Spectral Broadening in a Continuously Pumped Singly Resonant Second-Harmonic Cavity

Year: 2021

Authors: Mosca S., Hansson T., Parisi M.

Autors Affiliation: CNR-INO, Istituto Nazionale di Ottica, Via Campi Flegrei 34, I-80078 Pozzuoli, NA, Italy

Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping, Sweden

Abstract: Optical frequency comb synthesizers with a wide spectral range are an essential tool
for many research areas such as spectroscopy, precision metrology, optical communication, and
sensing. Recent studies have demonstrated the direct generation of frequency combs, via secondorder
processes, that are centered on two different spectral regions separated by an octave. Here, we
present the capability of optical quadratic frequency combs for broad-bandwidth spectral emission in
unexplored regimes. We consider comb formation under phase-matched conditions in a continuouswave
pumped singly resonant second-harmonic cavity, with large intracavity power and control of
the detuning over several cavity linewidths. The spectral analysis reveals quite distinctive sidebands
that arise far away from the pump, singularly or in a mixed regime together with narrowband
frequency combs. Notably, by increasing the input power, the optical frequency lines evolve into
widely spaced frequency clusters, and at maximum power, they appear in a wavelength range
spanning up to 100 nm. The obtained results demonstrate the capacity of second-order nonlinearities
to produce direct comb within a wide range of wavelengths.


Volume: 11      Pages from: 1  to: 10

More Information: This research was supported in part by European Union´s Horizon 2020 research and innovation program (Qombs Project, FET Flagship on Quantum Technologies Grant. No. 820419). T.H. acknowledges funding from the Swedish Research Council (Vetenskapsradet, Grant. No. 2017-05309).
KeyWords: optical frequency combs; quadratic nonlinearity; second-harmonic generation
DOI: 10.3390/app11157122