Frequency stabilization of laser diode to the 6S-8S two-photon transitions in cesium atoms in a vapor cell placed in an external cavity

We pursue high frequency stability by using a large number of thermal atoms to investigate a possibility of local oscillators in the optical frequency standards. We frequency stabilize an extended-cavity laser diode to the 6S-8S two-photon transition in cesium atoms. We evaluated the frequency stability to be 4.4×10
^-14
at an averaging time of τ = 16 s. We observed that the long term stability was improved by stabilization of the intracavity power.