Broadband and high-efficiency accelerating beam generation by dielectric catenary metasurfaces

Abstract

<jats:title>Abstract</jats:title><jats:p>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.</jats:p>

Spin-decoupled metasurface for simultaneous detection of spin and orbital angular momenta via momentum transformation

“…The energy efficiency is limited for several reasons. First, owing to the fabrication defects, the measured diffraction efficiency of the fabricated metasurface is only ~30% (Section 6 of the Supplementary file), which can be further improved by optimizing the fabrication process and adopting semicontinuous metasurfaces 20 , 53 . Second, since the intensity is spread over a sort of V-shape with a cusp, the amount of energy focused on the specific spot of interest is ~16.3%.…”

Recent Progress on Ultrathin Metalenses for Flat Optics

“…Selecting the design of meta-atoms depends on a phase modulating mechanism which affects the phase and phase dispersion at each position (Shrestha et al, 2018;Chen et al, 2019d). Applying spatial multiplexing (Lin et al, 2016;Li et al, 2017;Arbabi et al, 2016c), cascading (McClung et al, 2020), or catenary (Pu et al, 2015;Zhang et al, 2020b), metasurfaces are widely used methods for achromatic focusing, and combining computational imaging with flat optics (Colburn et al, 2018) is also adopted for broadband phase modulating. Several metalenses that exploit resonance on dielectric (Aieta et al, 2015;Arbabi et al, 2017;Chen et al, 2018aChen et al, , 2018cWang et al, 2018) or plasmonic (Hu et al, 2016;Wang et al, 2017a;Hsiao et al, 2018) meta-atoms have been demonstrated.…”

Quasi-Continuous Metasurface Beam Splitters Enabled by Vector Iterative Fourier Transform Algorithm

“…Especially, asymmetric photonic spin-orbit interactions, enabled by the combination of the geometric phase and propagation phase, have shown great potential to achieve multifunctional devices and systems [ 7 , 8 ]. Different from the traditional metasurface that spatially tailors the geometries of the scatters to introduce the phase discontinuities [ 9 ], a quasi-continuous metasurface does not rely on numerous elaborately arranged elements to fulfill various functionalities [ 10 , 11 , 12 ]. A quasi-continuous metasurface beam splitter divides one laser beam into multiple beams and can be applied in structured light [ 13 , 14 , 15 , 16 ], optical interconnects [ 17 ], and camera calibration [ 18 , 19 ].…”