Microfabricated vapor cells filled with a cesium dispensing paste for miniature atomic clocks

A method for filling alkali vapor cells with cesium from a dispensing paste is proposed and its compliance with miniature atomic clock applications is evaluated. The paste is an organic-inorganic composition of cesium molybdate, zirconium-aluminum powder, and a hybrid organic-inorganic binder. It is compatible with collective deposition processes such as micro-drop dispensing, which can be done under ambient atmosphere at the wafer-level. After deposition and sealing by anodic bonding, cesium is released from the consolidated paste through local heating with a high power laser. Linear absorption signals have been observed over one year in several cells, showing a stable atomic density. For further validation of this technology for clock applications, one cell has been implemented in a coherent population trapping clock setup to monitor its frequency stability. A fractional frequency aging rate around -4.4 x 10(-12) per day has been observed, which is compliant with a clock frequency instability below 1 x 10(-11) at one day integration time. This filling method can drastically reduce the cost and the complexity of alkali vapor cell fabrication. Published by AIP Publishing.