Nanophotonics (Berlin, Germany)最新文献

Controlling near-field electromagnetic interactions is central to tailoring optical responses in plasmonic systems. However, the static nature of conventional noble metal nanostructures limits their application in active photonic devices. In this work, we design and experimentally demonstrate a composite graphene metasurface, composed of an octagonal frame coupled to a central heptamer disk, that enables multidimensional and active control over hybrid plasmons. The observed rich spectral features originate from hybridization between the dipolar and higher-order modes of the frame and the collective resonances of the heptamer. We show that the polarization of incident light serves as an effective control parameter for engineering the radiative properties of these modes. By varying the polarization angle, specific resonances can be selectively driven into super-radiant states with enhanced radiation or sub-radiant states with suppressed emission. In parallel, electrostatic gating provides a second, independent tuning mechanism that enables wide, continuous, and robust spectral modulation, in excellent agreement with theoretical predictions. The combined use of structural design, polarization control, and electrical tuning transforms a static metasurface into a dynamically reconfigurable platform. This dual control over both resonance frequency and radiative coupling offers a comprehensive toolkit for on-demand manipulation of light-matter interactions, paving the way for advanced optical modulators, reconfigurable filters, and tunable sensing technologies.

Molecular chirality plays an important role in chemistry and biology, allows control of biological interactions, affects drug efficacy and safety, and promotes synthesis of new materials. In general, chirality manifests itself in optical activity (circular dichroism and/or circular birefringence). Chiral plasmonic nanoparticles have been recently developed for molecular enantiomer separation, chiral sensing and chiral photocatalysis. Here, we show that optical chirality of plasmonic nanoparticles exhibiting strong scattering can remain completely undetected using standard characterisation techniques, such as circular dichroism measurements. This phenomenon, which we term meso-chiral in analogy to meso-compounds in chemistry, is based on mutual cancellation of absorption and scattering chiral responses. As a prominent example, the meso-chiral behaviour has been numerically demonstrated in multi-wound-SiO₂/Au nanoparticles over the entire visible spectral range and in other prototypical chiral nanoparticles in narrower spectral ranges. The meso-chiral property has been experimentally verified by demonstrating chiral absorption of gold helicoid nanoparticles at the wavelength where conventional circular dichroism measurements show absence of a chiral response. These findings demonstrate a valuable link between microscopic and macroscopic manifestations of chirality and can provide insights for interpreting a wide range of experimental results and designing chiral properties of plasmonic nanoparticles.

Optical metasurfaces, as a booming research field, have provided new methods for modulating the amplitude, phase, and polarization of light through artificial birefringent structures or structural resonances. It has been used to design planar optical components such as ultra-thin lenses, ultra-wideband achromatic lenses, and orbital angular momentum (OAM) generators. However, existing surveys typically examine either metasurface fundamentals or a single display modality, leaving no comprehensive roadmap that connects meta-atom design to full-device performance, hereafter, the term meta-atom are denoted to be an individual sub-wavelength building block of a metasurface. Here we present the first cross-scale review that quantitatively bridgices phase-dispersion engineering at the nanostructure level with system-level figures-of-merit across three mainstream 3D display paradigms, computer-generated holography, light-field projection, and near-eye/retinal displays. By critically benchmarking more than 150 demonstrations published between 2019 and 2025, we extract practical lookup charts that guide practitioners from material choice and meta-atom geometry to field-of-view, depth acuity, efficiency, and form-factor targets. Thanks to metasurfaces' high integration density and functional diversity, its application in the light field display has attracted great interest. Metasurface can effectively improve the shortcomings of low spatial resolution, low diffraction efficiency, and narrow field of view common in traditional display components. In this paper, we first review the phase modulation method and structure resonance principle of metasurface. Then, we examine their application in the holographic display field and review the approaches for achieving structural-color printing. We summarize the 3D display methods of holographic display, light field display, and near-eye display and discuss how metasufaces enhance each modality. Finally, we distill emerging inflection points: AI assisted inverse design, dynamically tunable multifunctional platforms, and quantum or cascaded architectures into a looking forward commercialization roadmap that addresses the challenges still facing the 3D display industry.

Refractive index is a fundamental electromagnetic (EM) parameter that can describe photonic continuous media (PCM) traditionally as either transparency or opacity. Recently, topological theory offers a new set of phases to characterize PCM as either trivial or nontrivial, by using topological invariant which are not direct to EM parameters. As all of the optical properties in PCM should be related to EM parameters, we formulate a topological index based on EM parameters and establish its phase map in this work. The map can analytically describe the deterministic condition for a topologically nontrivial phase. Our findings indicate that the topology of 2D bi-anisotropic PCM is determined by the sign of the topological index. Another EM parameter of pseudo surface impedance is also introduced for the opaque regions of PCM, showing the topological opacity has a full range of impedance values ranging from negative to positive, while the trivial case only has either negative or positive impedance. The simulation results show that an interface between two opacities with differing index signs can support robustly optical propagation of topological edge states. The proposal of EM-parameter method reveals a deep understanding on topological properties of PCM, and will enrich the topological theory in photonic systems.

We investigate the coupling effects between a double-resonance split-ring resonators (SRRs) design and the epsilon-near-zero (ENZ) guided mode of ultrathin indium tin oxide (ITO) films on second-harmonic generation (SHG). The optimized SRRs with an aspect ratio of 0.3 support a magnetic dipole (MD) resonance within the ENZ regime of ITO and a higher-order resonance at the SH frequency to achieve mode matching under cross-polarized excitation. The SRR-ITO coupled system (as opposed to the nanorod-ITO coupled system) was found to perform constructive (destructive) polarization interference between the nonlinear polarization currents at the upper hybridized modes (ω⁺) and the linear electric field at SH frequency (2ω⁺), resulting in a 1218-fold SHG enhancement outperformed than that of the nanorod-ITO coupled system, as predicted by overlap integral analysis. The measured SHG conversion efficiency for the SRR-ITO coupled system exceeds 10^-7 at an excitation wavelength of 1,320 nm, corresponding to a one-order (two-order) of magnitude enhancement compared to the nanorod-ITO coupled system (Au/ITO film). These findings highlight the potential of the proposed hybrid metasurfaces for efficient cross-polarized nonlinear signal generation, paving the way for advanced applications such as light sources, modulators in integrated photonic circuits, and biological sensing.

We demonstrate a label-free, far-field super-resolution imaging approach based on photonic nanojets generated by tapered dielectric fibers. By systematically analyzing the dependence of nanojet confinement and focal distance on cylinder diameter (8-16 μm), we establish a geometric design framework for tunable light localization below the diffraction limit. Using this insight, we fabricate a 12-μm waist-tapered optical fiber that produces a laterally extended nanojet for non-contact imaging. This configuration resolves grating lines with 92 nm width and spacing - dimensions beyond the classical resolution limit. Ray tracing simulations confirm the experimental magnification trend and show that fiber tilt enables tunable control over magnification and field of view. Our fiber platform provides scalable alignment, mechanical tunability, and extended working distances. These findings establish tapered fibers as compact and flexible photonic elements for delivering sub-wavelength light confinement, with applications in optical metrology, field enhancement, and scanning nanophotonic systems.

Thin-film lithium niobate (TFLN) has played a pivotal role in the advancement of integrated photonics, by supporting a diverse range of applications including nonlinear optics, electro-optics, and piezo-optomechanics. The effective realization and enhancement of these interactions rely heavily on the implementation of high quality photonic microresonators. The pursuit of novel resonator architectures with optimized properties thus represents a central research area in TFLN photonics. In this work, we design and fabricate TFLN Fabry-Perot microresonators, by placing a straight section of waveguide between a pair of tapered photonic crystal mirrors. The resonator features a high quality factor of 6 × 10⁵ at 1,530 nm and a compact length of 100 µm. The functionality of the device is further demonstrated by integrating on-chip electrodes for high-frequency piezo-optomechanical modulation. Our device can serve as an appealing candidate for developing high-performance photonic components on the TFLN platform.

Light-matter interactions generally involve momentum exchange between incident photons and the target object giving rise to optical forces and torques. While typically weak, they become significant at the nanoscale, driving intense research interest in the exploitation of photon recoil to drive micro- and nanostructures. While great progress has been attained in controlling transversal degrees of freedom, three-dimensional movement remains challenging, particularly due to the impractical realization of pulling forces that oppose the direction of incident light. Here we theoretically present a novel nanomotor design that enables independent control over both transverse and longitudinal motion. This design exploits coupling between an azimuthally polarized Bessel beam and a dielectric glass cylinder to realistically achieve optical pulling forces. At the same time, asymmetric plasmonic dimers, embedded within the cylinder, provide lateral motion, through asymmetric scattering under plane wave illumination. We further demonstrate that unwanted displacements and rotations can be restrained, even at long illumination times. Our design unlocks a new degree of freedom in motion control, allowing for pulling, pushing, and lateral movement by simply tuning the polarization or switching between plane waves and Bessel beams.

Both the polarization state of coherent bichromatic fields produced by harmonic generation and a class of anisotropic paraxial optical cavities are examples of commensurate two-dimensional harmonic oscillators. The geometric phase for these systems is studied here, both in the classical/ray and quantum/wave regimes. The quantum geometric phase is described in terms of the coherent states of the system, for which recursive expressions are derived that yield the exact result and are numerically stable even for high modal orders.

[This corrects the article DOI: 10.1515/nanoph-2025-0140.].