CPT-based atomic clock with Rb vapour cell fabricated by direct optical bonding

The work presents a study of CPT-based atomic clocks with miniature rubidium vapour cells fabricated by direct optical bonding (DOB). This MEMS-compatible technology was for the first time used for making cells containing alkali-metal vapour. One of its important advantages is relatively low temperature (e.g. room temperature) required for cell assembly. The work discusses results of spectral measurements of DOB-fabricated cells with a volume of less than 1 cm³ , which provided stability of CPT-based atomic clocks better than 5·10^–11 at 1 second and 5·10^–12 at 24 hours. The obtained results suggest a significant potential of DOB for fabrication of alkali-metal vapour cells for broader application and cost reduction of atomic clocks.