Microfabricated strontium atomic vapor cells.

We demonstrate strontium (Sr) atomic vapor cells having a total external volume of 0.63 cm that can operate above 300 °C for times exceeding 380 h. The cells are fabricated using micromachined silicon frames anodically bonded to glass windows that have a 20-nm thick protective layer of AlO deposited on the interior surfaces. The presence of Sr vapor in the cell is confirmed through laser absorption spectroscopy for the S → P transition in Sr at 461 nm. Measurements of sub-Doppler linewidths indicated negligible (<3 MHz) broadening of this transition from residual background gas collisions. This compact and manufacturable, high-temperature atomic vapor cell can enable narrow-line optical frequency references based on strontium and other alkaline earth species.