Tailoring microcombs with inverse-designed, meta-dispersion microresonators

Abstract

Nonlinear-wave mixing in optical microresonators offers new perspectives to generate compact optical-frequency microcombs, which enable an ever-growing number of applications. Microcombs exhibit a spectral profile that is primarily determined by their microresonator's dispersion; an example is the ${\mathrm{sech}}^2$ spectrum of dissipative Kerr solitons under anomalous group-velocity dispersion. Here, we introduce an inverse-design approach to spectrally shape microcombs, by optimizing an arbitrary meta-dispersion in a resonator. By incorporating the system's governing equation into a genetic algorithm, we are able to efficiently identify a dispersion profile that produces a microcomb closely matching a user-defined target spectrum, such as spectrally-flat combs or near-Gaussian pulses. We show a concrete implementation of these intricate optimized dispersion profiles, using selective bidirectional-mode hybridization in photonic-crystal resonators. Moreover, we fabricate and explore several microcomb generators with such flexible `meta' dispersion control. Their dispersion is not only controlled by the waveguide composing the resonator, but also by a corrugation inside the resonator, which geometrically controls the spectral distribution of the bidirectional coupling in the resonator. This approach provides programmable mode-by-mode frequency splitting and thus greatly increases the design space for controlling the nonlinear dynamics of optical states such as Kerr solitons.

16 pages, includes SI

References in corpus (5)

• Stably accessing octave-spanning microresonator frequency combs in the soliton regime
• Frequency combs and platicons in optical microresonators with normal GVD
• Probing material absorption and optical nonlinearity of integrated photonic materials
• Fourier synthesis dispersion engineering of photonic crystal microrings for broadband frequency combs
• A hierarchy of coupled mode and envelope models for bi-directional microresonators with Kerr nonlinearity

Cited by in corpus (10)

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• Mesoscopic ultrafast nonlinear optics -- The emergence of multimode quantum non-Gaussian physics
• Spectral engineering of optical microresonators in anisotropic lithium niobate crystal
• Soliton Microcomb Generation in a III-V Photonic Crystal Cavity
• Multi-mode microcavity frequency engineering through a shifted grating in a photonic crystal ring
• Scalable freeform optimization of wide-aperture 3D metalenses by zoned discrete axisymmetry
• Optimization of the degenerate optical parametric oscillations threshold in bichromatically pumped microresonator
• Self-cooling, blue-detuned dissipative Kerr microresonator soliton comb
• Reconfigurable Non-Hermitian Soliton Combs using Dissipative Couplings and Topological Windings