Progress in the development of an optical frequency standard at 192.6 THz based on a two-photon transition of rubidium atoms at Laval University
Christine Latrasse, M. Poulin, Driss Touahri +2 more
We have developed frequency standards at 192.6 THz (1556.2 nm) based on the two-photon transitions in rubidium at 385.2 THz (778.1 nm). These standards use a high power DFB laser at 1556.2 nm and second harmonic generation (SHG) in a periodically poled lithium niobate (PPLN) crystal. The linewidth of the DFB is reduced to the kHz level using optical feedback from a confocal cavity. The SH light is used to injection-lock a 778.1 nm laser diode which allows to observe and lock the 1556.2 nm laser to the (5S/sub 1/2/,F/sub g/=2-5D/sub 5/2/,F/sub e/=4) two-photon transition /sup 87/Rb. Allan variance measurements between identical standards show a beat stability 2.5/spl times/10/sup -13///spl tau//sup 1/2/ for observation times between 100 ms and 10 s and a level of 5.8/spl times/10/sup -14/ for 100 s is obtained. These standards have been moved recently to the National Research Council, Ottawa, Canada in order to measure their absolute frequency.
Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS)•Jan 22, 2003•1 citation