Fig. 5: Spectroscopic measurements of cesium vapor cells equipped with break-seal structures.
From: Wafer-level vapor cells filled with laser-actuated hermetic seals for integrated atomic devices
a The cell shown in Fig. 4d has been monitored with linear absorption spectroscopy for almost 6 months, during which 3 reservoirs have been sequentially opened. This is well visible in the evolution of contrast and FWHM of absorption lines recorded during sequential activation of break-seals, where contrast is decreased and FWHM increased stepwise. b The same cell (BS-EL) has afterwards been measured on a coherent population trapping (CPT) clock bench for nearly 1 month. The clock frequency drift is measured at the level of 0.06 Hz/day, i.e. 6.5 × 10−12 fractional frequency stability at one day, despite a remaining adjacent gas reservoir filled with 186 Torr of neon
