Optical amplifier

Statistics

Parametric statistics

Frequency modulation

Optics

Physics

Modulation (music)

Frequency comb

Parametric oscillator

Materials science

Instability

Acoustics

Optical parametric oscillator

Optical frequency comb

Mathematics

Computer science

Laser

Quantum mechanics

Radio frequency

Telecommunications

Nonlinear optics

Optical parametric amplifier

Physical Review Letters

Continuously pumped passive nonlinear cavities can be harnessed for the creation of novel optical frequency combs. While most research has focused on third-order "Kerr" nonlinear interactions, recent studies have shown that frequency comb formation can also occur via second-order nonlinear effects. Here, we report on the formation of quadratic combs in optical parametric oscillator (OPO) configurations. Specifically, we demonstrate that optical frequency combs can be generated in the parametric region around half of the pump frequency in a continuously driven OPO. We also model the OPO dynamics through a single time-domain mean-field equation, identifying previously unknown dynamical regimes, induced by modulation instabilities, which lead to comb formation. Numerical simulation results are in good agreement with experimentally observed spectra. Moreover, the analysis of the coherence properties of the simulated spectra shows the existence of correlated and phase-locked combs. Our results reveal previously unnoticed dynamics of an apparently well assessed optical system, and can lead to a new class of frequency comb sources that may stimulate novel applications by enabling straightforward access to elusive spectral regions, such as the midinfrared.

Modulation Instability Induced Frequency Comb Generation in a Continuously Pumped Optical Parametric Oscillator