and the beam quality factor M-2 is 1.13 at an output power of 0.93W. Laser system B is used as a pump source for the generation of 337.6nm UV light by single-pass frequency doubling in a bismuth triborate (BIBO) crystal. An output power of 109 mu W UV light, corresponding to a conversion efficiency of 0.026% W-1, is attained. (C) 2010 Optical Society of America