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Optical frequency combs are conventionally defined as a set of phase-locked, equally spaced spectral lines. Here, using a two-dimensional array of Floquet topological ring resonators, the authors propose novel incommensurate combs with phase-locked spectral lines that are not all equally spaced.

Full tomography of biphoton frequency comb states requires frequency mixing operations which are hard to scale. Here, the authors propose and demonstrate a protocol exploiting advanced Bayesian statistical methods and randomized measurements coming from complex mode mixing in electro-optic phase modulators.

By controlling the group velocity dispersion of a microresonator through proper shape design, scientists generate a comb whose central frequency can be tuned throughout the transparency window of the microresonator host material.

Coherent control is a powerful tool for controlling light–matter interactions in time and frequency. Now, scientists show that counter-propagating broadband pulses can be used to generate fully controlled spatial excitation patterns. This spatial control approach also reduces decoherence, providing a high-frequency resolution similar to that of an optical frequency comb.

New evidence suggests a possible collaboration between the crop fungus, a weedy fungus and symbiotic bacteria in Odontotermes obesus fungus gardens that prevents the growth of unwanted fungi.

Optical frequency combs power technologies like communication but face stability issues in miniaturization. Here, authors present a self-locked microcomb in a lithium niobate chip by combining electro-optic, Kerr, and Raman effects, achieving a 300 nm span and low noise without external feedback.

Up to three distinct frequency combs are simultaneously generated from an optical microresonator and a continuous-wave laser, enabling the deployment of dual- and triple-comb-based methods to applications unachievable by current technologies.

An integrated device that combines optical parametric oscillation and electro-optic modulation in lithium niobate creates a flat-top frequency-comb-like output with low power requirements.

By pairing an octave-spanning terahertz microcomb with a terahertz Vernier microcomb, a continuous-wave laser at 871 nm is frequency divided to a radiofrequency clock output at 235 MHz. This laser is designed for frequency doubling to reach the ytterbium ion clock transition at 435.5 nm.

Spectrally resolved photoacoustic images often require the acquisition of data for each wavelength separately. Here, the authors use dual frequency-comb spectroscopy for photoacoustic measurements, enabling spectrally resolved measurements without the need to scan the illumination wavelength.

A broadband multi-frequency Fabry–Pérot laser diode, when coupled to a high-Q microresonator, can be efficiently transformed to an ~100 mW narrow-linewidth single-frequency light source, and subsequently, to a coherent soliton Kerr comb oscillator.

Using electro-optically generated frequency combs, scientists demonstrate radiofrequency photonic filters that can potentially provide simultaneous high stopband attenuation, fast tunability and bandwidth reconfiguration.

The Casimir effect is based on quantum electrodynamical effects between two electrically neutral objects in close proximity. Here Zou et al. observe the Casimir effect between two silicon components on a single micromechanical chip, allowing for an on-chip exploitation of the Casimir force.

Dual frequency combs are a powerful tool for a range of optical measurements and technologies. The authors here generate orthogonally polarized dual combs with exceptionally high relative stability.

Here, the authors demonstrate full stabilization and control of the two key parameters of a four-wavemixing-based quantum cascade laser comb with metrological precision. These fully-controlled, frequency scalable comb emitters will allow an increasing number of mid- and far-IR applications.

Dual-comb spectroscopy has become a valuable tool for broadband high-resolution measurements. Here Bergevin et al. apply this technique to a laser-induced plasma detecting different species in a solid sample with a spectral resolution sufficient to resolve hyperfine splitting of the Rb D₂ line.

Frequency metrology lies at the heart of precision measurement. Here, authors establish a phasecoherent frequency link across microwave, optical, and free-electron domains. This bridges electromagnetic waves and electron matter waves, advancing ultrahigh-precision electron spectroscopy.

Using two coherent broadband fibre-laser frequency comb sources, a coherent laser ranging system for absolute distance measurements is demonstrated. Its combination of precision, speed and long range may prove particularly useful for space-based sciences.

Photonic solutions for generating free space millimeter radiation is a fast developing field that combines optoelectronics and RF domains but has many challenges. Here the authors present a quantum cascade laser (QCL) based solution for THz laser emission and millimeter wave generation in a single device.

There is considerable interest in generating broadband frequency combs at terahertz frequencies. Here, Tammaro et al.achieve this using coherent synchrotron radiation where the electron bunches emit quasi-synchronous terahertz pulses with high power, broad frequency, zero frequency offset, and high density.

Laser frequency combs emit a spectrum of equally spaced peaks that can provide precise frequency references useful for astronomy. Here, the authors demonstrate a frequency comb using electro-optical modulation, which has a line spacing that is resolvable using grating spectrographs unlike the mode-locking approach.

A microcomb source based on a silicon nitride ring resonator is shown to support petabit-per-second data transmission over a multicore optical fibre.

Single-mode, tuneable monolithic semiconductor lasers are important light sources for integrated photonics. Here, Kundu et al. observe the switch-on dynamics and mode competition of a terahertz quantum cascade laser and explain the behaviour with a carrier and photon transport model.

Chip-based frequency combs promise many applications, but full integration requires the electrical pump source and the microresonator to be on the same chip. Here, the authors show such integration of a microcomb with < 100 GHz mode spacing without additional filtering cavities or on-chip heaters.

Ultrafast lasers with multi-gigahertz repetition rates are desirable for applications requiring high sampling rates or resolvable frequency comb lines. Here, Mayer et al. use cascading of quadratic nonlinearities to passively modelock a femtosecond solid-state laser at a repetition rate of 10 GHz.

Increasing the conversion efficiency of soliton crystals will enable further application of optical frequency comb. Here the authors engineer an hybrid Mach-Zehnder micro-ring resonator to achieve 80% pump-to-comb conversion efficiency based on dissipative Kerr solitons.

The draft genome of the ctenophore Pleurobrachia bachei (Pacific sea gooseberry) is presented, together with ten other ctenophore transcriptomes — these genomes have a very different neurogenic, immune and developmental gene content when compared with other animal genomes, and it is proposed that ctenophore neural systems, and possibly muscle specification, evolved independently from those in other animals.

An optical frequency comb demodulated on a photodiode can generate a radio frequency signal with high spectral purity at a frequency corresponding to the comb spacing. Here, Liang et al.demonstrate a frequency-comb-based radio frequency photonic oscillator characterized with low phase noise and high frequency stability.

The observation of soliton crystals in monolithic Kerr microresonators is reported. The physics of such resonators is explored in a regime of dense soliton occupation, offering a way to increase the efficiency of Kerr combs.

Feng et al. compare the genome-wide binding and activity of two Drosophila Hox transcription factors that determine the identities of different fly legs. For binding events that are Hox specific, two cofactors, Exd and Dll, are used to achieve specificity in non-overlapping leg domains.

Atomic clocks using optical transitions have much better frequency stability compared to microwave counterparts, but are also more complex, which means their use has been mostly lab-based so far. Here, the authors demonstrate successful operation of three different optical atomic clocks on a ship at sea for three weeks.

On-chip nonlinear optics can be used to manipulate classical or quantum signals but enhancement of competing nonlinear processes can cause signal distortion. Here, Merklein et al. enhance and inhibit nonlinear scattering on a chip by tailoring the optical density-of-states at the edge of a photonic bandgap.

Fourier transform spectrometers are generally limited to slow scanning rates at high resolution. Here the authors demonstrate highly efficient Fourier transform spectroscopy using a dynamic phase-control technique that enables fast acquisition without compromising bandwidth or resolution.

Photonic, electronic and lattice resonances in patterned semiconductor microcavities are tailored to demonstrate coherent bidirectional microwave-to-optical conversion via phonon-exciton-photon quasi-particles in the strong-coupling regime.

By monolithically integrating piezoelectric actuators on ultralow-loss photonic circuits, soliton microcombs—a spectrum of sharp lines over a range of optical frequencies—can be modulated at high speeds with megahertz bandwidths.

By leveraging microcavity-integrated photonics and Kerr-induced optical frequency division, an integrated photonic millimetre-wave oscillator with low phase noise is demonstrated, achieving –77 dBc Hz^–1 and –121 dBc Hz^–1, respectively, at 100-Hz and 10-kHz offset frequencies, corresponding to –98 dBc Hz^–1 and –142 dBc Hz^–1 when scaled to a 10-GHz carrier.

Silicon ICs are key to neural implants but face reliability challenges. Here, the authors show bare die ICs can be inherently hermetic, and PDMS encapsulation limits degradation over 12 months, offering insights to enhance active implant longevity for biomedical use.

Tuneable microresonator frequency combs offer low-power, coherent light with a small device footprint. Here, the concept of controlling the comb frequency by detuning the probe phase is translated from photonic crystal fibres to a Kerr microresonator.

The authors demonstrate a multi-dimensional communication scheme that combines wavelength- and mode- multiplexing on photonic integrated circuits using foundry-compatible photonic inverse design and spectrally flattened microcombs

The temporal structure of the polarization and carrier-envelope phase slip of high-harmonic waveforms generated in bulk gallium selenide within the duration of a single multi-terahertz driving pulse can be controlled by the crystal symmetry.

Optical frequency combs enable precise measurement of optical frequencies, but integrated setups require a delicate balance between high precision and low power consumption. The authors demonstrate a sub-kHz-frequency measurement scheme based on a fully stabilized electro-optic comb that enables the parallel measurement of multiple wavelengths.