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Self-accelerating beams show considerable captivating phenomena and applications owing to their transverse acceleration, diffraction-free and self-healing properties in free space. Metasurfaces consisting of dielectric or metallic subwavelength structures attract enormous attention to acquire self-accelerating beams, owing to their extraordinary capabilities in the arbitrary control of electromagnetic waves. However, because the self-accelerating beam generator possesses a large phase gradient, traditional discrete metasurfaces suffer from insufficient phase sampling, leading to a low efficiency and narrow spectral band. To overcome this limitation, a versatile platform of catenary-inspired dielectric metasurfaces is proposed to endow arbitrary continuous wavefronts. A high diffraction efficiency approaching 100% is obtained in a wide spectral range from 9 to 13 μm. As a proof-of-concept demonstration, the broadband, high-efficiency and high-quality self-accelerating beam generation is experimentally verified in the infrared band. Furthermore, the chiral response of the proposed metasurfaces enables the spin-controlled beam acceleration. Considering these superior performances, this design methodology may find wide applications in particle manipulation, high-resolution imaging, optical vortex generation, and so forth.

Considerable effort is devoted to research on reconfigurable beam focusing and optical cloaking in the basis of metamaterials/metasurfaces. However, it remains a great challenge to achieve multifunctional wavefront control on curved platforms, especially in the reflective case, which is of paramount importance in the emerging fields of active optics and stealth research. This study proposes a novel strategy to control the versatile reflective structured wavefront on a conformal platform by curving a flexible metasurface. This metasurface is fabricated in a high‐throughput manner by using ultra‐violet nano‐imprinting lithography (UV‐NIL), and its efficacy is verified through consistent simulated and experimental results. The conformal metasurface is designed to realize multifunctional performance by employing all‐metallic plasmonic structures based on the Pancharatnam‐Berry (PB) phase. A general theoretical scheme is also proposed for the projection of a curved surface onto a reference plane by a judicious compensation, combining the geometrical PB phase with curvature‐induced propagation phase. Moreover, as a proof‐of‐concept, curved metasurfaces with cylindrical shapes are experimentally characterized by their multifunctionalities in generating a beam spot with a continuously tunable focal length and reflecting plane waves used for camouflage, thereby confirming the feasibility and effectiveness of the proposed strategy. [ABSTRACT FROM AUTHOR]

Circular lens composed of annularly arranged metal nanoantennas is proposed to achieve far field superresolution focusing. Light illuminating on the nanoantennas' layer approximately acquires paraboloidal phase profile and then focuses into a spot. Lens constructed by monolayer nanoantennas achieve focusing with FWHM (full width at half maximum) of 924 nm and a focal length of 3385 nm, breaking the diffraction limit. Moreover, tri-layered lens realizes subwavelength focusing with FWHM of 320 nm (about 0.49 λ) and the field intensity of focus is optimized to 0.97 a.u. (arbitrary unit). Our proposal shows advances in focusing performance compared with previous work, making it promising in many applications, such as nanolithography, dense storage, and integrated optics. [ABSTRACT FROM AUTHOR]

Abstract: By using finite-difference-time-domain (FDTD) methods, transmission characteristics and field distribution profile of the aperture-coupled rectangular resonators are investigated in metal–insulator–metal (MIM) waveguide system. Simulation results indicate the aperture affects resonant modes of the rectangular cavity in different manner when the aperture is shifting along the rectangular cavity. Moreover, resonant modes can be selectively suppressed when the aperture locates at nodes of the magnetic field. Consequently, different transmission spectra and dip-wavelength can be obtained even with the same resonator length, which provides an additional degree to tailor the system response in the nanoscale. In addition, flexible resonance wavelength ratio and tunable free spectral range (FSR) can be obtained compared with conventional Fabry–Perot filter whose resonance wavelength ratio is approximately equal to 1:1/2:1/3 due to the limitation by the Fabry–Perot resonance. [Copyright &y& Elsevier]