Metasurfaces substituted for naturally occurring materials make it possible to develop flat optics manipulating terahertz waves. However, the control of unprecedented material properties with metasurfaces frequently produces anisotropic material properties and has yet to be commonly adopted because of the limitation of functionalities as optical components. Here, we demonstrate an isotropic metasurface

We present an experimental study of optical time-refraction caused by time-interfaces as short as a single optical cycle. Specifically, we study the propagation of a probe pulse through a sample undergoing a large refractive index change induced by an intense modulator pulse. In these systems, increasing the refractive index abruptly leads to time-refraction where the spectrum of all the waves propagating

Emerging 3D photonic circuits would greatly benefit from the ability to integrate skimming waveguides with low loss and controllable inscription depth into photonic circuits. These waveguides allow for the interaction of guiding light directly with external modulation signals and enable programmable photonic circuits. Here, we report the fabrication of a novel photonic-lattice-like skimming waveguide

There is a pressing global need to increase the use of renewable energy sources and limit greenhouse gas emissions. Towards this goal, highly efficient and molecularly selective chemical processes that operate under mild conditions are critical. Plasmonic photocatalysis uses optically-resonant metallic nanoparticles and their resulting plasmonic, electronic, and phononic light-matter interactions to

Impurity-vacancy centers in diamond offer a new class of robust photon sources with versatile quantum properties. While individual color centers commonly act as single-photon sources, their ensembles have been theoretically predicted to have tunable photon-emission statistics. Importantly, the particular type of excitation affects the emission properties of a color center ensemble within a diamond

Here, we show that isorefractive spacetime crystals with a travelling-wave modulation may mimic rigorously the response of moving material systems. Unlike generic spacetime crystals, which are characterized by a bi-anisotropic coupling in the co-moving frame, isorefractive crystals exhibit an observer-independent response, resulting in isotropic constitutive relations devoid of any bianisotropy. We

Moulding the flow of phononic waves in three-dimensional (3D) space plays a critical role in controlling the sound and thermal properties of matter. To this end, 3D phononic crystals (PnCs) have been considered the gold standard because their complete phononic bandgap (PnBG) enables omnidirectional inhibition of phononic wave propagation. Nevertheless, achieving a complete PnBG in the high-frequency

Charge transfer plasmon (CTP) modes arise when metallic nanoparticle dimers are connected by a conductive junction. This offers a unique opportunity to explore electron transport at optical frequencies as well as to attain narrow plasmon resonances that can be broadly modulated from visible to IR regimes, implying their potentials for applications in single-molecule electronics and sensing. This article

Localized surface plasmon polaritons can confine the optical field to a single-nanometer-scale area, strongly enhancing the interaction between photons and molecules. Theoretically, the ultimate enhancement might be achieved by reducing the “photon size” to the molecular extinction cross-section. In addition, desired control of electronic transitions in molecules can be realized if the “photon shape”

Nondiffracting Bessel surface plasmon polariton (SPP) beams, which have unique self-healing, non-divergence, and linear transmission properties, have charming applications in plasmonic devices and on-chip interconnection circuits. Here we first realize, to the best of our knowledge, the ultrafast control and imaging of the Bessel SPP pulse on the nano-femto scale in the experiment. We demonstrate ultrafast

With the development of all-optical networks, all-optical devices have become a research hotspot in recent years. Two-dimensional materials, represented by graphene and black phosphorus, have attracted great interest in the scientific community due to their excellent optical, electrical, magnetic, and mechanical properties. Bridging the gap between fiber optics and nanotechnology, microfibers can interact

The inverse Faraday effect is a magneto-optical process allowing the magnetization of matter by an optical excitation carrying a non-zero spin of light. This phenomenon was considered until now as symmetric; right or left circular polarizations generate magnetic fields oriented in the direction of light propagation or in the counter-propagating direction. Here, we demonstrate that by manipulating the

Efficient electrical generation of mid-infrared light is challenging because of the dearth of materials with natural dipole-active electronic transitions in this spectral region. One approach to solve this problem is through quantum-engineering of the electron dispersion to create artificial transitions, as in quantum cascade devices. In this work we propose an alternative method to generate mid-infrared

The polar nature of calcite results in lattice vibrations that can be stimulated through gratings and nanostructures to design spatially and spectrally coherent thermal radiation patterns. In order to obtain optimal design control over such patterned materials, it is first necessary to understand the fundamental emissivity properties of the lattice vibrations themselves. Because calcite is a uniaxial

The demand on broadband near-infrared photodetections with high responsivity is becoming increasingly eminent; however its realization remains a significant technological challenge. Here we design, fabricate, and characterize a broadband Ge photodetector (1000–1600 nm), composed of densely packed 230-nm-thick Ge disks of different diameters (255 nm, 320 nm, and 500 nm), placed on top of a 105-nm-thin

High-index dielectric nanoantennas, which provide an interplay between electric and magnetic modes, have been widely used as building blocks for a variety of devices and metasurfaces, both in linear and nonlinear regimes. Here, we investigate hybrid metal-semiconductor nanoantennas, consisting of a multimode silicon nanopillar core coated with a gold layer, that offer an enhanced degree of control

In most rotational Doppler effect (RDE) measurements, the optical axis and the rotating axis of the object are required to be aligned. However, the condition is very difficult to achieve in practical applications of rotation detection, which seriously affects the received signal. Moreover, it is necessary to focus the beam on the rotating axis of a rotating surface in applications ranging from manufacturing

Spintronic terahertz (THz) emission via spin-to-charge conversion (SCC) has been widely studied in ferromagnets (FM)/nonmagnets (NM) structures, in which various mechanisms of SCC have been confirmed in different NM materials. However, it is rare to find a material having multiple SCC mechanisms at the same time. Here, we report a ferromagnetic metal Ni film with diverse functions in the SCC process

We propose reconfigurable anomalous reflectors with stretchable elastic substrates. The proposed reflector dynamically controls the reflection direction by mechanically stretching the substrate to induce a physical change of the unit cell period. Owing to the simple and scalable tuning mechanism, the proposed approach is applicable in the millimeter-wave and terahertz bands for a wide reflection steering

Anisotropic Self-Complementary Metasurfaces (SC-MTSs) are structures constituted by an alternation of complementary inductive and capacitive strips, which are “self-dual” according to Babinet’s duality principle. They support the propagation of two orthogonally polarized surface-wave modes with the same phase velocity along the principal directions (i.e., along the strips and normal to them). The isofrequency

When light interacts with matter by means of scattering and absorption, we observe the resulting color. Light also probes the symmetry of matter and the result is encoded in its polarization. In the special case of circularly-polarized light, which is especially relevant in nonlinear optics, quantum photonics, and physical chemistry, a critical dimension of symmetry is along the longitudinal direction

Passive daytime radiative cooling (PDRC) as a zero-energy cooling technology that reflects most of sunlight and emits infrared thermal radiation to outer space, has attracted much attention. However, most PDRC materials suffer dust accumulation problem during long-term use, seriously detrimental to their cooling performance. Here, we demonstrate a micro-structured polyethylene film fabricated through

We propose a metasurface antenna capable of real-time holographic beam steering. An array of reconfigurable dipoles can generate on-demand far-field patterns of radiation through the specific encoding of meta-atomic states i.e., the configuration of each dipole. Suitable states for the generation of the desired patterns can be identified using iteration, but this is very slow and needs to be done for

All-inorganic lead halide perovskite nanocrystals (NCs) have been widely investigated as highly promising optical gain materials due to their compelling electrical and optical properties. Although many efforts have been carried out, a deep understanding of perovskite NC vertical-cavity surface-emitting lasers (VCSELs) is elusive, which is very important in the development of photoelectronic integrated

All-dielectric nanoarrays have strong electromagnetic resonances with various interesting applications and are tuned by adjusting their geometrical parameters. However, their optical properties are permanently encoded during fabrication. This study presents robust dynamically tunable all-dielectric nanoresonators for controllable, reversible, and reproducible color filtering. Our design uses an array

Chirality (C) is a fundamental symmetry property of objects. Detecting and distinguishing molecular chirality in the infrared spectrum is important in life sciences, biology, and chemistry. In this paper, we demonstrate an achiral metasurface based on a gaped dual-germanium-dimer array for enhanced mid-infrared chiral sensing under both circularly polarized light (CPL) and linearly polarized light

We demonstrate heterogeneous integration of active semiconductor materials into the conventional passive metal-insulator-metal (MIM) waveguides to provide compact on-chip light generation and detection capabilities for chip-scale active nanophotonic platforms. Depending on its bias conditions, a metal-semiconductor-metal section can function as either a light emitting diode or a photodetector directly

Designing a monochromatic spatially-structured light field that recovers the pre-specified profile of optical force (OF) exerted on a particle is an inverse problem. It usually requires high dimensional optimization and involves lengthy calculations, thus remaining little studied despite decades of research on OF. We report here the first attempt to attack this inverse design problem. The modus operandi

Symmetry-protected bound states in the continuum (SP-BICs) are one of the most intensively studied BICs. Typically, SP-BICs must be converted into quasi-BICs (QBICs) by breaking the unit cell’s symmetry so that they can be accessed by the external excitation. The symmetry-broken usually results in a varied resonance wavelength of QBICs which are also highly sensitive to the asymmetry parameters. In

The possibility of creating and manipulating nanostructured materials encouraged the exploration of new strategies to control electromagnetic properties. Among the most intriguing nanostructures are those that respond differently to helical polarization, i.e., exhibit chirality. Here, we present a simple structure based on crossed elongated bars where light-handedness defines the dominating cross-section

This review article focuses on the latest achievements in the creation of a class of electrotuneable optical metamaterials for switchable mirrors/windows, variable colour mirrors, optical filters, and SERS sensors, based on the voltage-controlled self-assembly of plasmonic nanoparticles at liquid/liquid or solid/liquid electrochemical interfaces. Practically, these experimental systems were navigated

Plasmonic optical nanolithography using extraordinary optical transmission through a metallic nanohole mask has been actively applied to the high-resolution fabrication of nanostructures over a large area. Although there have been studies on improving the nanostructure fabrication performance in optical nanolithography, such as on adjustable external gap spacing, additional performance enhancement

Enhanced directionality of photoluminescence emission has attracted attention due to its diverse application areas ranging from single-photon sources to fluorescence sensing and bio-imaging. Utilization of null phase advance in epsilon-near-zero (ENZ) medium is an important scheme to achieve the directive emission. Despite various designs proposed for ENZ-based directive emission, most of the ENZ mediums

To prevent the crosstalk between adjacent waveguides in photonic integrated circuits, the minimum thickness of the cladding layers is around half a wavelength, which imposes a fundamental limitation to further integration and miniaturization of photonic circuits. Here, we reveal that epsilon-near-zero claddings, either isotropic or anisotropic, can break the above bottleneck by prohibiting the crosstalk

In this paper, the influence of classical signals on quantum key distribution (QKD) is studied over multi-core fiber (MCF) when optical amplifiers exist. Firstly, the long-distance simultaneous transmission architectures of QKD and classical signals are proposed based on advanced asymmetric sending or not sending QKD (SNS-QKD) and classical Bennett–Brassard 1984-QKD (BB84-QKD), and the segment length

When assembled in periodic arrangements, metallic nanostructures (NSs) support plasmonic surface lattice (SL) resonances resulting from long-range interactions these surface lattice resonances differ radically from localized surface plasmon (LSP). Similarly to the hybridization of LSP resonances, observed in short-range interactions, we demonstrate the possibility to generate a hybridization of surface

We have studied four 2D layered perovskites, including OA2PbI4 (RP phase), ODAPbI4 and BDAPbI4 (DJ phase), (GA)MAPbI4 (ACI phase), where OA is [(C m H2m+1)NH3](m = 8), ODA is [NH3(CH2) m NH3](m = 8), BDA is [NH3(CH2) m NH3](m = 4), and GA is [C(NH2)3]; RP, DJ, and ACI means Ruddlesden–Popper, Dion–Jacobson and alternating cations in the interlayer, respectively. The temperature dependence of absorption

Oblique plane microscopy (OPM) directly captures object information in a plane tilted from the focal plane of the objective lens without the need for slow z-stack acquisition. This unconventional widefield imaging approach is made possible by using a remote focusing principle that eliminates optical aberrations for object points beyond the focal plane. Together with oblique lightsheet illumination

Exceptional points (EPs) are degenerate singularities in a non-Hermitian system that can be induced by controlling the interaction between resonant photonic modes. EPs can enable unusual optical phenomena and significantly enhance the optical sensitivity under small perturbations. However, most studies thus far have been limited to static photonic structures. In this study, we propose and experimentally

In a reciprocal medium, transmission of electromagnetic (EM) waves is symmetric along opposite directions which restrict design and implementation of various systems in optics and photonics. Asymmetric transmission (AT) is essential for designing isolators and circulators in optics and photonics, and it benefits other applications such as photovoltaic systems, lasers, cloaking, and EM shielding. While

Dynamic optical metasurfaces with ultrafast temporal response, i.e., spatiotemporal optical metasurfaces, provide attractive solutions and open fascinating perspectives for modern highly integrated optics and photonics. In this work, electro-optically controlled optical metasurfaces operating in reflection and utilizing resonant waveguide mode excitation are demonstrated from the viewpoint of free-space

Second harmonic generation (SHG) microscopy is a commonly used technique to study the organization of collagen within tissues. However, individual collagen fibrils, which have diameters much smaller than the resolution of most optical systems, have not been extensively investigated. Here we probe the structure of individual collagen fibrils using polarization-resolved SHG (PSHG) microscopy and atomic

Coronavirus disease 2019 (COVID-19) is a newly emerging human infectious disease that continues to develop new variants. A crucial step in the quest to reduce the infection is the development of rapid and reliable virus detectors. Here, we report a chip scale photonic sensing device consisting of a silicon-nitride double microring resonator (MRR) for detecting SARS-CoV-2 in clinical samples. The sensor

Infrared camouflage is an effective technique to avoid many kinds of target detection by detectors in the infrared band. For a high-temperature environment, thermal management of selective emission is crucial to dissipate heat in the mid-infrared non-atmospheric window (5–8 μm). However, it still remains challenges for balancing infrared camouflage and thermal management. Here, we experimentally demonstrate

Recent advances in inverse-design approaches for discovering optical structures based on desired functional characteristics have reshaped the landscape of nanophotonic structures, where most studies have focused on how light interacts with nanophotonic structures only. When quantum emitters (QEs), such as atoms, molecules, and quantum dots, are introduced to couple to the nanophotonic structures, the

The plasma sheath causes the spacecraft’s communication signal to attenuate dramatically during the re-entry period, which seriously threatens the astronauts. However, valid experimental protocols have not been obtained hitherto. To realize the propagation of electromagnetic waves in negative permittivity background of the plasma sheath, alumina columns are embedded in the plasma background to form

Distinguishing between the left- and right-handed versions of a chiral molecule (enantiomers) is vital, but also inherently difficult. Traditional optical methods using elliptically/circularly polarized light rely on linear effects which arise beyond the electric-dipole approximation, posing major limitations for ultrafast spectroscopy. Here we show how to turn an ultrashort elliptical pulse into an

The efficient generation, accurate detection, and detailed physical tracking of energetic electrons are of applied interest for high harmonics generation, electron-impact spectroscopy, and femtosecond time-resolved scanning tunneling microscopy. We here investigate the generation of photoelectrons (PEs) by exposing plasmonic nanostructures to intense laser pulses in the infrared (IR) spectral regime

Surface-enhanced infrared absorption (SEIRA) spectroscopy is a competent method to detect trace quantity of molecules and even protein conformational flexibility by enhancing their vibrational modes. To improve the spectroscopy features, we propose a surface with honeycomb-like (HC) arrangement of aluminum equilateral triangles within a metal-insulator-metal configuration. With adjustable geometric

Coupling of surface plasmon polaritons (SPPs) supported by graphene and hyperbolic phonon polaritons (HPPs) supported by hyperbolic materials (HMs) could effectively promote photon tunneling, and hence the radiative heat transfer. In this work, we investigate the polariton hybridization phenomena on near-field radiative heat transfer (NFRHT) in multilayer heterostructures, which consist of periodic

One of the prime applications of squeezed light is enhancing the sensitivity of an interferometer below the quantum shot-noise limit, but so far, no such experimental demonstration was reported when using the optical Kerr effect. In prior setups involving Kerr-squeezed light, the role of the interferometer was merely to characterize the noise pattern. The lack of such a demonstration was largely due

Droplets provide unique opportunities for the investigation of laser-induced surface chemistry. Chemical reactions on the surface of charged droplets are ubiquitous in nature and can provide critical insight into more efficient processes for industrial chemical production. Here, we demonstrate the application of the reaction nanoscopy technique to strong-field ionized nanodroplets of propanediol (PDO)

Using tip-enhanced photoluminescence (TEPL), we investigate micron-size monolayer MoS2 flakes. In a sequence of studies, we apply various voltages between the Ag-coated nano-tip and the MoS2 flakes and observe an intriguing result. During the TEPL measurement, we observe that the photoluminescence spectrum is blue shifted and the overall signal intensity is increased. We attribute this behavior to

The study of spin–orbit coupling (SOC) of light is crucial to explore the light–matter interactions in sub-wavelength structures. By designing a plasmonic lattice with chiral configuration that provides parallel angular momentum and spin components, one can trigger the strength of the SOC phenomena in photonic or plasmonic crystals. Herein, we explore the SOC in a plasmonic crystal, both theoretically

The rapid development of optical technologies, such as optical manipulation, data processing, sensing, microscopy, and communications, necessitates new degrees of freedom to sculpt optical beams in space and time beyond conventionally used spatially homogenous amplitude, phase, and polarization. Structuring light in space and time has been indeed shown to open new opportunities for both applied and

Three-dimensional (3D) information is vital for providing detailed features of the physical world, which is used in numerous applications such as industrial inspection, automatic navigation and identity authentication. However, the implementations of 3D imagers always rely on bulky optics. Metasurfaces, as the next-generation optics, shows flexible modulation abilities and excellent performance combined

The scattering matrix is the mathematical representation of the scattering characteristics of any scatterer. Nevertheless, except for scatterers with high symmetry like spheres or cylinders, the scattering matrix does not have any analytical forms and thus can only be calculated numerically, which requires heavy computation. Here, we have developed a well-trained deep neural network (DNN) that can

Terahertz (THz) waves are a highly sensitive probe of free carrier concentrations in semiconducting materials. However, most experiments operate in the far-field, which precludes the observation of nanoscale features that affect the material response. Here, we demonstrate the use of nanoscale THz plasmon polaritons as an indicator of surface quality in prototypical quantum devices properties. Using

Recent advances in near-field technology with an ultrahigh spatial resolution breaking optical diffraction limit, make it possible to further identify surface-enhanced Raman scattering (SERS) enhancement theories, and to monitor the SERS substrates. Here we verify the electromagnetic enhancement mechanism for SERS with a close-up view, using scattering-type scanning near-field optical microscopy. The

Nonlinear frequency mixings have shown an alternative way to create new electromagnetic sources in frequency ranges that are difficult to access with conventional techniques. To simultaneously use the fundamental frequency pump beam and multiple harmonic signals generated in the same channel, a device capable of separating each frequency component is required. Here, we propose and experimentally demonstrate