Wall-coated cells for Rb atomic clocks: Study of the ripening process by double-resonance spectroscopy

We present a study of our in-house made tetracontane wall-coated ⁸⁷Rb vapour cells for rubidium atomic clock applications. Evolution of the double-resonance (DR) signal during the so-called ripening process of these cells is measured and interpreted. Intrinsic properties of the coated cells post ripening are presented. Intrinsic linewidths below 70 Hz, and moderate temperature coefficients (1.5 × 10^-10 /K) are promising cell properties in view of highly compact and miniature atomic clocks.