Alkali metal-wax micropackets for chip-scale atomic clocks

We report a novel methodology for fabrication of vapor cells for chip-scale atomic clocks (CSAC) using wafer-scale micromachining processes. Alkali metals are enclosed in a chemically inert wax to preform alkali metal-wax micropackets, keeping the alkali metals from reacting with the ambient during the vapor cell fabrication. Apart from the high level of purity of the alkali metals in the resulting vapor cells, this method holds promise for inexpensive and flexible manufacturing of vapor cells, as well as easy handling of alkali metals used for a variety of applications other than for CSAC. The optical absorption on fabricated rubidium-87 (Rb⁸⁷) vapor cells over the D2 transitions of Rb⁸⁷ shows a contrast of more than 65%, important to the frequency stability of CSAC.