Shelving Spectroscopy of the Strontium 689 nm intercombination line in a Microfabricated Vapor Cell

Alkaline earth atoms have been the work horse for the state-of-the-art optical lattice clocks and widely used in neutral atom-based quantum computing. Vapor cells containing alkaline earth atomic vapor, such as heat pipes and hollow cathode lamps, are used for locking the broad and narrow line cooling lasers in the cold atom experiments. However, they suffer from bulk size, expensive cost and potential contamination. Here we demonstrate linewidth below 200 kHz for the Sr ¹S₀ to ³P₁ intercombination line in a microfabricated vapor cell with 9 x 14 x 3 mm³ dimension. The narrow linewidth puts a 10 mTorr upper limit of the residual gas pressure in these vapor cells. The microfabricated alkaline earth vapor cells could provide a cheap and scalable way to lock the lasers in cold atom experiments, as well as to build vapor cell-based compact optical frequency references, thermometers, and magnetometers.