Frequency Stabilization of a Cesium Faraday Laser With a Double-Layer Vapor Cell as Frequency Reference

We implement a compact optical frequency standard at the wavelength of 852 nm by the modulation transfer spectroscopy (MTS) technique, using a Faraday laser as the local oscillator and a double-layer cesium vapor cell to provide frequency reference. The vacuum space between the two quartz glass layers of the double-layer atomic vapor cell can effectively suppress the temperature fluctuations inside the internal atomic vapor cell. The influences of probe and pump laser powers, modulation frequency, and vapor cell temperature on the slope of the MTS error signal are measured. Utilizing the self-estimation method, we evaluate the frequency stability of the laser system, which can be up to <inline-formula><tex-math notation="LaTeX">${5.8\times 10^{-15}/\sqrt{\tau }}$</tex-math></inline-formula> at short term, dropping to <inline-formula><tex-math notation="LaTeX">${2.0\times 10^{-15}}$</tex-math></inline-formula> at 50 s. This result is obviously superior to that using single-layer vapor cell as the frequency reference. Such an ultrastable laser source can be widely used in the fields of optical metrology and precision measurement.