Fabrication and spectroscopy of Cs vapor cells with buffer gas for miniature atomic clock

In this communication we discuss the fabrication and spectroscopic characterization of original micro-fabricated Cs cells filled with buffer gas in view of applications in miniature atomic clocks. The influence of several experimental parameters on CPT resonances in such micro cells is studied. We observed a quadratic temperature dependence of the clock frequency in a micro-fabricated cell filled with Cs and pure Ne buffer gas. This results in a low temperature coefficient around the inversion temperature, and relaxes the stability requirements on the cell temperature and should improve the clock´s long term stability. The possibility to achieve such low temperature coefficient using a single type of buffer gas can noticeably simplify the technique of the cell production. Indeed, the control of the buffer-gas represents a difficult challenge in micro-fabricated cells production. Finally we report on preliminary short term clock stability measurements. A stability of 5x10-10 τ-1/2 @ 1s is obtained. This value is in good agreement with the signal-tonoise stability prediction but remains to be improved.