A frequency-stabilized 556-nm laser is an essential tool for experimental studies associated with <sup>1</sup>S<sub>0</sub>-<sup>3</sup>P<sub>1</sub> intercombination transition of ytterbium (Yb) atoms. A 556-nm laser light using a single-pass second harmonic generation (SHG) is obtained in a periodically poled MgO:LiNbO3 (PPLN) crystal pumped by a fiber laser at 1111.6 nm. A robust frequency stabilization method which facilitates the control of laser frequency with an accuracy better than the natural linewidth (187 kHz) of the intercombination line is developed. The short-term frequency jitter is reduced to less than 100 kHz by locking the laser to a home-made reference cavity. A slow frequency drift is sensed by the 556-nm fluorescence signal of an Yb atomic beam excited by one probe beam and is reduced to less than 50-kHz by a computer-controlled servo system. The laser can be stably locked for more than 5 h. This frequency stabilization method can be extended to other alkaline-earth-like atoms with similar weak intercombination lines.
© 2011 Chinese Optics Letters
(140.7010) Lasers and laser optics : Laser trapping
(300.6400) Spectroscopy : Spectroscopy, molecular beam
(140.3425) Lasers and laser optics : Laser stabilization
(140.3515) Lasers and laser optics : Lasers, frequency doubled
Zhuanxian Xiong, Yun Long, Huixing Xiao, Xi Zhang, Lingxiang He, and Baolong Lv, "A robust method for frequency stabilization of 556-nm laser operating at the intercombination transition of ytterbium," Chin. Opt. Lett. 9, 041406- (2011)