Lasers precisely stabilized to known transitions between energy levels in simple, well-isolated quantum systems such as atoms and molecules are essential for a plethora of applications in metrology and optical communications. The implementation of such spectroscopic systems in a chip-scale format would allow to reduce cost dramatically and would open up new opportunities in both photonically integrated platforms and free-space applications such as lidar. 

We demonstrated the first integrated-photonic frequency reference based on acetylene telecom transitions.

https://onlinelibrary.wiley.com/doi/full/10.1002/lpor.201900414