Optical frequency combs (OFC) are light sources consisting of a regular array of narrow spectral lines. They are naturally generated by optical resonators, for instance those necessary to make a laser work.
OFC find many applications in high-resolution chemical spectroscopy, optical metrology and are considered as the next generation source of precise timing. Because of the big technological impact of these applications, prof. Theodor Hänsch received the Noble prize in 2005 for his outstanding contribution to the development and use of OFC.
OFC have recently received great interest from the astronomical community because they can be used for the absolute calibration of high-resolution spectrographs. They are currently used in spectrographs devoted to the discovery and characterization of Earth-like extrasolar planets.
The “Optical Frequency Combs” activity at the ‘Integrated Astrophotonic’ group includes both numerical and experimental investigation on the generation and stabilization of broad-band, near-infrared frequency combs in SiN microring resonators, optimized for the calibration of mid- to high-resolution spectrographs (R>25000).
The experimental activities will try to verify the viability to two different stabilization schemes of the microring cavities by setting up and testing a few technology demonstrators. The most successful scheme will be eventually engineered for a test on sky at a suitable astronomical observatory.