Plasmonic Luneburg and Eaton lenses.
Plasmonics takes advantage of the properties of surface plasmon polaritons, which are localized or propagating quasiparticles in which photons are coupled to the quasi-free electrons in metals. In particular, plasmonic devices can confine light in regions with dimensions that are smaller than the wavelength of the photons in free space, and this makes it possible to match the different length scales associated with photonics and electronics in a single nanoscale device. Broad applications of plasmonics that have been demonstrated to date include biological sensing, sub-diffraction-limit imaging, focusing and lithography and nano-optical circuitry. Plasmonics-based optical elements such as waveguides, lenses, beamsplitters and reflectors have been implemented by structuring metal surfaces or placing dielectric structures on metals to manipulate the two-dimensional surface plasmon waves. However, the abrupt discontinuities in the material properties or geometries of these elements lead to increased scattering of surface plasmon polaritons, which significantly reduces the efficiency of these components. Transformation optics provides an alternative approach to controlling the propagation of light by spatially varying the optical properties of a material. Here, motivated by this approach, we use grey-scale lithography to adiabatically tailor the topology of a dielectric layer adjacent to a metal surface to demonstrate a plasmonic Luneburg lens that can focus surface plasmon polaritons. We also make a plasmonic Eaton lens that can bend surface plasmon polaritons. Because the optical properties are changed gradually rather than abruptly in these lenses, losses due to scattering can be significantly reduced in comparison with previously reported plasmonic elements.
NSF Nanoscale Science and Engineering Center, 3112 Etcheverry Hall, University of California, Berkeley, California 94720, USA.
Thomas
T
Zentgraf
Yongmin
Y
Liu
Maiken H
MH
Mikkelsen
Jason
J
Valentine
Xiang
X
Zhang
D003198:Computer Simulation; D004583:Electrons; D004867:Equipment Design; D006046:Gold / Q000737:chemistry*; D007909:Lenses; D008027:Light; D018625:Microscopy, Atomic Force / Q000379:methods; D008855:Microscopy, Electron, Scanning / Q000379:methods; D036103:Nanotechnology / Q000295:instrumentation* / Q000379:methods; D055095:Optics and Photonics / Q000295:instrumentation; D017785:Photons; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D012542:Scattering, Radiation; D020349:Surface Plasmon Resonance / Q000295:instrumentation* / Q000379:methods
D006046:Gold; D019904:Polymethyl Methacrylate
Opt Express. 2010 Jul 19;18(15):15757-68
20720959
Nat Nanotechnol. 2008 Dec;3(12):733-7
19057593
Opt Lett. 2005 Apr 15;30(8):893-5
15865390
Nat Mater. 2009 Jul;8(7):568-71
19404237
Nature. 2003 Aug 14;424(6950):824-30
12917696
Nature. 2009 Oct 1;461(7264):629-32
19718019
Phys Rev Lett. 2001 Apr 2;86(14):3008-11
11290094
Science. 2006 Nov 10;314(5801):977-80
17053110
Phys Rev Lett. 2005 Feb 11;94(5):057401
15783692
Science. 2006 Jun 23;312(5781):1780-2
16728597
Science. 1997 Feb 21;275(5303):1102-6
9027306
Nano Lett. 2007 Jun;7(6):1697-700
17500579
Nat Mater. 2010 Feb;9(2):129-32
20023631
Nature. 2006 Mar 23;440(7083):508-11
16554814
Nano Lett. 2010 Jul 14;10(7):2574-9
20518545
Science. 2006 Jun 23;312(5781):1777-80
16728596
Nano Lett. 2010 Jun 9;10(6):1991-7
20465268
Opt Express. 2010 Sep 27;18(20):20610-9
20940955
Science. 2007 Sep 21;317(5845):1698-702
17885123
Nano Lett. 2010 Jun 9;10(6):1985-90
20465271
Adv Mater. 2010 Jun 18;22(23):2561-4
20446302
Phys Rev Lett. 2004 Sep 24;93(13):137404
15524758
Science. 2005 Apr 22;308(5721):534-7
15845849