Efficient Frequency Doubling at 399 nm
  This article describes a high-power and narrow-linewidth laser source at 399 nm useful for cooling and trapping of ytterbium atoms. A continuous-wave titanium-sapphire laser at 798 nm is frequency doubled using a lithium triborate crystal in an enhancement cavity. Up to 1.0 W of light at 399 nm has been obtained from 1.3 W of infrared light, with an efficiency of 80 %   This paper was published in Applied Optics and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/ao/abstract.cfm?uri=ao-53-16-3388. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law. 
Marco Pizzocaro, Davide Calonico, Pablo Cancio Pastor, Jacopo Catani,   Giovanni A. Costanzo, Filippo Levi and Luca Lorini
physics.optics