An all-solid-state ultraviolet (UV) laser built by researchers at Mitsubishi Electric (Hyogo, Japan), Osaka University (Osaka, Japan), and KogakuGiken (Kanagawa, Japan) produces 20.5 W of 266-nm light. Consisting of a green-emitting Q-switched diode-pumped Nd:YAG laser and a 15-mm-long cesium lithium borate (CLBO) nonlinear crystal cut at 62° for type-I fourth-harmonic generation, the laser system emits pulsed fourth-harmonic light at a repetition rate of 10 KHz. The green beam has a pulsewidth of 80 ns and a beam quality (M2) of 10 and is 0.3 mm in diameter as it enters the CLBO crystal. The crystal itself has a surface roughness of 0.59 nm rms and is heated to 140°C to prevent hygroscopic deterioration.
The UV power increases as the square of the input green power, while the UV beam quality matches the input M2 of 10. Emitting UV pulses of 46-nm duration, the laser reaches its highest UV output at a green optical input of 105.8 W— a conversion efficiency of 19.4%. Because no saturation or damage has been observed, the researchers believe that increasing the green power will boost the UV output further. Contact Tetsuo Kojima at [email protected].
John Wallace | Senior Technical Editor (1998-2022)
John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.