Vector vortex beams are conventionally created as the superposition of orbital angular momentum (OAM) modes with orthogonal polarizations, limiting the available degrees of freedom (DoFs) to 2, while their creation by complex optical devices such as metasurfaces, liquid crystals, and interferometers has hindered their versatility. Here we demonstrate a new class of vector vortex beam constructed from

The cost and power consumption of optical transmitters are now hampering further increases in total transmission capacity within and between data centers. Photonic integrated circuits (PICs) based on silicon (Si) photonics with wavelength-division multiplexing (WDM) technologies are promising solutions. However, due to the inefficient light emission characteristics of Si, incorporating III-V compound

Single photons coupled to atomic systems have shown to be a promising platform for developing quantum technologies. Yet a bright on-demand, highly pure, and highly indistinguishable single-photon source compatible with atomic platforms is lacking. In this work, we demonstrate such a source based on a strongly interacting Rydberg system. The large optical nonlinearities in a blockaded Rydberg ensemble

A robust approach for acquiring background-free, multitransition absorption spectra under single-laser-shot conditions is demonstrated using broadband, ultrashort laser pulses. This technique—referred to as time-resolved optically gated absorption (TOGA)—exploits the inherent differences in timescales between broadband, femtosecond-duration light sources and the longer-duration responses of narrowband

Vacuum-ultraviolet (VUV) light is critical for the study of molecules and materials, but the generation of femtosecond pulses in the VUV region at high repetition rates has proven difficult. Here we demonstrate the efficient generation of VUV light at megahertz repetition rates using highly cascaded four-wave mixing processes in a negative-curvature hollow-core fiber. Both even- and odd-order harmonics

We introduce Airy-beam tomographic microscopy (ATM) for high-resolution, volumetric, inertia-free imaging of biological specimens. The work exploits the highly adjustable Airy trajectories in the 3D space, transforming the conventional telecentric wide-field imaging scheme that requires sample or focal-plane scanning to acquire 3D information. The results present a consistent near-diffraction-limited

Rapid cryopreservation of biological specimens is the gold standard for visualizing cellular structures in their true structural context. However, current commercial cryo-fluorescence microscopes are limited to low resolutions. To fill this gap, we have developed cryoSIM, a microscope for 3D super-resolution fluorescence cryo-imaging for correlation with cryo-electron microscopy or cryo-soft X-ray

Working with finite numbers of modes to describe, generate, and detect optical fields can be both mathematically economical and physically useful. Such a modal basis can map directly to various applications in communications, sensing, and processing. But, we need a way to generate and analyze such fields, including measurement and control of both the relative amplitudes and phases of the modal components

Photodetectors are cornerstone components in integrated optical circuits and are essential for applications underlying modern science and engineering. Structures harnessing conventional crystalline materials are typically at the heart of such devices. In particular, group-IV semiconductors such as silicon and germanium open up more possibilities for high-performing on-chip photodetection thanks to

Eliminating light reflection from the top glass sheet in optoelectronic applications is often desirable across a broad range of wavelengths and large variety of angles. In this paper, we report on a combined simulation and experimental study of single-layer films, nanowire arrays, and nanocone arrays to meet these antireflection (AR) needs. We demonstrate the application of Bayesian learning to the

We propose a polarization-insensitive ultra-broadband mode filter based on a 3D graphene structure buried in a few-mode optical waveguide. Our experimental device fabricated by burying an L-shaped graphene structure in a three-mode polymer waveguide provides polarization-insensitive filtering of the fundamental mode, while keeping the higher-order modes, with a mode extinction ratio of ${\sim}{{17}}\;{\rm{dB}}$

In quantum illumination (QI), a signal beam initially entangled with an idler beam held at the receiver interrogates a target region bathed in thermal background light. The returned beam is measured jointly with the idler in order to determine whether a weakly reflecting target is present. Using tools from quantum information theory, we derive lower bounds on the average error probability of detecting

Tunable narrowband spectral filtering across arbitrary optical wavebands is highly desirable in a plethora of applications, from chemical sensing and hyperspectral imaging to infrared astronomy. Yet, the ability to reconfigure the optical properties, with full reversibility, of a solid-state large-area narrowband filter remains elusive. Existing solutions require either moving parts, have slow response

Fluorescence microscopy and derived techniques are continuously looking for photodetectors able to guarantee increased sensitivity, high spatial and temporal resolution, and ease of integration into modern microscopy architectures. Recent advances in single-photon avalanche diodes (SPADs) fabricated with industry-standard microelectronic processes allow the development of new detection systems tailored

Contrary to the usual assumption of at least partial control of quantum dynamics, a surprising recent result proved that an arbitrary quantum state can be probabilistically reset to a state in the past by having it interact with probing systems in a consistent but uncontrolled way. We present a photonic implementation to achieve this resetting process, experimentally verifying that a state can be probabilistically

High-dimensional entanglement enriches our understanding of entanglement and shows many advantages in quantum communications tasks, so its long-distance distribution is a key technology. Here, we use multicore fiber to distribute four-dimensional (4D) entanglement over 11 km. The observed fidelity is $F = 0.921 \pm 0.001$, which is feasible for high-dimensional quantum networks. We observed the violation

Global quantum networks for secure communication can be realized using large fleets of satellites distributing entangled photon pairs between ground-based nodes. Because the cost of a satellite depends on its size, the smallest satellites will be most cost-effective. This Letter describes a miniaturized, polarization entangled, photon-pair source operating on board a nano-satellite. The source violates

A critical challenge of pump-probe experiments with x-ray free-electron lasers (XFELs) is accurate synchronization of x-ray and optical pulses. At the European XFEL we observed megahertz rate timing jitter of ${24.0} \pm {12.4}\;{\rm fs}$.

Soft x-ray microscopy in the water window $({\sim}{285 {-} 535}\;{\rm eV}$) is an emerging and unique tool for 2D and 3D imaging of unstained intact cellular samples in their near-native state with few-10-nm detail. However, present microscopes rely on the high x-ray brightness of synchrotron-radiation sources. Having access to water-window microscopy in the home laboratory would increase the impact

Deep neural networks have emerged as effective tools for computational imaging, including quantitative phase microscopy of transparent samples. To reconstruct phase from intensity, current approaches rely on supervised learning with training examples; consequently, their performance is sensitive to a match of training and imaging settings. Here we propose a new approach to phase microscopy by using

Although blood hemoglobin (Hgb) testing is a routine procedure in a variety of clinical situations, noninvasive, continuous, and real-time blood Hgb measurements are still challenging. Optical spectroscopy can offer noninvasive blood Hgb quantification, but requires bulky optical components that intrinsically limit the development of mobile health (mHealth) technologies. Here, we report spectral super-resolution

Simultaneous measurements of single-molecule positions and orientations provide critical insight into a variety of biological and chemical processes. Various engineered point spread functions (PSFs) have been introduced for measuring the orientation and rotational diffusion of dipole-like emitters, but the widely used Cramér-Rao bound (CRB) only evaluates performance for one specific orientation at

As single-photon imaging becomes progressively more commonplace in sensing applications such as low-light-level imaging, three-dimensional profiling, and fluorescence imaging, there exist a number of fields where multispectral information can also be exploited, e.g., in environmental monitoring and target identification. We have fabricated a high-transmittance mosaic filter array, where each optical

Photonic waveguides are prime candidates for integrated and parallel photonic interconnects. Such interconnects correspond to large-scale vector matrix products, which are at the heart of neural network computation. However, parallel interconnect circuits realized in two dimensions, for example, by lithography, are strongly limited in size due to disadvantageous scaling. We use three-dimensional (3D)

Integrated-optic cavity resonators, such as Fabry–Perot microcavities and microrings, are key building blocks of photonics integrated circuits and are used extensively in applications such as optical communications and microwave photonics. For a single, conventional, optical-cavity resonator, resonance peaks appear periodically in frequency and have Lorentzian shapes in nature, which generally cannot

The measurement and stabilization of the carrier–envelope offset frequency ${f_{{\rm CEO}}}$ via self-referencing is paramount for optical frequency comb generation, which has revolutionized precision frequency metrology, spectroscopy, and optical clocks. Over the past decade, the development of chip-scale platforms has enabled compact integrated waveguides for supercontinuum generation. However, there

Optical phased arrays (OPAs) implemented in integrated photonic circuits could enable a variety of 3D sensing, imaging, illumination, and ranging applications, and their convergence in new lidar technology. However, current integrated OPA approaches do not scale—in control complexity, power consumption, or optical efficiency—to the large aperture sizes needed to support medium- to long-range lidar

Compact and powerful ultrafast light sources at high pulse repetition rates, based on mode-locked near infrared fiber lasers, are now widely available and are being used in applications such as frequency metrology, molecular spectroscopy, and laser micro-machining. The realization of such lasers in the mid-infrared has, however, remained a challenge for many years. Here we report a record-breaking

Plasmonic lasers suffer from low output power and divergent beams due to their subwavelength metallic cavities. We developed a phase-locking scheme for such lasers to significantly enhance their radiative efficiency and beam quality. An array of metallic microcavities is longitudinally coupled through traveling plasmon waves, which leads to radiation in a single spectral mode and a diffraction limited

Resonant optical antennas provide unprecedented opportunities to control light on length scales far below the diffraction limit. Recent studies have demonstrated that nanostructures made of multilayer transition metal dichalcogenides (TMDCs) can exhibit well-defined and intense Mie resonances in the visible to the near-infrared spectral range. These resonances are realizable because the TMDC materials

The development of ultrahigh-quality-factor ($\textit{Q}$) microresonators has been driving such technologies as cavity quantum electrodynamics (QED), high-precision sensing, optomechanics, and optical frequency comb generation. Here we report ultrahigh $Q$ crystalline microresonator fabrication with a $\textit{Q}$ exceeding ${10^8}$, for the first time to our knowledge, achieved solely by computer-controlled

In standard lasers, light amplification requires population inversion between an upper and a lower state to break the reciprocity between absorption and stimulated emission. However, in a medium prepared in a specific superposition state, quantum interference may fully suppress absorption while leaving stimulated emission intact, opening the possibility of lasing without inversion. Here we show that

Optical metamaterials are building blocks for the control of light behaviors and designs of photonic devices, where the inner interfaces in deep-subwavelength features are expected to have little impact on light transport, based on the concept of homogenization. Here we theoretically and experimentally study a new type of photonic interface (namely a hyperinterface) inside an optical metamaterial made

Waves typically propagate very differently through a homogeneous medium like free space than through an inhomogeneous medium like a complex dielectric structure. Here we present the surprising result that wave solutions in two-dimensional free space can be mapped to a solution inside a suitably designed non-Hermitian potential landscape such that both solutions share the same spatial distribution of

Surface plasmon mediated hot-carrier generation is utilized widely for the manipulation of electron–photon interactions in many types of optoelectronic devices including solar cells, photodiodes, and optical modulators. A diversity of plasmonic systems such as nanoparticles, resonators, and waveguides has been introduced to enhance hot-carrier generation; however, the impact of propagating surface

Metalenses have shown great promise in their ability to function as ultracompact optical systems for focusing and imaging. Remarkably, several designs have been recently demonstrated that operate over a large range of frequencies with minimized chromatic aberrations, potentially paving the way for ultrathin achromatic optics. Here, we derive fundamental bandwidth limits that apply to broadband optical

Strain engineering is a natural route to control the electronic and optical properties of two-dimensional (2D) materials. Recently, 2D semiconductors have also been demonstrated as an intriguing host of strain-induced quantum-confined emitters with unique valley properties inherited from the host semiconductor. Here, we study the continuous and reversible tuning of the light emitted by such localized

Quantum walks on graphs play an important role in the field of quantum algorithms. Fast hitting is one of the properties that quantum walk algorithms can utilize to outperform classical random walk algorithms. Fast hitting refers to a particle starting from the entrance node on a graph and trying to hit the exit node quickly. Especially, continuous-time quantum walks on random glued binary trees have

Quantum correlation is a fundamental resource for various quantum information tasks. It is thus of importance to share the correlation to utilize it for many parties, but sharing quantum correlation among multiple parties is strictly restricted by the well-known monogamy relations. Nonetheless, this restriction can be relaxed when weak measurements are employed. Here, we experimentally demonstrate

The generation of non-Gaussian quantum states of macroscopic mechanical objects is key to a number of challenges in quantum information science, ranging from fundamental tests of decoherence to quantum communication and sensing. Heralded generation of single-phonon states of mechanical motion is an attractive way toward this goal, as it is, in principle, not limited by the object size. Here we demonstrate

X-ray single-particle imaging involves the measurement of a large number of noisy diffraction patterns of isolated objects in random orientations. The missing information about these patterns is then computationally recovered in order to obtain the 3D structure of the particle. While the method has promised to deliver room-temperature structures at near-atomic resolution, there have been significant

Conventional computing architectures have no known efficient algorithms for combinatorial optimization tasks such as the Ising problem, which requires finding the ground state spin configuration of an arbitrary Ising graph. Physical Ising machines have recently been developed as an alternative to conventional exact and heuristic solvers; however, these machines typically suffer from decreased ground

Multi-port beam splitters are cornerstone devices for high-dimensional quantum information tasks, which can outperform the two-dimensional ones. Nonetheless, the fabrication of such devices has proven to be challenging with progress only recently achieved with the advent of integrated photonics. Here, we report on the production of high-quality $N \times N$ (with $N = 4,7$) multi-port beam splitters

Passive microwave imaging of incoherent sources is often approached in a lensless configuration through array-based interferometric processing. We present an alternative route in the form of a coded aperture realized using a dynamic metasurface. We demonstrate that this device can achieve an estimate of the spectral source distribution from a series of single-port spectral magnitude measurements and

In terahertz (THz) photonics, there is an ongoing effort to develop thin, compact devices such as dielectric photonic crystal (PhC) slabs with desirable light–matter interactions. However, previous works in THz PhC slabs have been limited to rigid substrates with thicknesses ${\sim}100\,\,{\rm s}$ of micrometers. Dielectric PhC slabs have been shown to possess in-plane modes that are excited by external

X-ray tomography is a powerful method for visualizing the three-dimensional structure of an object with a high spatial resolution. Conventional time-resolved x-ray tomography using synchrotron radiation requires fast rotation of the object, which limits the temporal resolution and hampers its application to, e.g., fluids and in vivo observation of living beings. Here, we present a multibeam x-ray optical

A critical component for all high-power laser systems that is particularly susceptible to laser damage is the antireflective coating, which maximizes energy transmission and minimizes scattered and stray light. We demonstrate the ability to generate substrate-engraved nanostructured surfaces (NS) for scalable and designable antireflective (AR) coatings that are monolithic to the substrate and can handle

Electro-optic quantum coherent interfaces map the amplitude and phase of a quantum signal directly to the phase or intensity of a probe beam. At terahertz frequencies, a fundamental challenge is not only to sense such weak signals (due to a weak coupling with a probe in the near-infrared) but also to resolve them in the time domain. Cavity confinement of both light fields can increase the interaction

Synthetic dimensions provide a promising platform for photonic quantum simulations. Manipulating the flow of photons in these dimensions requires an electric field. However, photons do not have charge and do not directly interact with electric fields. Therefore, alternative approaches are needed to realize electric fields in photonics. One approach is to use engineered gauge fields that can mimic the

Acoustic waves can serve as memory for optical information; however, propagating acoustic phonons in the gigahertz (GHz) regime decay on the nanosecond time scale. Usually this is dominated by intrinsic acoustic loss due to inelastic scattering of the acoustic waves and thermal phonons. Here we show a way to counteract the intrinsic acoustic decay of the phonons in a waveguide by resonantly reinforcing

Powerful ultrashort pulses in the deep-ultraviolet (deep-UV) are beneficial for diverse applications from fundamental science to industrial materials processing. However, reaching high powers via conventional approaches is challenging due to three central issues: dispersion, multiphoton absorption, and optical damage. Here, we simultaneously overcome these issues with a novel fifth-harmonic generation

All-dielectric metasurfaces comprising arrays of nanostructured high-refractive-index materials are re-imagining what is achievable in terms of the manipulation of light. However, the functionality of conventional dielectric-based metasurfaces is fixed by design; thus, their optical response is locked in at the fabrication stage. A far wider range of applications could be addressed if dynamic and reconfigurable

Quantum emitters coupled to plasmonic nanostructures can act as exceptionally bright sources of single photons, operating at room temperature. Plasmonic mode volumes supported by these nanostructures can be several orders of magnitude smaller than the cubic wavelength, which leads to dramatically enhanced light–matter interactions and drastically increased photon production rates. However, when increasing

Stimulated Raman spectroscopy has become a powerful tool to study the spatiodynamics of molecular bonds with high sensitivity, resolution, and speed. However, the sensitivity and speed of state-of-the-art stimulated Raman scattering spectroscopy are currently limited by the shot-noise of the light beam probing the Raman process. Here, we demonstrate in a proof-of-principle experiment an enhancement

Spin–orbit coupling of electromagnetic waves is one of the most important effects in topological photonics, but so far it has not been studied in photonic graphene implementations based on paraxial configuration, in particular, in atomic vapor cells. We generate experimentally a honeycomb refractive index pattern in such a cell using electromagnetically induced transparency. We demonstrate that an

Complete characterization of states and processes that occur within quantum devices is crucial for understanding and testing their potential to outperform classical technologies for communications and computing. However, solving this task with current state-of-the-art techniques becomes unwieldy for large and complex quantum systems. Here we realize and experimentally demonstrate a method for complete

Precise detection and monitoring of the frequency spectrum of microwave signals are essential to myriad scientific and technological disciplines, including both civil and defense areas, such as telecommunications, radar, biomedical instrumentation, radio astronomy, etc. Historically, microwave engineering has provided solutions for these tasks. However, current radio-frequency (RF) technologies suffer

Optical parametric oscillators (OPOs) are uniquely versatile—albeit complex—platforms for the generation of tunable coherent light in difficult-to-access spectral regions. A synchronously pumped ${\chi ^{(2)}}$ femtosecond OPO producing sub-100-fs pulses, by means of optical soliton formation in a single-mode fiber-feedback cavity, is presented for the first time. This approach removes the requirement

This erratum corrects a typographical error which appeared in Optica 7, 336 (2020). [CrossRef]

For sparse samples or in the presence of ambient light, the signal-to-noise ratio (SNR) performance of single-point-scanning coherent anti-Stokes Raman scattering (CARS) images is not optimized. As an improvement, we propose replacing the conventional CARS focus-point illumination with a periodically structured focus line while continuing to collect the transmitted CARS intensity on a single detector