Analysis of the light shift effect in the 87Rb frequency standard

The ⁸⁷Rb cell frequency standard, optically pumped by a laser diode, is of great interest in the development of high-stability, short-term oscillators. We report the experiments performed on a rubidium-cell prototype aiming to evaluate the transfer of the laser and microwave noise to the hyperfine clock transition via the light-shift effect, which appears to be the main contribution to the observed short- and medium-term instabilities in this kind of a standard. Pulsed optical pumping is also examined in order to strongly reduce the light-shift effect: the experimental results show an improvement in medium term frequency stability