The effect of RF excitation frequency on the spectrum characteristics of rubidium electrodeless lamp

Rubidium electrodeless lamp is one of the core components of rubidium atomic frequency standard. It plays the role of optical pumping and quantum state preparation, and realizes the particle number inversion between two ground states of rubidium atoms. The RF excitation frequency affects the effective light spectral distribution of rubidium electrodeless lamp, and then determines the pumping efficiency and the limiting frequency stability of rubidium atomic frequency standard. In this paper, the influence of RF excitation frequency on the spectral characteristics of rubidium electrodeless lamp can be optimized based on power compensation. It is found that there is a sensitive dependence between the heating rate and the excitation frequency of the rubidium electrodeless lamp, and the excitation frequency range corresponding to the turning point of the maximum heating rate was given experimentally. When the input power and the bubble wall temperature remain unchanged and the rubidium electrodeless lamp is in the ring-mode state, the spectral characteristics have a depression at the optimum resonance frequency. Therefore, the excitation frequency of the rubidium electrodeless lamp should be properly pulled to 5~9 MHz from the optimum resonant point, which can optimize the spectral characteristics of the rubidium electrodeless lamp and can improve the frequency stability of the rubidium atomic clock.