Subwavelength resolution imaging requires high numerical aperture (NA) lenses, which are bulky and expensive. Metasurfaces allow the miniaturization of conventional refractive optics into planar structures. We show that high-aspect-ratio titanium dioxide metasurfaces can be fabricated and designed as metalenses with NA = 0.8. Diffraction-limited focusing is demonstrated at wavelengths of 405, 532, and 660 nm with corresponding efficiencies of 86, 73, and 66%. The metalenses can resolve nanoscale features separated by subwavelength distances and provide magnification as high as 170×, with image qualities comparable to a state-of-the-art commercial objective. Our results firmly establish that metalenses can have widespread applications in laser-based microscopy, imaging, and spectroscopy.
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http://dx.doi.org/10.1126/science.aaf6644 | DOI Listing |
Adv Mater
November 2024
Zhejiang Key Laboratory of 3D Micro/Nano Fabrication and Characterization, School of Engineering, Westlake University, 18 Shilongshan Road, Hangzhou, 310030, China.
Enhancing energy density and efficiency in laser processing hinges on precise beam focusing, yet this often causes severe heat absorption and focus shifts in optical lenses. Traditional cooling methods increase cost and complexity, severely limiting versatility. Here, monolithic silicon carbide (SiC) metalens is introduced, which shows unparalleled thermal stability, integrated with a high-power laser.
View Article and Find Full Text PDFThis study introduces a novel meta-fiber design that combines single-mode fibers with thermally expanded cores and nano-printed high numerical aperture metalenses. These advanced meta-fibers feature enlarged mode field diameters, offering improved mechanical stability, reduced environmental sensitivity and simplified metalens design by minimizing wavefront curvature. The concept's validity is confirmed through high numerical aperture metalenses, nanoprinted onto thermally expanded core fibers, demonstrating diffraction-limited focusing up to a numerical aperture of 0.
View Article and Find Full Text PDFThe advanced Kirkpatrick-Baez (AKB) mirror setup is an effective and compelling solution to provide stable X-ray nano-focusing for synchrotron radiation or free-electron laser beamlines. We propose an AKB mirror design optimization approach to mitigate the difficulties associated with mirror fabrication by minimizing the total slope ranges of the four curved mirrors while achieving the expected focusing performance. In the optimization, we have considered geometry constraints to ensure the beam acceptance with the required clear aperture, the diffraction-limited focal size with the adequate numerical aperture, and the desired mirror gaps for adjustment and the necessary working distance for the sample stage.
View Article and Find Full Text PDFNat Commun
November 2024
Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania, USA.
Achieving achromaticity across the visible light spectrum is crucial for metalenses in imaging systems. Single-layer metalenses struggle with weak focusing power or small aperture sizes due to inadequate group delay control. Multilayer metalenses offer some improvement but come with increased design and fabrication complexity.
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