Metalenses at visible wavelengths: Diffraction-limited focusing and subwavelength resolution imaging

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…

• NS
  National Science Foundation
• CS
  Charles Stark Draper Laboratory
• AF
  Agency for Science, Technology and Research
• MO
  Ministry of Science and Technology, Taiwan

  Award: 104-2917-I-564-058
• HS
  Harvard School of Engineering and Applied Sciences
• MU
  Multidisciplinary University Research Initiative

  Award: FA9550-14-1-0389
• AF
  Air Force Office of Scientific Research