Abstract
This paper reports the proposal, fabrication, and evaluation of Rb vapor cells sealed by two-step bonding for miniature atomic clocks. The proposed fabrication method is separating the light path filled with Alkali atoms and Alkali dispenser’s room at wafer level process. The first fabricated sample is unexpectedly sealed with some air, and the vapor cell is measured the absorption spectra and CPT resonance. The flow solving the problems is indicated, and the vapor cells are fabricated again with the improved process. The FWHM of CPT resonance fits almost the theoretical value in vacuum-sealed samples, which are filled with Rb atoms carried from one dispenser. These results show that fabricated vapor cells are filled with Rb without degassing or leaks, and the reliability of the fabrication process and the production efficiency can be expected. Rb vapor cell sealed in the controlled pressure with buffer gases N2/Ar is also fabricated and evaluated. The spectrum line is broadened, and CPT resonance peak is narrowed 4.0 kHz at 90 °C. These results show the proposal fabrication method of the alkali vapor cells is useful for miniature atomic clocks.
Simple-design ultra-low phase noise microwave frequency synthesizers for high-performing Cs and Rb vapor-cell atomic clocks