Planar Lenses at Visible Wavelengths

Abstract

Sub-wavelength 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 meta-lenses with NA = 0.8. Diffraction-limited focusing is demonstrated at wavelengths of 405 nm, 532 nm, and 660 nm with corresponding efficiencies of 86%, 73%, and 66%. The meta-lenses can resolve nanoscale features separated by sub-wavelength distances and provide magnification as high as 170x with image qualities comparable to a state-of-the-art commercial objective. Our results firmly establish that meta-lenses can have widespread applications in laser-based microscopy, imaging, and spectroscopy.

References in corpus (4)

• Aberration-free ultra-thin flat lenses and axicons at telecom wavelengths based on plasmonic metasurfaces
• Subwavelength-thick Lenses with High Numerical Apertures and Large Efficiency Based on High Contrast Transmitarrays
• High efficiency dielectric metasurfaces at visible wavelengths
• Flat Dielectric Grating Reflectors with High Focusing Power