Direct generation of optical frequency combs in $\chi^{(2)}$ nonlinear cavities

TL;DR

This paper reviews recent advances in directly generating optical frequency combs using quadratic nonlinear cavities, highlighting theoretical models, stability analysis, and potential for efficient comb synthesizers.

Contribution

It extends the three-wave spectral model to many modes and provides a stability analysis, advancing understanding of direct comb generation in $ ext{chi}^{(2)}$ nonlinear cavities.

Findings

Generalized spectral model to many modes

Stability analysis of cavity regimes

Foundation for efficient $ ext{chi}^{(2)}$ comb synthesizers

Abstract

Quadratic nonlinear processes are currently exploited for frequency comb transfer and extension from the visible and near infrared regions to other spectral ranges where direct comb generation cannot be accomplished. However, frequency comb generation has been directly observed in continuously-pumped quadratic nonlinear crystals placed inside an optical cavity. At the same time, an introductory theoretical description of the phenomenon has been provided, showing a remarkable analogy with the dynamics of third-order Kerr microresonators. Here, we give an overview of our recent work on $\chi^{(2)}$ frequency comb generation. Furthermore, we generalize the preliminary three-wave spectral model to a many-mode comb and present a stability analysis of different cavity field regimes. Although at a very early stage, our work lays the groundwork for a novel class of highly efficient and versatile frequency comb synthesizers based on second-order nonlinear materials.