Stable 85Rb micro vapour cells: fabrication based on anodic bonding and application in chip-scale atomic clocks

We describe the microfabrication of Rb-85 vapour cells using a glass silicon anodic bonding technique and in situ chemical reaction between rubidium chloride and barium azide to produce Rb Under controlled conditions, the pure metallic Rb drops and buffer gases were obtained in the cells with a few mm(3) internal volumes during the cell sealing process At an ambient temperature of 90 degrees C the optical absorption resonance of Rb-85 D1 transition with proper broadening and the corresponding coherent population trapping (CPT) resonance, with a signal contrast of 1 5% and linewidth of about 1 7 kHz, have been detected The sealing quality and the stability of the cells have also been demonstrated experimentally by using the helium leaking detection and the after-9 month optoelectronics measurement which shows a similar CPT signal as its original status In addition, the physics package of chip-scale atomic clock (CSAC) based on the cell was realized The measured frequency stability of the physics package can reach to 2 1 x 10(-10) at one second when the cell was heated to 100 degrees C which proved that the cell has the quality to be used in portable and battery-operated devices