Search

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.

Integrated optical frequency combs are powerful tools for optical spectroscopy. Here, authors demonstrate low-power, detectable-rate soliton microcombs from telecom to visible bands, including wavelength-multiplexed operation, using ultra-low-loss silicon nitride waveguides.

Colloidal perovskite quantum dots hold promise for polaritonic devices with strong excitonic confinement. Here the authors report the observation of room-temperature cavity exciton-polariton condensation in a perovskite-based quantum dot solid, opening the door towards quantum and photonics applications.

An ultra-compact, ultra-wide-bandwidth in-phase/quadrature modulator on a silicon chip is demonstrated, enabling coherent transmission for symbol rates up to 180 Gbaud and a net bit rate surpassing 1 Tb s⁻¹ over an 80 km span, with modulation energy consumption as low as 10.4 fJ bit⁻¹, and promising enhanced performance and scalability for future networking infrastructures.

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.

Microresonator frequency combs are versatile tools for sensing, data transmission and quantum applications. In this work the authors present the generation of low-noise frequency combs at repetition rates of 100 GHz by utilizing a cascaded forward-propagating Brillouin scattering process to seed soliton frequency comb generation.

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.

Topological lasers often suffer from low directionality, and/or complex design requirements hindering operation at small wavelengths. Here, by using a few monolayers of perovskite quantum dots, the authors demonstrate a lithography-free, vertical-emitting, single-mode laser emitting in the green.

Constructing ultraviolet lasing is of great significance for basic research and medical use. Here the authors present a strategy for generating ultraviolet lasing through a tandem upconversion process with ultralarge anti-Stokes shift (1260 nm).

For advanced microcomb applications, the exact detection of the high repetition rate becomes difficult due to the limited bandwidth of the photodiodes. Here, the authors present a Vernier dual-comb method to sample the main soliton comb and divide the repetition rate by a generating low frequency beat notes.

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.

The intrinsic Kerr nonlinearity in ring resonators is exploited to demonstrate passive isolation of a continuous-wave laser. Up to 35-dB isolation with 5-dB insertion loss was achieved on-chip.

A label-free and low-cost sensor capable of detecting several biomarkers in parallel is a sought-after medical tool. Here, the authors describe an approach exploiting both photonic and electrochemical properties of silicon to build a multi-___domain biosensor for label-free and multiplexed detection.

Optical metrology applications require lasers with high spectral purity but on-chip devices with sub-100 Hz linewidth are yet to be realized. Here, Liang et al.present a heterogeneously integrated, chip-scale semiconductor laser with 30 Hz integral linewidth and sub-Hz instantaneous linewidth.

Micromechanical oscillators present a route to miniaturisation of devices and may be used as frequency references or sensitive sensors, but their small size means that they often behave nonlinearly. Antonioet al. demonstrate frequency stabilisation of nonlinear resonators by coupling two vibrational modes.

Coherent coupling of light with electronic transitions has led to phenomena such as polariton lasing and superfluidity. Shalabney et al.now couple the optical modes of micro-cavity to the vibrational modes of a molecule at room temperature and thereby alter the chemical behaviour of the molecule.

Non-reciprocal optical elements usually require the presence of magnetic fields, which makes chip integration difficult. Here, Hua et al. demonstrate a non-magnetic optical isolator with bidirectional injection on a silicon platform utilizing parametric amplification in four-wave mixing.

Masers are promising for applications that use microwave radiation. Here, the authors present a compact room-temperature maser design using a high permittivity dielectric material for the resonator to achieve low optical pumping powers. This design pushes masers closer towards their promised applications.

Whispering-gallery mode microresonators are powerful sensing tools, but spectrum acquisition has taken milliseconds or longer. Here, Rosenblum et al.introduce cavity ring-up spectroscopy, in which sharply rising detuned probe pulses capture spectra of microresonators on nanosecond timescales.

Macroscopic mechanical systems typically respond linearly to external force, and generating nonlinearity is challenging. Here, the authors generate nonlinearity in a macroscopic mechanical resonator by linking it to a gold contact and exploiting the anharmonicity in the chemical bonding interactions.

Stimulated Brillouin scattering is a non-linear interaction that allows light to be stored as coherent acoustic waves. Here, the authors report on Brillouin scattering-induced transparency in an optical microresonator whose high quality allows for long-lifetime non-reciprocal light storage.

The breaking of parity-time symmetric gain and loss profiles can be used to achieve single-mode lasing in coupled microring resonators. Here, Liuet al. show that this effect can be electrically controlled with a tunable lasing wavelength and strong sidemode suppression.

Optical frequency combs in the mid-infrared are required for molecular gas detection applications but their realization in compact microresonator-based platforms is challenging. Here, Griffith et al. demonstrate on-chip broadband comb generation on a silicon microresonator spanning from 2.1 to 3.5 μm.

Hybrid polariton states originating from the strong coupling of photonic and excitonic states hold promise for control of nonlinear light behaviour. Here, the authors fabricate a microcavity containing organic dye and WS₂, featuring hybrid polaritons arising from both Frenkel and Wannier-Mott excitons.

Breather solitons can be found in both physical and biological nonlinear systems. Here, Yuet al. demonstrate this type of soliton in silicon and silicon nitride microresonators, which advances the understanding of soliton-based comb-generation in microresonators.

Aligning the resonances of sets of optical cavities is necessary for advanced photonics and sensing applications. Here, the authors introduce resonant photoelectrochemical etching as a method to collectively and permanently tune the resonant wavelengths of ensembles of resonators on a photonic chip.

The quantum aspect of soliton microcomb from an integrated silicon carbide microresonator is studied in several regimes — below threshold, above threshold and in the soliton regime — using a single-photon optical spectrum analyser for second-order photon correlation measurement.

Researchers demonstrate an integrated mirror-symmetric non-reciprocal device enabled by three coupled photonic resonators. Nearly 40 dB of isolation is achieved at telecommunications wavelengths using 75 mW of radiofrequency power.

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.

The coupling between light and relativistic free electrons is enhanced through phase matching of electrons with optical whispering-gallery modes in dielectric microspheres and through extended modal lifetimes.

Heat flux is well understood on macroscopic scales, however when the system size is reduced, novel phenomena are induced by fluctuations. Here, the authors demonstrate phonon heat transport between two nanomechanical resonators coupled by cavity enhanced interactions exhibiting an oscillating heat flux.

Dual-comb spectroscopy is a powerful tool for realizing rapid spectroscopic measurements with high sensitivity and selectivity. Here, Yu et al. demonstrate silicon microresonator-based dual comb spectroscopy in the mid-infrared region, where strong vibrational resonances of many liquids exist.

A scalable solution involving direct wafer-bonding of high-quality, epitaxially grown gallium phosphide to low-index substrates is introduced. The promise of this platform for integrated nonlinear photonics is demonstrated with low-threshold frequency comb generation, frequency-doubled combs and Raman lasing.

Phenomena linked with ultrastrong coupling rely on the presence of virtual photons in the system’s ground state. In this article, using exact diagonalization, De Liberato shows that the population of ground state virtual photons is only quantitatively affected by losses.

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.

precisely controllable integrated optical gyroscope based on stimulated Brillouin scattering is used to study non-Hermitian physics, revealing a four-fold enhancement of the Sagnac scale factor near exceptional points.

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.

Frequency response shaping of a ‘racetrack’ ring resonator is demonstrated using a double injection configuration. Sinusoidal, triangular, square and other response shapes are shown.

Here, the authors demonstrate strain-induced, strong coupling between two adjacent nanomechanical pillar resonators for the investigation of collective dynamical phenomena. Both mode hybridization and the formation of an avoided level crossing in the response of the nanopillar pair are experimentally observed.

Upconversion nanoparticles, which convert lower-energy light into higher-energy light, have many potential applications including sensing and imaging. Here, Wen et al. review recent advances that have addressed concentration quenching and enabled increasingly bright nanoparticles, opening up their full potential.

Researcher demonstrate the line-by-line pulse shaping of frequency combs generated in silicon nitride ring resonators, and observe two distinct paths to comb formation that exhibit strikingly different time ___domain behaviours.

Ultrabroad-bandwidth radiofrequency pulses that increase data transmission rate and allow multipath tolerance in wireless communications are difficult to generate using chip-based electronics. Now, a chip-scale fully programmable spectral shaper consisting of cascaded multichannel micro-ring resonators is demonstrated as a solution.

By exploiting the interaction between light and phonons in a silica microsphere resonator it is possible to generate Brillouin scattering induced transparency, which is akin to electromagnetically induced transparency but for acoustic waves.

Microcavity polaritons—the bosonic quasiparticles that result from strong light–matter coupling—are observed for the first time in a dielectric cavity containing a monolayer of molybdenum disulphide at room temperature.

It is now shown that coupled optical microcavities bear all the hallmarks of parity–time symmetry; that is, the system’s dynamics are unchanged by both time-reversal and mirror transformations. The resonant nature of microcavities results in unusual effects not seen in previous photonic analogues of parity–time-symmetric systems: for example, light travelling in one direction is resonantly enhanced but there are no resonance peaks going the other way.

Light and matter excitations from host media can hybridize in the strong coupling regime, resulting in the formation of hybrid polariton modes. Here, the authors demonstrate hybridization between tightly bound excitons in a MoSe₂ monolayer and excitons in GaAs quantum wells via coupling to a cavity resonance.

Spontaneous parametric down-conversion was used to generate narrowband photon pairs with a high spectral brightness in a high-Q silicon nitride microresonator.

The strong electro-optic interaction, low optical loss and high microwave bandwidth of thin-film lithium niobate have enabled applications from computing to quantum information. This Review explores the fundamental principles, recent advances and the future potential of integrated lithium niobate technologies.