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

Diffractive optics can be used to accurately control optical wavefronts, even in situations where refractive components such as lenses are not available. For instance, conventional Fresnel zone plates (ZPs) enable focusing of monochromatic radiation. However, they lead to strong chromatic aberrations in multicolor operation. In this work, we propose the concept of spatial entropy minimization as a

We perform resonant spectroscopy of erbium implanted into nanophotonic silicon waveguides, finding 1 GHz inhomogeneous broadening and homogeneous linewidths below 0.1 GHz. Our study thus introduces a promising materials platform for on-chip quantum information processing.

Optical tweezers are a powerful tool to hold and manipulate particles on the microscale. The ability to measure tiny forces enables detailed investigations, e.g., of the mechanical properties of biological systems. Here we present a generally applicable method to simultaneously measure all components of the force applied to a specific particle in a trapped ensemble, or to a specific site of an extended

Single particle imaging at x-ray free electron lasers (XFELs) has the potential to determine the structure and dynamics of single biomolecules at room temperature. Two major hurdles have prevented this potential from being reached, namely, the collection of sufficient high-quality diffraction patterns and robust computational purification to overcome structural heterogeneity. We report the breaking

Three-dimensional (3D) refractive index (RI) tomography has recently become an exciting new tool for biological studies. However, its limitation to (1) thin samples resulting from a need of transmissive illumination and (2) small fields of view (typically ${\sim}50 \;{\unicode{x00B5}{\rm m}} \times 50 \;{\unicode{x00B5}{\rm m}}$) has hindered its utility in broader biomedical applications. In this

In time-correlated single-photon counting (TCSPC), photons that arrive during the detector and timing electronics dead times are missed, causing distortion of the detection time distribution. Conventional wisdom holds that TCSPC should be performed with detections in fewer than 5% of illumination cycles to avoid substantial distortion. This requires attenuation and leads to longer acquisition times

Electron microscopes provide a powerful platform for exploring physical phenomena with nanoscale resolution, based on the interaction of free electrons with the excitations of a sample such as phonons, excitons, bulk plasmons, and surface plasmons. The interaction usually results in the absorption or emission of such excitations, which can be detected directly through cathodoluminescence or indirectly

For measurements designed to accurately determine layer thickness, there is a natural trade-off between sensitivity to optical thickness and lateral resolution due to the angular ray distribution required for a focused beam. We demonstrate a near-field imaging approach that enables subwavelength lateral resolution in images with contrast dependent on optical thickness. We illuminate a sample in a total

In order to build nanophotonic devices, it is important to understand and ultimately control the optical mode structure within potential components such as nanoscale waveguides. However, experimental characterization of such modes in the optical regime is difficult due to the nanoscale dimensions of such components and the perturbations that would be induced by a near-field probe. Here, we demonstrate

Artificial lattices of coherently coupled macroscopic states are at the heart of applications ranging from solving hard combinatorial optimization problems to simulating complex many-body physical systems. The size and complexity of the problems scale with the extent of coherence across the lattice. Although the fundamental limit of spatial coherence depends on the nature of the couplings and lattice

Wave absorption in time-invariant, passive thin films is fundamentally limited by a trade-off between bandwidth and overall thickness. In this work, we investigate the use of temporal switching to reduce signal reflections from a thin grounded slab over broader bandwidths. We extend quasi-normal mode theory to time switching, developing an ab initio formalism that can model a broad class of time-switched

The robust spin and momentum valley locking of electrons in two-dimensional semiconductors makes the valley degree of freedom of great utility for functional optoelectronic devices. Owing to the difference in optical selection rules for the different valleys, these valley electrons can be addressed optically. The electrons and excitons in these materials exhibit the valley Hall effect, where the carriers

Solid-state single-photon emitters (SPEs) such as the bright, stable, room-temperature defects within hexagonal boron nitride (hBN) are of increasing interest for quantum information science. To date, the atomic and electronic origins of SPEs within hBN have not been well understood, and no studies have reported photochromism or explored cross correlations between hBN SPEs. Here, we combine irradiation

An atomic system that can be addressed via a single optical mode, hereafter called a one-dimensional atom, is central for many applications in optical quantum technologies. A cavity with a large Purcell factor is required to collect the emission efficiently, but a small Purcell factor is required for long-time memory storage. Here, we introduce an effective and versatile one-dimensional atom consisting

Quantum networks will enable a variety of applications, from secure communication and precision measurements to distributed quantum computing. Storing photonic qubits and controlling their frequency, bandwidth, and retrieval time are important functionalities in future optical quantum networks. Here we demonstrate these functions using an ensemble of erbium ions in yttrium orthosilicate coupled to

Radially polarized lasers, in contrast to the conventional Gaussian laser mode, possess unique features such as sharp focusing and strong longitudinal fields. Thus far, radially polarized femtosecond pulses have been produced only by low-power devices such as mode-locked resonators and segmented half-wave plates. It is imperative to solve the bottleneck problem in generating higher powers and shorter

High-brilliance synchrotron radiation sources have opened new avenues for x-ray polarization analysis that go far beyond conventional polarimetry in the optical domain. With linear x-ray polarizers in a crossed setting, polarization extinction ratios down to ${{10}^{- 10}}$ can be achieved. This renders the method sensitive to probe the tiniest optical anisotropies that would occur, for example, in

Machine intelligence has become a driving factor in modern society. However, its demand outpaces the underlying electronic technology due to limitations given by fundamental physics, such as capacitive charging of wires, but also by system architecture of storing and handling data, both driving recent trends toward processor heterogeneity. Task-specific accelerators based on free-space optics bear

In vivo imaging of small animals is of wide interest to the biomedical community studying biological disease and developmental processes. However, optical imaging deep in tissue is severely limited by light scattering, posing restrictions on the imaging depth, image contrast, and spatial resolution. We demonstrate optical coherence projection tomography (OCPT) as a fast three-dimensional optical imaging

Unconventional systems that adopt the concept of ghost schemes have led to advancements in some imaging applications. However, their application in quantitative phase imaging remains a challenge. Here, we introduce a basis for quantitative phase imaging with ghost diffraction and demonstrate ghost diffraction holographic microscopy for complex-valued imaging. We achieve this by introducing an off-axis

The absence of the single-photon nonlinearity has been a major roadblock in developing quantum photonic circuits at optical frequencies. In this paper, we demonstrate a periodically poled thin film lithium niobate microring resonator (PPLNMR) that reaches 5,000,000%/W second-harmonic conversion efficiency—almost 20-fold enhancement over the state-of-the-art—by accessing its largest ${\chi ^{(2)}}$

In many laser systems, frequency combs whose output is frequency-modulated (FM) can form, producing light whose frequency sweeps linearly. While this intriguing result has been replicated experimentally and numerically, a compact description of the core physics has remained elusive. By creating a mean-field theory for active cavities analogous to the Lugiato–Lefever equation, we show that these lasers

Topological photonic interfaces support topologically nontrivial optical modes with helical character. When combined with an embedded quantum emitter that has a circularly polarized transition dipole moment, a chiral quantum optical interface is formed due to spin-momentum locking. Here, we experimentally realize such an interface by integrating semiconductor quantum dots into a valley-Hall topological

Modern nanophotonic and meta-optical devices utilize a tremendous number of structural degrees of freedom to enhance light–matter interactions. A fundamental question is how large such enhancements can be. We develop an analytical framework to derive upper bounds to single-frequency electromagnetic response, across near- and far-field regimes, for any materials, naturally incorporating the tandem effects

Maskless photolithography based on digital micromirror devices (DMDs) is considered the next-generation low-cost lithographic technology. However, DMD-based digital photolithography has been implemented only for micrometer-scale pattern generation, whereas sophisticated photonic devices require feature sizes of approximately 100 nm. In this study, we adopt a high-magnification objective lens (${200}

Solid-state defect qubit systems with spin-photon interfaces show great promise for quantum information and metrology applications. Photon collection efficiency, however, presents a major challenge for defect qubits in high refractive index host materials. Inverse-design optimization of photonic devices enables unprecedented flexibility in tailoring critical parameters of a spin-photon interface including

Optical parametric oscillations (OPOs)—the nonlinear coherent coupling of an optically excited two-particle pump state to signal and idler states correlated in energy—is relevant for optical amplification and generation of correlated photons. OPOs require states with well-defined symmetries and energies; the fine-tuning of material properties and structural dimensions remains a challenge for the realization

The dark solitons observed in a large variety of nonlinear media are unstable against the modulational (snake) instabilities and can break in vortex streets. This behavior has been investigated in nonlinear optical crystals and ultra-cold atomic gases. However, a deep characterization of this phenomenon is still missing. In a resonantly pumped two-dimensional polariton superfluid, we use an all-optical

Nonlinear propagation of signals in single-mode fibers is well understood, and is typically observed by measuring the temporal profile or optical spectrum of an emerging signal. In multimode fibers, the nonlinearity has both a spatial and a temporal element, and a complete investigation of the interactions between propagating modes requires resolving the output in both space and time. We report here

The optoelectronic properties of asymmetric metal nanostructures are of current interest for applications in photonics, sensing, and catalysis. Here, we break the symmetry of the localized surface plasmon resonance of gold nanorods by selective overgrowth of a single tip via a high-yield (${\gt}{80}\%$) wet-chemical method. While optical spectroscopy exhibits a bathochromic shift of the nanoparticle

Three-dimensional (3D) positioning with the correction of imaging aberrations in the photonic platform remains challenging. Here, we combine techniques from nanophotonics and machine vision to significantly improve the imaging and positioning performance. We use a titanium dioxide metalens array operating in the visible region to realize multipole imaging and introduce a cross-correlation-based gradient

Phase singularities are seen in optical vortex beams, which are located in a two-dimensional spatial plane. Phase singularities in optical spectra are not common, but exploiting the extreme phase behavior around the singularity point could improve conventional optical devices for molecular-/bio-sensing, large phase modulation, etc. Recently, spectral phase singularities have been reported in reflection-type

We report the theoretical prediction and experimental realization of the optical phenomenon of “ballistic resonance.” This resonance, resulting from the interplay between free charge motion in confining geometries and periodic driving electromagnetic fields, can be utilized to achieve negative permittivity at frequencies well above the bulk plasma frequency. As a proof of principle, we demonstrate

Superconducting nanowire single-photon detectors (SNSPDs) are an enabling technology for myriad quantum-optics experiments that require high-efficiency detection, large count rates, and precise timing resolution. The system detection efficiencies (SDEs) for fiber-coupled SNSPDs have fallen short of theoretical predictions of near unity by at least 7%, with the discrepancy being attributed to scattering

Linking superconducting quantum devices to optical fibers via microwave-optical quantum transducers may enable large-scale quantum networks. For this application, transducers based on the Pockels electro-optic (EO) effect are promising for their direct conversion mechanism, high bandwidth, and potential for low-noise operation. However, previously demonstrated EO transducers require large optical pump

Mid-infrared (mid-IR) light scatters much less than shorter wavelengths, allowing greatly enhanced penetration depths for optical imaging techniques such as optical coherence tomography (OCT). However, both detection and broadband sources in the mid-IR are technologically challenging. Interfering entangled photons in a nonlinear interferometer enables sensing with undetected photons, making mid-IR

Quantum networks are likely to have a profound impact on the way we compute and communicate in the future. In order to wire together superconducting quantum processors over kilometer-scale distances, we need transducers that can generate entanglement between the microwave and optical domains with high fidelity. We present an integrated electro-optic transducer that combines low-loss lithium niobate

Amplified bursts of laser pulses are sought for various machining, deposition, spectroscopic, and strong-field applications. Standard frequency- and time-domain techniques for pulse division become inadequate when intraburst repetition rates reach the terahertz (THz) range as a consequence of inaccessible spectral resolution, requirement for interferometric stability, and collapse of the chirped-pulse

An intuitive and complete understanding of the underlying processes in high harmonic generation (HHG) in solids will enable the development and optimization of experimental techniques for attosecond measurement of dynamical and structural properties of solids. Here we introduce the Wannier quasi-classical (WQC) theory, which allows the characterization of HHG in terms of classical trajectories. The

Controlling the wave function of free electrons is important to improve the spatial resolution of electron microscopes, the efficiency of electron interaction with sample modes of interest, and our ability to probe ultrafast materials dynamics at the nanoscale. In this context, attosecond electron compression has been recently demonstrated through interaction with the near fields created by scattering

Corrections have been made to labels in Fig. 1(b) and Fig. 3 of Optica 7, 218 (2020) [CrossRef] .

This erratum to Optica 7, 820 (2020) [CrossRef] clarifies the origins of the supplementary material.

In vivo imaging of small animals is of wide interest to the biomedical community studying biological disease and developmental processes. However, optical imaging deep in tissue is severely limited by light scattering, posing restrictions on the imaging depth, image contrast, and spatial resolution. We demonstrate optical coherence projection tomography (OCPT) as a fast three-dimensional optical imaging

Unconventional systems that adopt the concept of ghost schemes have led to advancements in some imaging applications. However, their application in quantitative phase imaging remains a challenge. Here, we introduce a basis for quantitative phase imaging with ghost diffraction and demonstrate ghost diffraction holographic microscopy for complex-valued imaging. We achieve this by introducing an off-axis

Topological photonic interfaces support topologically nontrivial optical modes with helical character. When combined with an embedded quantum emitter that has a circularly polarized transition dipole moment, a chiral quantum optical interface is formed due to spin-momentum locking. Here, we experimentally realize such an interface by integrating semiconductor quantum dots into a valley-Hall topological

We present design concepts for optical modulators without using any equalization or bespoke fabrication techniques. The demonstrated silicon photonics transmitter can operate at 100 Gbps OOK, while the power efficiency of the driver is 2.03 pJ/bit.

Wearable near-eye displays for virtual and augmented reality (VR/AR) have seen enormous growth in recent years. While researchers are exploiting a plethora of techniques to create life-like three-dimensional (3D) objects, there is a lack of awareness of the role of human perception in guiding the hardware development. An ultimate VR/AR headset must integrate the display, sensors, and processors in

Optical diffraction tomography (ODT) is an indispensable tool for studying objects in three dimensions. Until now, ODT has been limited to coherent light because spatial phase information is required to solve the inverse scattering problem. We introduce a method that enables ODT to be applied to imaging incoherent contrast mechanisms such as fluorescent emission. Our strategy mimics the coherent scattering

Compact, lightweight, high-power beam-steering devices operating in the mid-infrared atmospheric window $\lambda = {3\! -\! 5}\;\unicode{x00B5}{\rm m}$ are attractive for aerial-based applications such as long-range lidar and countermeasures. In the near-infrared spectral region, optical phased arrays (OPAs) have emerged as the dominant nonmechanical on-chip beam-steering technology, with a preponderance

The interactions of optical solitons in passively mode-locked lasers result in abundant bound states that reflect intriguing nonlinear attractor behaviors in complex dissipative systems. In this study, we tested the strength limits of the fixed-point attractors that govern bound soliton molecule formation in passively mode-locked lasers. To this end, we probed the relative timing jitter in a closely

Low-noise light sources are important for on-chip interconnects, sensors, and quantum technology. We show that, using novel cavity designs featuring deep sub-wavelength confinement, it is possible to strongly reduce quantum fluctuations over a large bandwidth. The results could enable integrated sources with extremely low amplitude noise.

Reconfigurable optical devices provide new opportunities for integrated photonics. The use of chalcogenide glasses, with large refractive index nonlinearity and photosensitivity, in conjunction with the microresonator platform has proven to be a powerful tool in the study and application of nanophotonics. Here, we report cavity-enhanced photo-induced writing and erasing of gratings in a chalcogenide

The availability of intense soft x-ray beams with tunable energy and polarization has pushed the development of highly sensitive, element-specific, and noninvasive microscopy techniques to investigate condensed matter with high spatial and temporal resolution. The short wavelengths of soft x-rays promise to reach spatial resolutions in the deep single-digit nanometer regime, providing unprecedented

Second-harmonic generation (SHG) microscopy is currently the preferred technique for visualizing collagen in intact tissues, but the usual implementations struggle to reveal collagen fibrils oriented out of the imaging plane. Recently, an advanced SHG modality, circular dichroism SHG (CD-SHG), has been proposed to specifically highlight out-of-plane fibrils. In this study, we present a theoretical

Photoacoustic fluctuation imaging, which exploits randomness in photoacoustic generation, provides enhanced images in terms of resolution and visibility, as compared to conventional photoacoustic images. While a few experimental demonstrations of photoacoustic fluctuation imaging have been reported, it has to date not been described theoretically. In the first part of this work, we propose a theory

The insensitivity of multiphoton microscopy to optical scattering enables high-resolution, high-contrast imaging deep into tissue, including in live animals. Scattering does, however, severely limit the use of spectral dispersion techniques to improve spectral resolution. In practice, this limited spectral resolution together with the need for multiple excitation wavelengths to excite different fluorophores

Optical waveguide segments based on geometrically unbound photonic crystal fiber (PCF) designs could be exploited as building blocks to realize miniaturized complex devices that implement advanced photonic operations. Here, we show how to fabricate optical waveguide segments with PCF designs by direct high-resolution 3D printing and how the combination of these segments can realize complex photonic

Optical microscopy has been an indispensable tool for studying complex biological systems, but is often hampered by problems of speed and complexity when performing 3D volumetric imaging. Here, we present a multifocus imaging strategy based on the use of a simple z-splitter prism that can be assembled from off-the-shelf components. Our technique enables a widefield image stack to be distributed onto

High-speed optical systems are revolutionizing biomedical imaging in microscopy, DNA sequencing, and flow cytometry, as well as numerous other applications, including data storage, display technologies, printing, and autonomous vehicles. These systems often achieve the necessary imaging or sensing speed through the use of resonant galvanometric optical scanners. Here, we show that the optical performance