The microfluidic-based, label-free image-guided cell sorter offers a low-cost, high information content, and disposable solution that overcomes many limitations in conventional cell sorters. However, flow confinement for most microfluidic devices is generally only one-dimensional using sheath flow. As a result, the equilibrium distribution of cells spreads beyond the focal plane of commonly used Gaussian

Near-field imaging techniques, at terahertz frequencies (1–10 THz), conventionally rely on bulky laser sources and detectors. Here, we employ a semiconductor heterostructure laser as a THz source and, simultaneously, as a phase-sensitive detector, exploiting optical feedback interferometry combined with scattering near-field nanoscopy. We analyze the amplitude and phase sensitivity of the proposed

We study the generation of harmonics from graphene under the influence of an artificial magnetic field, generated via bending of a graphene flake. We show how the Landau level structure induced by the pseudomagnetic field breaks the centrosymmetry of graphene, thus allowing the generation of even harmonics. We also show that depending on the impinging pulse duration, the nonlinear signal does not only

Driven by the increasing significance of artificial intelligence, the field of neuromorphic (brain-inspired) photonics is attracting increasing interest, promising new, high-speed, and energy-efficient computing hardware for key applications in information processing and computer vision. Widely available photonic devices, such as vertical-cavity surface emitting lasers (VCSELs), offer highly desirable

UV laser pulses at 266 nm with 170 ps duration and up to 300 mJ energy create UV filaments. The effects of different beam preparation scenarios on UV filamentation are discussed. Beam preparation by focusing in vacuum and launching into the atmosphere through an aerodynamic window establishes the existence of filaments as self-guided non-diffracting entities. In addition, focusing through the aerodynamic

Orbital angular momentum (OAM) modes, having unique properties of a helical phase structure and doughnut intensity profile, have been widely studied in fiber-optic communications, in terms of OAM modulation and OAM multiplexing. In general, different types of specialty fibers with a ring-shape structure are preferred for more stable OAM transmission, which, however, may face greater manufacturing challenge

Many bioimaging studies, including those in engineered tissue constructs, intravital microscopy in animal models, and medical imaging in humans, require cellular-resolution imaging of structures deep within a sample. Yet, many of the current approaches are limited in terms of resolution, but also in invasiveness, repeatable imaging of the same location, and accessible imaging depth. We coin the term

Microwave photonic approaches for the generation of microwave signals have attracted substantial attention in recent years, thanks to the significant advantages brought by photonics technology, such as high frequency, large bandwidth, and immunity to electromagnetic interference. An optoelectronic oscillator (OEO) is a paradigmatic microwave photonic oscillator that produces microwave signals with

Increasing demand for every faster information throughput is driving the emergence of integrated photonic technology. The traditional silicon platform used for integrated electronics cannot provide all of the functionality required for fully integrated photonic circuits, and thus, the last decade has seen a strong increase in research and development of hybrid and heterogeneous photonic integrated

Interfacing integrated on-chip waveguides with spectroscopic approaches represents one research direction within current photonics aiming at reducing geometric footprints and increasing device densities. Particularly relevant is to connect chip-integrated waveguides with established fiber-based circuitry, opening up the possibility for a new class of devices within the field of integrated photonics

Nucleic acids and proteins are the two most important target types used in molecular diagnostics. In many instances, simultaneous sensitive and accurate detection of both biomarkers from the same sample would be desirable, but standard detection methods are highly optimized for one type and not cross-compatible. Here, we report the simultaneous multiplexed detection of SARS-CoV-2 RNAs and antigens

Photo-mixing with its advantages of ultra-large bandwidth and precise tunability has emerged as an important technique for terahertz (THz) wave generation. Recently, graphene photodetectors exhibiting a large bandwidth are expected to further boost the development of integrated THz emitters. Here, we fabricate a sub-THz emitter based on a large-bandwidth silicon–plasmonic graphene (SPG) photodetector

Systems of coupled cavity modes have the potential to provide bright quantum optical states of light in a highly versatile manner. Microring resonators, for instance, are highly scalable candidates for photon sources. Thanks to CMOS fabrication techniques for their small footprint and the relative ease of coupling many such microrings together. However, surface roughness of the waveguides and defects

Near-field microscopy techniques operating in the terahertz (THz) frequency band offer the tantalizing possibility of visualizing with nanometric resolution the localized THz fields supported by individual resonators, micro-structured surfaces, and metamaterials. Such capabilities promise to underpin the future development and characterization of a wide range of devices, including THz emitters, detectors

We present a photonic approach for fast quantum random number generation based on optically sampled amplified spontaneous emission (ASE). This approach utilizes a terahertz optical asymmetric demultiplexer to sample the ASE and then digitize the sampled optical pulses into random bits using a multi-bit parallel comparator. A proof-of-concept experiment demonstrates that 40 Gb/s random bits with verified

Unlocking the true potential of optical spectroscopy on the nanoscale requires development of stable and low-noise laser sources. Here, we have developed a low-noise supercontinuum (SC) source based on an all-normal dispersion fiber pumped by a femtosecond fiber laser and demonstrate high resolution, spectrally resolved near-field measurements in the near-infrared (NIR) region. Specifically, we explore

Microscopes and various forms of interferometers have been used for decades in optical metrology of objects that are typically larger than the wavelength of light λ. Metrology of sub-wavelength objects, however, was deemed impossible due to the diffraction limit. We report the measurement of the physical size of sub-wavelength objects with deeply sub-wavelength accuracy by analyzing the diffraction

An optical pulse asymptotically reaching zero group velocity in tapered waveguides can ultimately stop at a certain position in the taper accompanied by a strong spatial compression. This phenomenon can also be observed in spatiotemporal systems where the pulse velocity asymptotically reaches the velocity of a tapered front. The first system is well known from tapered plasmonic waveguides where adiabatic

Quantum photonic circuits with integrated on-demand quantum emitters can act as building blocks for photonic gates and processors with enhanced quantum functionality. To scale up such quantum devices to larger and more powerful systems, eventually reaching the quantum advantage, the scalable integration of many emitters with identical emission wavelengths is of utmost importance. Here, we report on

Classical bosonic systems may be tailored to support topological order and unidirectional edge transport exploiting gauge fields. Here, we theoretically explore how synthetic gauge fields may be used to induce higher-order topological phases and zero-energy boundary states. We demonstrate these principles in two types of three-dimensional topolectrical circuits with synthetic gauge fields threading

We develop a semiclassical theory of laser oscillation into a chiral edge state of a topological photonic system endowed with a frequency-dependent gain. As an archetypal model of this physics, we consider a Harper–Hofstadter lattice embedding population-inverted, two-level atoms as a gain material. We show that a suitable design of the spatial distribution of gain and its spectral shape provides flexible

The collective response of a system is profoundly shaped by the interaction dynamics between its constituent elements. In physics, tailoring these interactions can enable the observation of unusual phenomena that are otherwise inaccessible in standard settings, ranging from the possibility of a Kramer’s degeneracy even in the absence of spin to the breakdown of the bulk-boundary correspondence. Here

Adaptive optics methods have long been used to perform complex light shaping at the output of a multimode fiber (MMF), with the specific aim of controlling the emitted beam in the near field and enabling the realization of a new generation of endoscopes based on a wide variety of spectroscopic techniques. Gaining control of other emission properties, including the far-field pattern and the phase of

We developed superconducting nanowire single-photon detectors based on tungsten silicide, which show saturated internal detection efficiency up to a wavelength of 10 μm. These detectors are promising for applications in the mid-infrared requiring sub-nanosecond timing, ultra-high gain stability, low dark counts, and high efficiency, such as chemical sensing, LIDAR, dark matter searches, and exoplanet

Electrical excitation of surface plasmon polaritons by inelastic tunneling electrons has been put forward as a potential nanosource that can be used in a variety of on-chip optoelectronic applications. In this article, we report a source based on an array of gold cylindrical antennas deposited on an alumina tunnel junction. This configuration has several merits: the junction can be operated under a

In order to greatly promote impressive applications in terahertz (THz) photonics, research on active optoelectronic THz devices with high performance such as modulators is still a vital work. Electrically controlled THz modulators with a large modulation depth and wide modulation bandwidth are urgently needed for THz technology. Herein, a bismuth (Bi) nanofilm is rationally designed as an electrically

We synthesized cesium lead-halide perovskite colloidal nanocrystals using the hot injection method for wide-color-gamut low-cost displays. An efficient surface defect passivation technique was applied to further improve the optical performance of the green and red perovskite nanocrystals. The prepared perovskite nanocrystal solutions were formulated into inkjet printable homogeneous inks and uniformly

The Talbot effect, epitomized by periodic revivals of a freely evolving periodic field structure, has been observed with waves of diverse physical nature in space and separately in time, whereby diffraction underlies the former and dispersion underlies the latter. To date, a combined spatiotemporal Talbot effect has not been realized in any wave field because diffraction and dispersion are independent

The challenging requirements of large scale quantum information processing using parametric heralded single photon sources involve maximizing the interference visibility while maintaining an acceptable photon generation rate. By developing a general theoretical framework that allows us to include a large number of spatial and spectral modes together with linear and non-linear optical elements, we investigate

In comparison with conventional lasers, topological lasers are more robust and can be immune to disorder or defects if lasing occurs in topologically protected states. Previously reported topological lasers were almost exclusively based on the first-order photonic topological insulators. Here, we show that lasing can be achieved in the zero-dimensional corner state in a second-order photonic topological

Chiral exceptional points (CEPs) have been shown to emerge in traveling wave resonators via asymmetric back scattering from two or more nano-scatterers. Here, we provide a new perspective on the formation of CEPs based on the coupled oscillator model. Our approach provides an intuitive understanding for the modal coalescence that signals the emergence of CEPs and emphasizes the role played by dissipation

Polarization singularities, describing the points where the state of polarization is indeterminate, reveal the polarization topology in vectorial optical fields, which include two-/three-dimensional topologies such as C-points, V-points, L-lines, Möbius strips, links, and knots. Compared with the phase singularities, it has more parameters to manipulate, which bring forth a series of novel optical

Surface polaritons comprise a wealth of light–matter interactions with deep sub-wavelength scale confinement of electromagnetic modes. However, their nanoscale localized dissipation and thermalization processes are not readily accessible experimentally. Here, we introduce photothermal force microscopy to image surface plasmon polaritons (SPPs) in monolayer graphene through their non-radiative SiO2

We report high-speed performance for a photodetector operating at zero bias—with zero dark current and zero DC electrical power dissipation. Photocurrent generation is achieved through phonon-assisted absorption in a silicon microring resonator embedded with silicon-germanium, resulting in a responsivity of 0.35 and 0.043 A/W at wavelengths around 1180 and 1270 nm, respectively. We measure a 3 dB bandwidth

To improve the accuracy of material identification in millimeter- and terahertz-wave nondestructive imaging during security and other inspections, it is important to perform both amplitude and phase imaging. Highly coherent sources generated based on the frequency multiplication of stable microwave sources are promising for these applications. However, this method reduces the fidelity of the image

Despite the rapidly growing interest in exploiting millimeter and terahertz waves for wireless data transfer, the role of reflected non-line-of-sight (NLOS) paths in wireless networking is one of the least explored questions. In this paper, we investigate the idea of harnessing these specular NLOS paths for communication in directional networks at frequencies above 100 GHz. We explore several illustrative

Compact photonic elements that control both the diffraction and interference of light offer superior performance at ultra-compact dimensions. Unlike conventional optical structures, these diffractive optical elements can provide simultaneous control of spectral and spatial profiles of light. However, the inverse design of such a diffractive optical element is time-consuming with current algorithms

We propose Fourier microscopy based on single-pixel imaging, which uses structured light to computationally illuminate a sample and uses a two-dimensional (2D) pixelated detector to capture the Fourier spectrum image in the back focal plane of the objective. The Fourier spectra collected by different pixels of the detector correspond to light waves diffracted at different angles. Therefore, by regrouping

Quantitative phase imaging (QPI) has been widely applied in characterizing cells and tissues. Spatial light interference microscopy (SLIM) is a highly sensitive QPI method due to its partially coherent illumination and common path interferometry geometry. However, SLIM’s acquisition rate is limited because of the four-frame phase-shifting scheme. On the other hand, off-axis methods such as diffraction

An opto-electronic neural network is designed for video object detection from a long-exposure blurred image. This network combines an optical encoder, convolutional neural network decoder, and object detection module, which are jointly optimized end-to-end. The joint loss is adopted for updating the network according to the physical constraints of hardware via back-propagation. A high-speed refreshed

We report on efficient THz generation in DAST by optical rectification of intense mid-IR pulses centered at (i) 3.9 μm and (ii) its second harmonic at 1.95 μm. Suppression of multi-photon absorption shifts the onset of saturation of the THz conversion efficiency to pump energy densities, which are almost an order of magnitude higher as compared to conventional pump schemes at 1.5 μm. Despite strong

We study the properties of nonlinear Bloch waves in a diamond chain waveguide lattice in the presence of a synthetic magnetic flux. In the linear limit, the lattice exhibits a completely flat (wavevector k-independent) band structure, resulting in perfect wave localization, known as Aharonov–Bohm caging. We find that in the presence of nonlinearity, the Bloch waves become sensitive to k, exhibiting

The machine learning technique of persistent homology classifies complex systems or datasets by computing their topological features over a range of characteristic scales. There is growing interest in applying persistent homology to characterize physical systems such as spin models and multiqubit entangled states. Here, we propose persistent homology as a tool for characterizing and optimizing band

Topologically protected states are important in realizing robust excitation transfer between distant sites in photonic lattices. Here, we propose an efficient gap-protected transfer of photons in a scalable one-dimensional waveguide array by transporting the topological defect state of a Su–Schrieffer–Heeger model. The separation between neighboring waveguides is designed according to the Jaynes–Cummings

Beams carrying orbital-angular-momentum (OAM) have gained much interest due to their unique amplitude and phase structures. In terms of communication systems, each of the multiple independent data-carrying beams can have a different OAM value and be orthogonal to all other beams. This paper will describe the use of multiplexing and the simultaneous transmission of multiple OAM beams for enhancing the

Singlet lenses are free from precise assembling, aligning, and testing, which are helpful for the development of portable and low-cost microscopes. However, balancing the spectrum dispersion or chromatic aberrations using a singlet lens made of one material is difficult. Here, a novel method combining singlet lens microscopy and computational imaging, which is based on deep learning image-style-transfer

We demonstrate an individual single-walled carbon nanotube light emitter integrated onto a microcavity and a waveguide operating in the telecom wavelength regime. Light emission from the carbon nanotube is enhanced at the cavity resonance and is efficiently extracted from the waveguide facet. We have transferred carbon nanotubes to a nanobeam cavity with a dry process, ensuring that an individual carbon

Radiative cooling, which normally requires relatively high infrared (IR) emissivity, is one of the insects’ effective thermoregulatory strategies to maintain their appropriate body temperature. Recently, the physical correlation between the delicate biological microstructures and IR emissivity for thermal radiation draws increased attention. Here, a scent patch region on the hindwing of Rapala dioetas

Nanotechnology and modern materials science demand reliable local probing techniques on the nanoscopic length scale. Most commonly, scanning probe microscopy methods are applied in numerous variants and shades, for probing the different sample properties. Scattering scanning near-field optical microscopy (s-SNOM), in particular, is sensitive to the local optical response of a sample, by scattering

We present a double-layer dielectric metasurface obtained by stacking a silicon nanodisk array and a silicon photonic crystal slab with equal periodicity on top of each other. We focus on the investigation of electric near-field enhancement effects occurring at resonant excitation of the metasurface and study its optical properties numerically and experimentally. We find that the major difference in

Since localized surface plasmon (LSP) is capable of generating strong electromagnetic fields, it has achieved extensive applications in surface-enhanced Raman scattering (SERS). As opposed to this, surface plasmon polariton (SPP) has been rarely employed for its weak electric field enhancement. The present study proposed an Ag nanoparticles (AgNPs) and multilayer Au/Al2O3 film (MLF) hybrid system,

Microcavities are used for resonantly enhanced interactions of light with matter or particles. Usually, the resonator’s sensitivity drops down with every particle attached to its interface due to the inherent scattering losses and the corresponding degradation of the optical quality factor. Here, we demonstrate, for the first time, a hybrid resonator made of a dielectric disk and a continuous membrane

Optical modulation plays arguably the utmost important role in microwave photonic (MWP) systems. Precise synthesis of modulated optical spectra dictates virtually all aspects of MWP system quality including loss, noise figure, linearity, and types of functionalities that can be executed. However, for such a critical function, the versatility to generate and transform analog optical modulation is severely

We develop a new type of high-speed wavefront determination method with single feedback measurement to focus light through a 15.2 scattering mean free path in ∼113 ms. Our method is based on a heterodyne-detection phase sensitivity interferometer. First, the matrix which describes the light propagation process in the sample is measured by single input and output optical fields’ analysis. Then, by using

We investigate intermodal forward Brillouin scattering in a solid-core photonic crystal fiber (PCF), demonstrating efficient power conversion between the HE11 and HE21 modes, with a maximum gain coefficient of 21.4 W−1 km−1. By exploring mechanical modes of different symmetries, we observe both polarization-dependent and polarization-independent intermodal Brillouin interaction. Finally, we discuss

Deterministic coupling between photonic nodes in a quantum network is an essential step toward implementing various quantum technologies. The omnidirectionality of free-standing emitters, however, makes this coupling highly inefficient, in particular if the distant nodes are coupled via low numerical aperture (NA) channels such as optical fibers. This limitation requires placing quantum emitters in

We demonstrate second harmonic generation by using an amorphous silicon metamaterial fabricated on the tip of an optical fiber that collects the generated light. The metamaterial is a double-chevron array that supports a closed-mode resonance for the fundamental wavelength at 1510 nm with a quality factor of 30. The normalized resonant second harmonic conversion efficiency calculated per intensity

Infrared (IR) radiation detectors are used in numerous applications from thermal imaging to spectroscopic gas sensing. Obtaining high speed and sensitivity, low-power operation, and cost-effectiveness with a single technology remains to be a challenge in the field of IR sensors. By combining nano-thermoelectric transduction and nanomembrane photonic absorbers, we demonstrate uncooled IR bolometer technology

Holographic wavefront manipulation enables converting hair-thin multimode optical fibers into minimally invasive lensless imaging instruments conveying much higher information densities than conventional endoscopes. Their most prominent applications focus on accessing delicate environments, including deep brain compartments, and recording micrometer-scale resolution images of structures in close proximity

Optical nanocavities formed by defects in a two-dimensional photonic crystal (PC) slab can simultaneously realize a very small modal volume and an ultrahigh quality factor (Q). Therefore, such nanocavities are expected to be useful for the enhancement of light–matter interaction and slowdown of light in devices. In the past, it was difficult to design a PC hole pattern that makes sufficient use of