Frequency instability of a miniature optically pumped cesium-beam atomic frequency standard

This paper proposes a miniature optically pumped cesium-beam atomic frequency standard with a volume of 38.4 l and a weight of 28 kg and examines the main factors that affect its signal-to-noise ratio (SNR). Methods to improve the SNR are proposed, which improve the short-term frequency instability: installing a collimator at the exit of the cesium oven, using the beam fluorescence spectrum with the fiber-coupled output to stabilize the laser frequency, and using the 4–5 cycling transition of the cesium D2 line for the atomic detection. We also examine several frequency shifts that affect the long-term frequency instability and detail methods to reduce these shifts. At present, the frequency instability achieved by the Peking University miniature optically pumped cesium-beam frequency standard has reached 3.12×10−12/τ.