Low-Contrast Dielectric Metasurface Optics

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• 作者：Alan Zhan ; Shane Colburn ; Rahul Trivedi ; Taylor K. Fryett ; Christopher M. Dodson ; Arka Majumdar
• 刊名：ACS Photonics
• 出版年：2016
• 出版时间：February 17, 2016
• 年：2016
• 卷：3
• 期：2
• 页码：209-214
• 全文大小：583K
• ISSN：2330-4022

文摘

The miniaturization of current image sensors is largely limited by the volume of the optical elements. Using a subwavelength-patterned quasi-periodic structure, also known as a metasurface, one can build planar optical elements based on the principle of diffraction. Recent demonstrations of high-quality metasurface optical elements are mostly based on high-refractive-index materials. Here, we present a design of low-contrast metasurface-based optical elements. We fabricate and experimentally characterize several silicon nitride-based lenses and vortex beam generators. The fabricated lenses achieved beam spots of less than 1 μm with numerical apertures as high as ∼0.75. We observed a transmission efficiency of 90% and focusing efficiency of 40% in the visible regime. Our results pave the way toward building low-loss metasurface-based optical elements at visible frequencies using low-contrast materials and extend the range of prospective material systems for metasurface optics.