Pulsed optical pumping in a Rb vapor cell using a compact magnetron-type microwave cavity

A compact magnetron-type microwave cavity has previously been developed for a high performance Rb atomic clock based on conventional continuous-wave double-resonance (DR) interrogation. This magnetron-type cavity shows a homogenous microwave field distribution while having a cavity volume of only 35 cm³. So it is interesting for realizing a high performance Rb cell clock based on pulsed optical pumping (POP) technique with a reduced physics package size. In this proceeding we report on the evaluation of pulsed optical pumping with our magnetron-type cavity. Using the pulsed technique and optical detection, high-contrast Ramsey fringes were observed. The central fringe of the Ramsey signal has a linewidth of 160 Hz and contrast of 35%. Under these conditions, the shot-noise limit is estimated at a level around 2×10^-14 τ^-1/2 which shows the great potential of a POP clock based on the compact magnetron-type cavity. The Rabi oscillation result also indicates an acceptable uniform field distribution inside the cavity for a high-performance POP clock. Some optimizations of pumping and detection power for improving the contrast are also presented.