# Nonlinear Waves and Turbulence in Photonics 2022 - Abstract

**Skryabin, Dmitry**

*Chi-2 combs and solitons in high-finesse microresonators*

I will outline some topics the Bath group has examined recently concerning the operation of the high-finesse chi-2 microring resonators with the large difference in the omega and two-omega group velocities. I will consider both the OPO and SHG pump arrangements. First, I will discuss the phase-matching conditions and demonstrate that the adiabatic elimination of the SHG component cannot be typically applied for all the modes, but that one or several modes should often be treated separately and present the respective reduced model [1]. Then, I will demonstrate that the tuning of the frequency of the parametric down-conversion is described by a discrete ladder-like sequence of the Eckhaus instabilities [1]. I will introduce and explain the staggered spectral patterns of frequency combs that are specific to OPOs [1]. In the SHG case I will demonstrate that the non-adiabatic modes lead to the Rabi flops and photon-photon polaritons [2,3]. I will then introduce physical mechanisms that allow to modelock dense two-color spectra and lead to the generation of chi-2 solitons despite the large offset of the group velocities across the optical octave. I will also propose a criterion for distinguishing the quasi-Kerr and quasi-Pockels solitons [4]. I will compare the theory and experiments where possible [5].

**References**:

[1] Puzyrev, DN, Skryabin, DV, Commun Phys 5, 138 (2022).

[2] DV Skryabin, VV Pankratov, A Villois, DN Puzyrev, Phys. Rev. Research 3, L012017 (2021).

[3] DN Puzyrev, VV Pankratov, A Villois, DV Skryabin, Physical Review A 104, 013520 (2021).

[4] DV Skryabin, Optics Express 29, 28521 (2021).

[5] N Amiune, DN Puzyrev, VV Pankratov, DV Skryabin, K Buse, I Breunig, Optics Express 29, 41378 (2021).