Microfabrication of 85Rb vapor cell for chip-scale atomic clocks

We describe the fabrication of Rubidium (Rb) vapor cells using glass-silicon anodic bonding techniques and chemical reaction between rubidium chloride and barium azide. The pure metallic Rb drops and buffer gases were obtained in the cells with few mm³ internal volumes. The optical absorption resonance of ⁸⁵Rb 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 at 90degC.