Prototype of an optically pumped cesium beam frequency standard

The prototype of an optically pumped cesium beam frequency standard is composed of three modules: a cesium beam tube, a microwave module, and a laser diode module. In the cesium beam tube, background lights from the windows are reduced. In the microwave module, an automatic level controller is used in order to reduce long-term frequency instabilities caused by the microwave level fluctuation. In the laser diode module, three laser diodes are connected to the cesium beam tube by polarization maintaining fibers and fiber couplers. The short-term frequency stability (two-sample standard deviation), which is estimated from the preliminary experimental results gained from the prototype, is about σ_y(τ)=1×10¹²/√τ