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Q: Quantenoptik
Q 121: Laser II
Q 121.3: Talk
Monday, March 4, 2002, 17:00–17:15, HS 22/B01
Efficient generation of blue light at 469 nm by frequency doubling of a diode-pumped Nd:YAG laser — •Ralf Koch, Stefan Bjurshagen, and David Evekull — Acreo AB, Electrum 236, SE-164 40 Kista, Sweden
The 4F3/2 → 4I9/2 transition at 946 nm (R1 → Z5) in Nd:YAG attracts particular attention as it allows generation of blue light by frequency doubling. However, efficient lasing on this transition at 946 nm is considerably more difficult to achieve than on the 1064 nm line. The problems with the 946 nm transition are its quasi-three-level nature and a very small stimulated-emission cross section [1]. There is another, even weaker transition at 938.5 nm (R2 → Z5) [2].
We report efficient operation of a diode-end-pumped Nd:YAG laser at 938.5 nm. The 938.5 nm and the 946 nm lines both have the same lower laser level. To suppress lasing at the 946 nm line, we have used frequency selection provided by an uncoated quartz etalon, inserted into the laser resonator.
We obtained a continuous wave output power of 3.9 W. We believe that this represents the highest cw power demonstrated for a Nd:YAG laser at 938.5 nm. Single-pass frequency doubling in periodically poled KTP delivered a power of 88 mW at 469 nm. By intracavity frequency doubling we achieved an output of 200 mW in the blue.
[1] T.Y. Fan and R.L. Byer, IEEE J. Quantum Electron. QE-23 (1987) 605-612
[2] M. Birnbaum, A.W. Tucker, and P.J. Pomphrey, IEEE J.Quantum Electron. QE-8 (1972) 501