Low-Contrast Dielectric Metasurface Optics Article Swipe
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· 2016
· Open Access
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· DOI: https://doi.org/10.1021/acsphotonics.5b00660
· OA: W1869061657
The miniaturization of current image sensors is largely limited by the volume\nof the optical elements. Using a sub-wavelength patterned quasi-periodic\nstructure, also known as a metasurface, one can build planar optical elements\nbased on the principle of diffraction. However, it was believed that high\nrefractive index materials are required for metasurface optics. Here, we show\nthat one can employ the design principles of a metasurface even with low\ncontrast materials, such as silicon nitride. We validate our theory by\nfabricating and experimentally characterizing several silicon nitride based\nlenses and vortex beam generators . The fabricated lenses achieved beam spots\nof less than 1 {\\mu}m with numerical apertures as high as ~ 0.75. A\ntransmission efficiency of 90% and focusing efficiency of 40% in the visible\nregime was observed. Our results pave the way towards building low-loss\nmetasurface based optical elements at visible frequencies using low contrast\nmaterials.\n
