Intensity detection noise in pulsed vapor cell frequency standards

Laser intensity noise is currently recognized as one of the main factors limiting the short-term stability of vapor-cell clocks. In this paper, we propose a signal theory approach to estimate the contribution of the laser intensity fluctuations to the short-term stability of vapor-cell clocks working in pulsed regime. Specifically, given a laser intensity noise spectrum, an analytical expression is derived to evaluate its impact onto the clock Allan deviation. The theory has been tested for two intensity noise spectra of interest in clock applications: white frequency noise and flicker noise. The predicted results turn out in good agreement with experiments performed with a prototype of pulsed optically pumped (POP) Rb cell clock and can be extended to other compact clocks.