Towards Sr shelving spectroscopy based in microfabricated vapor cells*

The 7 kHz Sr intercombination line at 689 nm could be used to implement an optical clock with a frequency instability below 10^-13 at 1s. Optical “shelving” detection provides a simple scheme to detect the 7 kHz transition in hot Sr vapors, making it possible to miniaturize the clock with the help of a microfabricated vapor cell. To perform shelving spectroscopy, a narrow linewidth laser at 689nm of the Sr intercombination line is needed. We achieved this by phase locking the 689 nm laser to a frequency comb. A 461 nm laser probing the ¹S₀ to ¹P₁ transition is frequency locked using saturation absorption spectroscopy. We will report on the progress of using the two lasers for shelving spectroscopy in a microfabricated Sr vapor cell.