Laser frequency stabilization using fm optical pumping spectroscopy

We show a novel method for laser stabilization using FM optical pumping spectroscopy with counter-propagating beams. This method uses a variation of FM saturation spectroscopy, where the saturation and probe beam are replaced by two laser beams with different frequencies. In this scheme, the probe beam is produced by a laser stabilized with FM saturation spectroscopy, whereas the saturation beam (pumping beam) is generated by a second laser, without any modulation. The spectra thus obtained lack the crossover lines and Doppler well that are characteristic of conventional saturation spectroscopy. We show the results in frequency stabilization of a laser diode using this technique and Cs-133, finding relative stability values of the same order of magnitude as other traditional stabilization techniques.