Flat metasurfaces to focus electromagnetic waves in reflection geometry.

We show that a flat metasurface with a parabolic reflection-phase distribution can focus an impinging plane wave to a point image in reflection geometry. Our system is much thinner than conventional geometric-optics devices and does not suffer the energy-loss issues encountered by many metamaterial devices working in transmission geometry. We designed realistic microwave samples and performed near-field scanning experiments to verify the focusing effect. Experimental results are in good agreement with full wave simulations, model calculations, and theoretical analyses.

[1]  J. Hao,et al.  An effective-medium model for high-impedance surfaces , 2007 .

[2]  D. Sievenpiper,et al.  High-impedance electromagnetic surfaces with a forbidden frequency band , 1999 .

[3]  Zhaowei Liu,et al.  Far-Field Optical Hyperlens Magnifying Sub-Diffraction-Limited Objects , 2007, Science.

[4]  L. Verslegers,et al.  Planar lenses based on nanoscale slit arrays in a metallic film , 2009, 2009 Conference on Lasers and Electro-Optics and 2009 Conference on Quantum electronics and Laser Science Conference.

[5]  Ann Roberts,et al.  Plasmonic lenses formed by two-dimensional nanometric cross-shaped aperture arrays for Fresnel-region focusing. , 2010, Nano letters.

[6]  Changbao Ma,et al.  Extraordinary light focusing and Fourier transform properties of gradient-index metalenses , 2011 .

[7]  Zhaowei Liu,et al.  A super resolution metalens with phase compensation mechanism , 2010 .

[8]  David R. Smith,et al.  Gradient index circuit by waveguided metamaterials , 2009 .

[9]  N. Yu,et al.  Light Propagation with Phase Discontinuities: Generalized Laws of Reflection and Refraction , 2011, Science.

[10]  M. Rahm,et al.  Metamaterial-based gradient index lens with strong focusing in the THz frequency range. , 2010, Optics express.

[11]  R. Shelby,et al.  Experimental Verification of a Negative Index of Refraction , 2001, Science.

[12]  Qiang Cheng,et al.  Controlling electromagnetic waves using tunable gradient dielectric metamaterial lens , 2008 .

[13]  David R. Smith,et al.  Spatial mapping of the internal and external electromagnetic fields of negative index metamaterials. , 2006, Optics express.

[14]  M. Rahm,et al.  Gradient index metamaterial based on slot elements , 2010, 1002.1025.

[15]  Xueqin Huang,et al.  A time-dependent Green's function approach to study the transient phenomena in metamaterial lens focusing , 2005 .

[16]  N. Fang,et al.  Sub–Diffraction-Limited Optical Imaging with a Silver Superlens , 2005, Science.

[17]  Shulin Sun,et al.  Gradient-index meta-surfaces as a bridge linking propagating waves and surface waves. , 2012, Nature materials.

[18]  David R. Smith,et al.  Extreme-angle broadband metamaterial lens. , 2010, Nature materials.

[19]  J. Pendry,et al.  Negative refraction makes a perfect lens , 2000, Physical review letters.