Spin–orbit interaction (SOI) is a striking physical phenomenon in which spin and orbital features of a particle or a wave field affect each other. Recently, there has been significant interest in the SOI of light as it accompanies a number of fundamental light–matter interaction processes, enabling intriguing applications. We demonstrate the spin-orbit coupling between photons and phonons, in contrast

Cell-level quantitative features of retinal ganglion cells (GCs) are potentially important biomarkers for improved diagnosis and treatment monitoring of neurodegenerative diseases such as glaucoma, Parkinson’s disease, and Alzheimer’s disease. Yet, due to limited resolution, individual GCs cannot be visualized by commonly used ophthalmic imaging systems, including optical coherence tomography (OCT)

The arrayed waveguide grating (AWG) is a versatile and scalable passive photonic multiplexer that sees widespread usage. However, the necessity of a waveguide array engenders large device size, and gratings invariably commute finite power into undesired diffraction orders. Here, we demonstrate AWG-like functionality without a grating or waveguide array, yielding benefits to compactness, bandwidth,

Conventionally, time-dependent systems add energy to electromagnetic waves by parametric amplification. Here we identify a distinct, alternative mechanism—compression of lines of force.

Volumetric interrogation of the organization and processes of intracellular organelles and molecules in cellular systems with a high spatiotemporal resolution is essential for understanding cell physiology, development, and pathology. Here, we report high-resolution Fourier light-field microscopy (HR-FLFM) for fast and volumetric live-cell imaging. HR-FLFM transforms conventional cell microscopy and

Highly nonlinear optical materials with fast third-order nonlinear optical response are crucial for the operation of all-optical photonic devices, such as switches for signal processing and computation, power limiters, and saturable absorbers. The nonlinear response of traditional optical materials is weak, thus requiring large light intensities to induce significant changes in their properties. Here

A spatiotemporal optical vortex (STOV) is an intrinsic optical orbital angular momentum (OAM) structure in which the OAM vector is orthogonal to the propagation direction [Optica 6, 1547 (2019) [CrossRef] ] and the optical phase circulates in space-time. Here, we experimentally and theoretically demonstrate the generation of the second harmonic of a STOV-carrying pulse along with the conservation of

We report a 1310 nm heterogeneous quantum-dot distributed feedback laser on silicon with high efficiency and modulation capability and demonstrate isolator-free external modulation at 25 Gb/s using a metal-oxide semiconductor capacitor microring modulator.

The electric field waveform of a light field can be used to unlock a detailed recording of its interaction with matter, but accessing it requires a measurement with subfemtosecond temporal resolution. We demonstrate nonlinear photoconductive sampling of light fields at optical frequencies in ambient air. The resulting detection method provides broadband electric field measurement in an inexpensive

Light is critical for art. It allows us to see color, and can itself be a tool for creating unique pieces of art and design. Here we demonstrate that a laser can be a multifunctional and effective tool for the creation of masterpieces, analogous to the process of an artist creating a canvas with classical paints and brushes. We investigate the interaction between focused laser irradiation and metallic

Terahertz technology offers solutions in nondestructive testing and spectroscopy for many scientific and industrial applications. While direct detection of photons in this frequency range is difficult to achieve, quantum optics provides a highly attractive alternative: it enables the characterization of materials in hardly accessible spectral ranges by measuring easily detectable photons of a different

Wavefront shaping holds great potential for high-resolution imaging or light delivery either through or deep inside living tissue. However, one of the biggest barriers that must be overcome to unleash the full potential of wavefront shaping for practical biomedical applications is the fact that wavefront shaping, especially based on iterative feedback, requires lengthy measurements to obtain useful

Stimulated emission depletion (STED) microscopy enables the three-dimensional (3D) visualization of dynamic nanoscale structures in living cells, offering unique insights into their organization. However, 3D-STED imaging deep inside biological tissue is obstructed by optical aberrations and light scattering. We present a STED system that overcomes these challenges. Through the combination of two-photon

In order to efficiently image a non-absorbing sample (a phase object), dedicated phase contrast optics are required. Typically, these optics are designed with the assumption that the sample is weakly scattering, implying a linear relation between a sample’s phase and its transmission function. In the strongly scattering, nonlinear case, the standard optics are ineffective, and the transfer functions

A well-characterized wavefront is important for many x-ray free-electron laser (XFEL) experiments, especially for single-particle imaging (SPI), where individual biomolecules randomly sample a nanometer region of highly focused femtosecond pulses. We demonstrate high-resolution multiple-plane wavefront imaging of an ensemble of XFEL pulses, focused by Kirkpatrick–Baez mirrors, based on mixed-state

Since the advent of the laser, acousto-optic modulators have been an important tool for controlling light. Recent advances in on-chip lithium niobate waveguide technology present new opportunities for these devices. We demonstrate a collinear acousto-optic modulator in a suspended film of lithium niobate employing a high-confinement, wavelength-scale waveguide. By strongly confining the optical and

Electro-optic (EO) modulators rely on the interaction of optical and electrical signals with second-order nonlinear media. For the optical signal, this interaction can be strongly enhanced using dielectric slot–waveguide structures that exploit a field discontinuity at the interface between a high-index waveguide core and the low-index EO cladding. In contrast to this, the electrical signal is usually

Materials with strong second-order (${\chi ^{\!(2)}}$) optical nonlinearity, especially lithium niobate, play a critical role in building optical parametric oscillators (OPOs). However, chip-scale integration of low-loss ${\chi ^{\!(2)}}$ materials remains challenging and limits the threshold power of on-chip ${\chi ^{\!(2)}}$ OPO. Here we report an on-chip lithium niobate optical parametric oscillator

Optical frequency combs based on mode-locked lasers have revolutionized many areas of science and technology, such as precision metrology, optical frequency synthesis, and telecommunications. In recent years, a particular kind of frequency comb has been observed in edge-emitting semiconductor lasers where the phase difference between longitudinal laser modes is fixed but not zero. This results in a

Optical resonances in nanostructures can be harnessed to produce a wide range of structural colors. Conversely, the analysis of structural colors has been used to clarify the nature of optical resonances. Here, we show that silicon nanowire (NW) pairs can display a wide range of structural colors by controlling their radiative coupling. This is accomplished by exciting a series of Fabry–Pérot-like

Microwave-based satellite–ground links are used to transfer time and frequency in various applications such as metrology, navigation, positioning, and very long baseline interferometers. The existing approaches, however, cannot fully satisfy the requirements of these applications. In this study, we investigated the possibility of an optical-based satellite–ground link, where the transferred carriers

Photoacoustic spectroscopy, a powerful tool for gas analysis, typically uses bulky gas cells and discrete microphones. Here we exploit light-gas-acoustic interaction in a gas-filled anti-resonant hollow-core-fiber (AR-HCF) to demonstrate photoacoustic Brillouin spectroscopy (PABS). Pump absorption of gas molecules excites the acoustic resonances of the fiber, which modulates the phase of a probe beam

We present a unified and extended perspective of Bessel beams, irrespective of their orbital angular momentum (OAM)—zero, integer or noninteger—and mode—scalar or vectorial, and LSE/LSM or TE/TM in the latter case. The unification is based on the integral superposition of constituent waves along the angular-spectrum cone of the beam, and enables us to describe, compute, relate, and implement all Bessel

Conventional chiral metalenses based on helicoidal structures suffer from low energy efficiency and fixed chirality due to the extremely low conversion efficiency of cross-circular polarization in helicity-matched structures. Here, we report on high-efficiency and chirality-reversible metalens imaging using nested dual helical surfaces. The high-efficiency chiral metalenses were implemented by splitting

Surface polaritons display short wavelengths compared to propagating light, thus enabling large spatial concentration and enhancement of electromagnetic energy. However, this wavelength mismatch is generally accompanied by poor light-to-polariton coupling that limits potential applications in areas such as optical sensing and optoelectronics. Here, we address this problem by demonstrating that a small

Non-Hermitian systems have recently attracted significant attention in photonics. One of the hallmarks of these systems is the possibility of realizing asymmetric mode-switching and omni-polarizer action through the dynamic encirclement of exceptional points (EPs). Here, we offer a new perspective on the operating principle of these devices, and we theoretically and experimentally show that linear

Polarization engineering and characterization of coherent high-frequency radiation are essential to investigate and control the symmetry properties of light–matter interaction phenomena at their most fundamental scales. This work demonstrates that polarization control and characterization of high-harmonic generation provides an excellent ellipsometry tool that can fully retrieve both the amplitude

Recent advances in ultrafast extreme ultraviolet (EUV) and x-ray light sources provide direct access to fundamental time and length scales for biology, chemistry, and materials physics. However, such light pulses are challenging to measure due to the need for femtosecond time resolution at difficult-to-detect wavelengths. Also, single-shot measurements are needed because severe pulse-to-pulse fluctuations

Future PHz electronic devices may be able to perform operations on few-femtosecond time-scales. Such devices are based on the ability to control currents induced by intense few-cycle laser pulses. Investigations of this control scheme have been based on complex, amplified laser systems, typically delivering mJ or sub-mJ-level laser pulses, limiting the achievable clock rate to the kHz regime. Here

Nonlinear photonic crystals are microstructures with quadratic nonlinearity (${\chi ^{(2)}}$) that have been extensively used for the generation and control of coherent light at new frequencies. Thanks to the recent invention of 3D ${\chi ^{(2)}}$-nonlinearity engineering techniques using femtosecond laser pulses, studies of intense light interaction with 3D nonlinear photonic crystals are now experimentally

Flexible grid wavelength division multiplexing is a powerful tool in lightwave communications to maximize spectral efficiency. In the emerging field of quantum networking, the need for effective resource provisioning is particularly acute, given the generally lower power levels, higher sensitivity to loss, and inapplicability of optical detection and retransmission. In this letter, we leverage flex

So far, it has been assumed that selective excitation of a desired valley in the Brillouin zone of a hexagonal two-dimensional material has to rely on using circularly polarized fields. We theoretically demonstrate a way to control the valley excitation in hexagonal 2D materials on a few-femtosecond timescale using a few-cycle, linearly polarized pulse with controlled carrier–envelope phase. The valley

Adaptive optics scanning light ophthalmoscopy (AOSLO) allows non-invasive visualization of the living human eye at the microscopic scale; but even with correction of the ocular wavefront aberrations over a large pupil, the smallest cells in the photoreceptor mosaic cannot always be resolved. Here, we synergistically combine annular pupil illumination with sub-Airy disk confocal detection to demonstrate

Quantum imaging using photon pairs with strong quantum correlations has been harnessed to bring quantum advantages to various fields from biological imaging to range finding. Such inherent non-classical properties support the extraction of more valid signals to build photon-limited images, even in low-light conditions where the shot noise becomes dominant as light decreases to a single-photon level

Long-range active imaging has widespread applications in remote sensing and target recognition. Single-photon light detection and ranging (lidar) has been shown to have high sensitivity and temporal resolution. On the application front, however, the operating range of practical single-photon lidar systems is limited to about tens of kilometers over the Earth’s atmosphere, mainly due to the weak echo

Large-volumetric optical tomography with molecular specificity has long been pursued to tackle the challenge of dissecting both structural and chemical organization of complicated biological tissues. Here, based on counterpropagating femtosecond pulse laser trains and stimulated Raman scattering, we report pulse-sheet chemical tomography (PCT), which allows label-free bond-selective three-dimensional

Polarization of light has been widely used as a contrast mechanism in two-dimensional (2D) microscopy and also in some three-dimensional (3D) imaging modalities. In this paper, we report the 3D tomographic reconstruction of the refractive index (RI) tensor using 2D scattered fields measured for different illumination angles and polarizations. Conventional optical diffraction tomography (ODT) has been

Electro-optic modulators with low voltages and large bandwidths are crucial for both analog and digital communication. Recently, thin-film lithium niobate modulators have emerged as a strong candidate for next generation electro-optic solutions. These modulators offer significantly improved voltage–bandwidth performances over the existing bulk lithium niobate modulators while preserving key material

Since its advent in the 1970s, optical tweezers have been widely deployed as a preferred non-contact technique for manipulating microscale objects. On-chip integrated optical tweezers, which afford significant size, weight, and cost benefits, have been implemented, relying upon near-field evanescent waves. As a result, these tweezers are only capable of manipulation in near-surface regions and often

The existence of quantized vortices is a key feature of Bose–Einstein condensates. In equilibrium condensates, only quantum vortices of unit topological charge are stable, due to the dynamical instabilities of multiply charged defects, unless supported by strong external rotation. Due to immense interest in the physics of these topological excitations, a great deal of work has been done to understand

We present an approach for generating widely separated first sidebands based solely on the four-wave-mixing process in optical parametric oscillators built on complementary metal–oxide–semiconductor-compatible photonic chips. Using higher-order transverse modes to perform dispersion engineering, we obtain zero-group-velocity dispersion near 796 nm. By pumping the chip in the normal dispersion region

Wave mixing is an archetypical phenomenon in bosonic systems. In optomechanics, the bidirectional conversion between electromagnetic waves or photons at optical frequencies and elastic waves or phonons at radio frequencies is building on precisely this fundamental principle. Surface acoustic waves (SAWs) provide a versatile interconnect on a chip and thus enable the optomechanical control of remote

Acceleration measurement is widely used in commercial, scientific, and defense applications, but the resolution and accuracy achievable for demanding applications is limited by the current technology used to build and calibrate accelerometers. We report an optomechanical accelerometer based on a Fabry–Perot microcavity in a silicon chip that is extremely precise, field deployable, and can self-calibrate

Distributed measurement of forward stimulated Brillouin scattering (FSBS) attracted substantial attention for its ability to probe media surrounding optical fibers. Currently, all techniques extract the information from the FSBS-induced local energy transfer among distinct optical tones, this transfer being fundamentally sensitive to intensity perturbations imposed by nonlinear effects. Instead, here

Manipulating the polarization orientation of light is essential in modern optics, biology, and related fields, but the strong optical dispersion inherent in current polarization rotators severely restricts their use to single-frequency lasers and their flexibility in system design. Many attempts have been made to realize dispersionless polarization rotation, usually by designing a complex set of wave

We propose and fully analyze the simplest technique to date (to our knowledge) for generating light-based universal quantum computing resources, namely, 2D, 3D, and $n$-hypercubic cluster states in general. The technique uses two standard optical components: first, a single optical parametric oscillator pumped below threshold by a monochromatic field, which generates Einstein–Podolsky–Rosen entangled

Engineered non-Hermitian systems featuring exceptional points (EPs) can lead to a host of extraordinary phenomena in diverse fields ranging from photonics, acoustics, opto-mechanics, and electronics to atomic physics. In optics, non-Hermitian dynamics are typically realized using dissipation and phase-insensitive gain accompanied by unavoidable fluctuations. Here, we introduce non-Hermitian dynamics

Extremely nonlinear spectroscopy based on high-order-harmonic generation has become a powerful investigation method for attosecond dynamics in gas and solid targets. In particular, the phase of harmonic emission was shown to carry profound insight into atomic and molecular structure and dynamics. However, current techniques offer phase measurements only along specific directions, thus providing partial

A dielectric material’s response to light is microscopically defined by field-cycle-driven motion of electron densities in the restoring forces of the atomic environment. Here we apply single-cycle mid-infrared pulses to drive the nonlinear motion of valence electrons in a heteronuclear crystal with asymmetric structure and report how the macroscopic optical response can be tracked back to the real-space

Electrons in two-dimensional hexagonal materials have an extra degree of freedom, the valley pseudospin, that can be used to encode and process quantum information. Valley-selective excitations, governed by the circularly polarized light resonant with the material’s bandgap, are the foundation of valleytronics. It is often assumed that achieving valley selective excitation in pristine graphene with

In the last 10 years, freeform optics has enabled compact and high-performance imaging systems. This article begins with a brief history of freeform optics, focusing on imaging systems, including marketplace emergence. The development of this technology is motivated by the clear opportunity to enable science across a wide range of applications, spanning from extreme ultraviolet lithography to space

The elastic backscattering of light in optical fiber is a fundamental phenomenon that sets the ultimate performance of several fiber systems such as gyroscopes and bidirectional transfer links. Until now, efforts to reduce the backscattering coefficient have yielded limited results, with the lowest value sitting at around ${-}{{76}}\;{\rm{dB/m}}$ in Ge-free silica-core fiber at 1.55 µm. Here, we present

We introduce Michelson holography (MH), a holographic display technology that optimizes image quality for emerging holographic near-eye displays. Using two spatial light modulators (SLMs), MH is capable of leveraging destructive interference to optically cancel out undiffracted light corrupting the observed image. We calibrate this system using emerging camera-in-the-loop holography techniques and

Coded-aperture light field (CALF) imaging can record four-dimensional information of incident light rays with a high angular resolution while retaining a camera’s full pixel count. However, existing systems are limited by either imaging speeds and image contrasts of liquid-crystal spatial light modulators or by severe dispersion to broadband light of digital micromirror devices (DMDs), both of which

White-light continuum (WLC) generation in bulk media finds numerous applications in ultrafast optics and spectroscopy. Due to the complexity of the underlying spatiotemporal dynamics, WLC optimization typically follows empirical procedures. Deep reinforcement learning (RL) is a branch of machine learning dealing with the control of automated systems using deep neural networks. In this Letter, we demonstrate

Speckle patterns have been used widely in imaging techniques such as ghost imaging, dynamic speckle illumination microscopy, structured illumination microscopy, and photoacoustic fluctuation imaging. Recent advances in the ability to control the statistical properties of speckles has enabled the customization of speckle patterns for specific imaging applications. In this work, we design and create

Scientific and technological progress depend substantially on the ability to image on the nanoscale. In order to investigate complex, functional, nanoscopic structures like, e.g., semiconductor devices, multilayer optics, or stacks of 2D materials, the imaging techniques not only have to provide images but should also provide quantitative information. We report the material-specific characterization

Random lasers (RLs) rely on light amplification in a gain material with feedback from multiple scattering in disordered media. They are unconventional light sources characterized by multiple narrow peaks emission with high potential in imaging and sensing applications. At variance with ordinary lasers, optical interaction between single RLs arranged in networks of multiply interconnected resonators

Controlling gain and loss of coupled optical cavities can induce non-Hermitian degeneracies of eigenstates, called exceptional points (EPs). Various unconventional phenomena around EPs have been reported, and are expected to incorporate extra functionalities into photonic devices. The eigenmode exactly under EP degeneracy is also predicted to exhibit enhanced radiation. However, such responses have

Despite recent progress in nonlinear optics in wavelength-scale resonators, there are still open questions on the possibility of parametric oscillation in such resonators. We present a general approach to predict the behavior and estimate the oscillation threshold of multi-mode subwavelength and wavelength-scale optical parametric oscillators (OPOs). As an example, we propose an OPO based on Mie-type