Multiple frequency stabilization of lasers using double saturation spectroscopy

We have developed a method of stabilizing multiple lasers based on double saturation spectroscopy. Compared with other laser-stabilization methods based on conventional saturation spectroscopy, ours provides numerous reference spectra constructed with several velocity groups of atoms. Two independent laser sources can be simultaneously stabilized by using combined optical-pumping processes associated with a single Rb reference. We analyzed the stability of the feedback loop taking the correlation effect of the saturation spectra into consideration. We experimentally demonstrated two stabilized laser sources with a frequency difference of 6,109 MHz in the ⁸⁷Rb D₂ line. The results were in good agreement with theory within errors in measurement.