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Using a chip-based microcomb, full dimensional control of structured microwaves is demonstrated, including vortex-microwave generation, submicrosecond spatiotemporal mode switching, broadband phase–frequency response tuning and wide-angle two-dimensional beam steering. These capabilities are applied in a structured-microwave-based integrated sensing and communication system.

Using silicon nitride waveguides processed by plasma-enhanced chemical vapour deposition, full integration of ultrahigh-Q resonators with other photonic devices is now possible, representing a critical advance for future photonic circuits and systems.

Here, the authors demonstrate the use of chaos to obtain 2-octave comb generation. The deformation lifts the circular symmetry and creates chaotic tunneling channels that enable broadband collection of intracavity emission with a single waveguide, introducing a new degree of freedom to microcomb studies.

A turnkey regime for soliton microcombs is demonstrated, in which solitons are generated by switching on a co-integrated pump laser, eliminating the need for photonic and electronic control circuitry.

Dispersion engineering is pivotal in nonlinear photonics but traditionally fixed by post-fabrication immutability. Here, the authors demonstrate integrated chalcogenide microresonators with arbitrarily reconfigurable dispersion, providing a scalable and reprogrammable architecture for multifunctional photonic circuits.

Two-color lasers often suffer from low coherence at large frequency spacings. Herein, the authors use the Pound-Drever-Hall technique to synchronize two lasers to a common ultra-stable optical cavity, achieving high coherence and generating microwave signals with remarkable phase noise via 2-point frequency division.

Dissipative Kerr solitons in microresonators have recently been shown to generate frequency combs via Cherenkov radiation. Here, Yiet al. demonstrate hysteresis behaviour and a single-mode dispersive wave that can improve the stability of microcombs.

In order to study the dynamics of solitons in microresonators, which underlie nonlinear phenomena like Kerr comb generation, both high temporal resolution and long record times are needed. Here, the authors develop a coherent sampling method to directly image the temporal behavior of solitons.

Dark pulse microcombs have been realized in dissipation-engineered lithium niobate microresonators, unlocking broadband, high-power coherent light sources for communication and microwave applications in integrated lithium niobate photonic.

Chip-based microresonator frequency combs are currently limited to the infrared spectral region. Here, the authors generate combs whose center frequency approaches the visible spectrum enabled by combining geometrical and mode-hybridization dispersion control in silica microresonators.

A compact optical frequency division system with magnesium-fluoride-microresonator-based frequency references and silicon-nitride-microresonator-based comb generators is reported, offering a soliton pulse train at 25-GHz microwaves with an absolute phase noise of –141 dBc Hz^–1 and timing noise below 546 zs Hz^–1/2 at a 10-kHz offset frequency.

Optical absorption and nonlinear index are important performance drivers in devices like microcombs. Here the authors use resonance-enhanced nonlinear spectroscopy to characterize absorption limits and nonlinear index for some integrated photonic materials.

Here the authors explore the noise spectrum of soliton microcomb when the pump is decoupled from the solitons motion by balancing the Raman shift with the emitted dispersive wave. Based on the analysis of the phase noise and the soliton repetition rate, they identify the uncorrelated thermal fluctuations as underlying mechanism.

Using CMOS-ready ultra-high-Q microresonators, a highly coherent electrically pumped integrated laser with frequency noise of 0.2 Hz² Hz⁻¹, corresponding to a short-term linewidth of 1.2 Hz, is demonstrated. The device configuration is also found to relieve the dispersion requirements for microcomb generation that have limited certain nonlinear platforms.

Counter-propagating solitons are generated in microresonator systems, producing dual-soliton frequency-comb streams with different repetition rates but high relative coherence useful for spectroscopy and laser ranging systems.

Solitonic modes that are redshifted due to a Raman-related effect are reported in optical microcavities, and termed Stokes solitons.

A Sagnac gyroscope based on Brillouin ring lasers on a silicon chip is presented. The stability and sensitivity of this on-chip planar gyroscope allow measurement of the Earth’s rotation, with an amplitude sensitivity as small as 5 deg h⁻¹ for a sinusoidal rotation, an angle random walk of 0.068 deg h^−1/2 and bias instability of 3.6 deg h⁻¹.

Natural vibrations of mesoscopic particles, such as living cells, are typically faint; occurring at megahertz to gigahertz frequencies also makes detection challenging. Now, researchers demonstrate real-time measurement of natural vibrations of single mesoscopic particles by using photoacoustic excitation and acoustic coupling to an optical microresonator for readout.

Nonlinear microring resonators can generate a vortex soliton microcomb, that is, a frequency comb with each comb line carrying a distinct orbital angular momentum.

Achieving high output power and low noise integrated lasers is a major challenge. Here the authors experimentally demonstrate integrated lasers from a Si/SiN heterogeneous platform that shows Hertz-level linewidth, paving the way toward fully integrating low-noise silicon nitride photonics in volume using real devices for lasing.

Authors report quantum decoherence of dissipative Kerr solitons in normal-dispersion microresonators, also known as dark pulses. They show the quantum decoherence of dark pulses and their potential advantages over bright solitons in an AlGaAs-on-insulator system.

Despite larger nonlinear coefficients, waveguide losses have prevented using semiconductors instead of dielectric materials for on-chip frequency-comb sources. By significantly reducing waveguide loss, ultra-low-threshold Kerr comb generation is demonstrated in a high-Q AlGaAs-on-insulator microresonator system.

Quantum jitter fundamentally limits the performance of microresonator frequency combs. The timing jitter of the solitons that generate the comb spectra is analysed, reaching the quantum limit and establishing fundamental limits for soliton microcombs.