Berlin 2001 – scientific programme
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Q: Quantenoptik
Q 31: Poster: Laser
Q 31.8: Poster
Friday, April 6, 2001, 12:30–15:00, AT2
High power diode-pumped 946 nm Nd:YAG laser and applications — •Ralf Koch, Filip Öhman, and David Evekull — ACREO AB, Electrum 236, SE-164 40 Kista, Sweden
The 4F3/2 → 4I9/2 transition at 946 nm in Nd:YAG attracts particular attention as it allows generation of blue light by frequency doubling. However, efficient lasing on this transition is considerably more difficult to achieve than on the 1.064 µm line. The problems with the 946 nm transition are its quasi-three-level nature, which results in a significant reabsorption loss, and a very small stimulated emission cross section. This requires tight focusing of the pump beam, which results in strong thermal lensing effects even for moderate pump power levels.
We report efficient room-temperature operation of a compact diode-pumped Nd:YAG laser at 946 nm with more than 5 W continuous wave output power and good beam quality. The laser rod is a transversally water-cooled composite rod with a diameter of 3 mm. Various resonator schemes for coping with the strong thermal lensing effects are discussed.
Activities concerning efficient blue light generation by external frequency doubling in periodically poled KTP are briefly presented.
An additional application of the 946 nm laser is pumping of special single mode Er:Yb:phosphate glass fibers (Kigre, Inc.) with emission at 1.53 µm. The high doping concentration in phosphate glass compared to standard EDFAs enables short devices with only a few cm of active fiber.