Microresonatorbased

Microresonator-based devices refer to systems in which light is confined and stored in a small optical resonator to amplify light–matter interactions. Common architectures include ring and disk resonators, whispering-gallery-mode structures, and photonic-crystal cavities. These devices typically exhibit high quality factors and small mode volumes, enabling long photon lifetimes and strong nonlinearities even at modest input powers.

Operation relies on evanescent coupling between a waveguide and the resonator, allowing light to enter and exit the resonator with controlled loading. The resonator supports a series of resonant modes spaced by the free spectral range, and its performance is governed by the quality factor, coupling regime, and dispersion. Nonlinear optical effects, particularly the Kerr nonlinearity, enable phenomena such as four-wave mixing, parametric oscillation, and, in certain regimes, dissipative Kerr solitons that form stable microresonator-based frequency combs spanning broad spectral ranges.

Materials and fabrication platforms for microresonator-based devices include silicon nitride, silicon-on-insulator, lithium niobate on insulator, aluminum nitride, and silica. Fabrication typically employs lithography and etching processes compatible with CMOS tools, which supports potential monolithic integration with other photonic and electronic components.

Applications are diverse. Microresonator-based Kerr frequency combs serve precision metrology, optical clocks, spectroscopy, and wavelength-division multiplexed communications. They are also used in sensing, nonlinear signal processing, microwave photonics, and emerging quantum photonics platforms. Ongoing research aims to improve dispersion engineering, increase quality factors, manage thermal effects, and enable scalable integration with electronic circuits.

Challenges include fabrication variability leading to resonance offset, thermal detuning, reliable dispersion control, and packaging for real-world environments. Despite these hurdles, microresonator-based technologies continue to advance as compact, high-performance building blocks in integrated photonics.