High-performance laser-pumped rubidium frequency standard for satellite navigation

Presented is a double-resonance continuous-wave laser-pumped rubidium (Rb) atomic clock with a short-term stability of 4×10⁻¹³ τ ^−1/2 for integration times 1 s ≤ τ ≤ 1000 s, and a medium- to long-term stability reaching the 1×10⁻¹⁴ level at 10⁴ s. The clock uses an Rb vapour cell with increased diameter of 25 mm, accommodated inside a newly developed compact magnetron-type microwave cavity. This results in a bigger signal with reduced linewidth, and thus improved short-term stability from a clock with 1 dm³ physics package volume only. The medium- to long-term clock stability is achieved by minimising the effects of light-shift and temperature coefficient on the atoms. Potential applications of the clock are discussed.