Demonstration of a Reliable High-power 780 nm Laser for use with the RACE, CLASS, and QuITE Missions

Development of a space qualifiable high-power laser suitable for performing laser cooling experiments has been identified as a "tall tent-pole" item for the Rubidium Atomic Clock Experiment (RACE) mission and for subsequent LCAP missions such as CLASS and QuITE. Researchers at JPL recently demonstrated the generation of over 1 watt of tunable cw light at 780 nm, by single pass frequency doubling the output of an erbium-doped fiber amplifier in a cascade of two periodically poled lithium niobate (PPLN) crystals. Over 500 mW is generated in a single crystal, corresponding to an absolute second harmonic generation (SHG) efficiency of 10%. The team believes this to be the highest cw SHG efficiency reported for bulk PPLN crystals in the ~1.5mm wavelength range, and the efficiency is comparable to the best cw results reported at any wavelength, with the appropriate wavelength scaling. To demonstrate its utility for atomic physics experiments, the laser system was employed in a sophisticated laser cooling experiment in which a 2-D magneto-optical trap (MOT) is used to load an ultra-high vacuum MOT. In terms of both loading rates and achievable atom temperatures, the performance is comparable to a Ti:Sapphire based system. This work was performed in the Quantum Sciences and Technologies group at JPL by Rob Thompson, Meirong Tu, David Aveline, Nathan Lundblad, and Lute Maleki.