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Proceedings Paper

Zero-index photonic crystal as low-aberration optical lens (Conference Presentation)
Author(s): Jian-Wen Dong; Xin-Tao He; Wei-Min Deng; Jia-Jun Yuan
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Paper Abstract

Fermionic Dirac cones have attracted tremendous attention in the electronic systems, such as topological insulator and graphene. As the classical analogs, photonic Dirac dispersions at the center of momentum space reveal a unique feature other than fermionic systems, i.e. zero-refractive-index behavior. In principle, such all-dielectric metamaterial is easily capable of scaling into optical wavelength, but it is seldom to address and promote to functional device with large area in silicon nanophotonics. Here, we show a prototype of large-area concave metalens consisting of silicon nanopillars array on silicon platform. The device was etched from n-type (100) single crystalline Si substrate by a top-down method. In theoretical prediction, such metalens can be modeled as a two-dimensional photonic crystal with conical bands at near-infrared wavelength. In this way, light focusing effect in the large-area metalens was observed directly through the out-of-plane scattering from the irregular substrate. The focal spot, which was very close to the curvature center of the metalens surface, indicated a little phase change of near-zero refractive index silicon photonic crystal. The effective refractive index retrieved from optical microscope images was quantitatively consistent with those from effective medium theory. The device performs as a near-aberration-free metalens near Dirac wavelength due to zero refractive index. Furthermore, it reveals a potential application for spectral detection based on wavelength-dependent effective index. The proposed strategy provides a feasible way for silicon-based application of zero-refractive-index photonic crystals.

Paper Details

Date Published: 9 November 2016
PDF: 1 pages
Proc. SPIE 9918, Metamaterials, Metadevices, and Metasystems 2016, 991822 (9 November 2016); doi: 10.1117/12.2237137
Show Author Affiliations
Jian-Wen Dong, Sun Yat-Sen Univ. (China)
Xin-Tao He, Sun Yat-Sen Univ. (China)
Wei-Min Deng, Sun Yat-Sen Univ. (China)
Jia-Jun Yuan, Sun Yat-Sen Univ. (China)

Published in SPIE Proceedings Vol. 9918:
Metamaterials, Metadevices, and Metasystems 2016
Nader Engheta; Mikhail A. Noginov; Nikolay I. Zheludev, Editor(s)

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