Modulation-free sub-Doppler laser frequency stabilization to molecular iodine with a common-path, two-color interferometer.

Recently, a simple common-path, two-color interferometer has been used for Doppler-free saturated dispersion spectroscopy of iodine. We have used such a set-up to stabilize a Nd:YAG laser for the first time, to our knowledge. This method requires only a small number of low-cost optical components compared to frequency modulation techniques.We have measured a root Allan variance of 5 . 10(-12) for 0.2 s, and below 5 . 10 (-11) for integration times up to 300 s.