Nanophotonics (Berlin, Germany)最新文献

Under-display camera (UDC) systems enable full-screen displays in smartphones by embedding the camera beneath the display panel, eliminating the need for notches or punch holes. However, the periodic pixel structures of display panels introduce significant optical diffraction effects, leading to imaging artifacts and degraded visual quality. Conventional approaches to mitigate these distortions, such as deep learning-based image reconstruction, are often computationally expensive and unsuitable for real-time applications in consumer electronics. This work introduces an inverse-designed metasurface for wavefront restoration, addressing diffraction-induced distortions without relying on external software processing. The proposed metasurface effectively suppresses higher-order diffraction modes caused by the metallic pixel structures, restores the optical wavefront, and enhances imaging quality across multiple wavelengths. By eliminating the need for software-based post-processing, our approach establishes a scalable, real-time optical solution for diffraction management in UDC systems. This advancement paves the way to achieve software-free real-time image restoration frameworks for many industrial applications.

We present a systematic investigation of the optical response to circularly polarized illumination in twisted stacked plasmonic nanostructures. The system consists in two identical, parallel gold triskelia, centrally aligned and rotated at a certain angle relative to each other. Sample fabrication was accomplished through a novel multilevel high-resolution electron beam lithography. This stack holds two plasmonic modes of multipolar character in the near-infrared range, showing a strong dependence of their excitation intensities on the handedness of the circularly polarized incident light. This translates into a large circular dichroism which can be modulated by adjusting the twist angle of the stack. Fourier-transform infrared (FTIR) spectroscopy and numerical simulations were employed to characterize the spectral features of the modes. Remarkably, in contrast to previous results in other stacked nanostructures, the system's response exhibits a behavior analogous to that of two interacting dipoles only at small angles. As the angle approaches 15°, where maximum dichroism is observed, more complex modes of the stack emerge. These modes evolve towards two in-phase multipolar excitations of the two triskelia as the angle increases up to 60°. Finally, simulations for a triangular array of such stacked elements show a sharp mode arising from the hybridization of a surface lattice resonance with the low-energy mode of the stack. This hybridized mode demonstrates the capability to be selectively switched on and off through the light polarization handedness.

[This corrects the article DOI: 10.1515/nanoph-2020-0087.].

This study focuses on the optical heating of spatially dispersive solids due to electronic light scattering (ELS), a phenomenon driven by indirect optical transitions. In this process, a light-illuminated spatial heterogeneity generates an optical near-field photon with expanded momentum and thereby electron-photon momentum matching can be fulfilled. It results in indirect optical transitions which contribute to broadband inelastic emission, a physical process known as electronic light scattering or Compton scattering of visible photons. This is followed by thermalization of the electron system, making the solids to heat up and eventually melt. We experimentally demonstrate this effect by optical melting a spatially confined semiconductor (Si) and metal (Au) under moderate continuous-wave laser illumination with the intensity of only a few MW/cm². We claim that ELS represents the dominant physical mechanism governing the interaction of light with spatially dispersive media, underpinning a broad range of thermo-optical phenomena and applications.

Photonic integrated circuits (PICs) are transforming optical technology by miniaturizing complex photonic elements and systems onto single chips. However, scaling PICs to higher densities is constrained by optical crosstalk and device separation requirements, limiting both performance and size. Recent advancements in anisotropic metamaterials, particularly subwavelength gratings (SWGs), address these challenges by providing unprecedented control over evanescent fields and anisotropic perturbations in PICs. Here we review the role of anisotropic SWG metamaterials in enhancing integration density, detailing two foundational mechanisms - skin depth engineering and anisotropic perturbation - that mitigate crosstalk and enable advanced modal controls. We summarize their applications within four key functions: confinement manipulation, hetero-anisotropy and zero-birefringence, adiabatic mode conversion, and group velocity and dispersion control, showing how each benefits from distinct SWG properties. Finally, we discuss current limitations and future directions to expand the full potentials of anisotropic SWG metamaterials, toward highly dense and scalable PICs.

[This corrects the article DOI: 10.1515/nanoph-2023-0708.].

Second-harmonic generation (SHG) facilitated by plasmonic nanostructures has drawn considerable attention, owing to its efficient frequency up-conversion at the nanoscale and potential applications in on-chip integration and nanophotonic devices. Herein, we present a nanodimer array fabricated by nanoimprinting, composed of nanofinger-pair symmetrically leaning at an off-angle with a well-defined sub-nanometric gap. Commonly, geometric symmetry would suppress the far-field SHG due to the near-field cancelling of symmetric surface SH polarization. However, we find that the light-induced surface SH polarization distribution along the wave-vector of incidence could be influenced by the off-angle, which is consistent to the requirement of SH polarization symmetry-breaking in symmetric metallic nanocavity. A dramatic enhancement of far-field SHG is achieved by tuning the off-angle of nanofinger-pair, even approaching up to over 4 orders of magnitude for an optimal value. The demonstration of SHG enhancement on our well-defined plasmonic nanodimer provides a new way of on-chip integration to activate high-efficient SH radiation, which might be potential for applications in novel nonlinear optical nanodevices with remarkable efficiency and sensitivity.