Photon-photon polaritons in chi-2 microresonators

• Published in: 2021 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) p. 1
• Main Authors: Skryabin, D.V., Pankratov, V., Villois, A., Puzyrev, D.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 21-06-2021
• Subjects: Amplitude modulation; Atom optics; Couplings; Harmonic analysis; Microcavities; Optical coupling; Optical pumping
• DOI: 10.1109/CLEO/Europe-EQEC52157.2021.9541787

We consider a high-Q microresonator with chi-2 nonlinearity under conditions when the coupling rate between the sidebands around the pump and its second harmonic exceeds the damping rates, implying the strong coupling regime (SC). Using the dressed-resonator methodology, which is similar to the well-known theory of the two-levels atoms dressed by the optical fields, we demonstrate that this regime leads to the dominance of the reversible energy transfer between the sidebands over the non-reversible sideband growth due to parametric gain. This observation has allowed us to introduce and apply the cross-area concept of the polariton quasi-particles in the context of chi-2 ring-microresonators, and to use it to predict the modified spectral response of the resonator to the weak probe field. This response reveals the splitting of the bare-resonator resonances, avoided crossings, and Rabi dynamics. Using polaritons as the basis has also allowed us to derive a discrete sequence of the parametric thresholds for generation of sidebands of different orders. These thresholds form spectacular patterns in the parameter space defined by the detunings of the fundamental and 2 nd harmonic fields, Figs (a) and (b).