Event
MSE Seminar Series: Henri Lezek
Friday, April 18, 2014
1:00 p.m.-2:00 p.m.
Room 2110 Chemical and Nuclear Engineering Building
JoAnne Kagle
301 405 5240
jkagle@umd.edu
Plasmonic-Waveguide Metamaterials at Visible and Ultraviolet Frequencies
Henri J. Lezec
Center for Nanoscale Science and Technology, NIST
Predictions of exotic and potentially useful properties, such as a negative refractive index [1], have propelled the creation of materials with tailored electromagnetic responses under the form of metamaterials, artificial electromagnetic media structured on a deep-subwavelength scale [2]. Here, we focus on a novel class of three-dimensional (3D) metamaterials, based not on lithographically- patterned resonators, but on stacked, thin metal-dielectric plasmonic waveguides with smooth interfaces. Using this approach [3], we demonstrate a bulk metamaterial, based on Ag/TiO2 waveguides, having a negative-index electromagnetic response in the ultraviolet [4]. A flat slab of this metamaterial, designed with an isotropic refractive index n= -1, can act as a 3D Veselago flat lens [1] capable of projecting into free-space, beyond the near field, the image of arbitrary two- dimensional objects. We also show that unidirectional transmission of visible light can be provided by an ultra-thin structure combining subwavelength diffraction gratings and a pseudo-hyperbolic metamaterial, formed of stacked Ag/SiO2 plasmonic waveguides, which is engineered to display a sharp transmission window for incident electromagnetic waves having specific transverse spatial frequencies. Fabricated devices designed for operation at central wavelengths of 532nm and 633nm, respectively, display broadband, efficient asymmetric optical transmission with maximum contrast ratios exceeding 14dB.
[1] V.G. Veselago, Sov. Phys. Usp. 10 (1968). [2] C.M. Soukoulis, & M. Wegener, Nature Photon. 5 (2011). [3] E. Verhagen et al., Phys. Rev. Lett. 105 (2010). [4] T. Xu et al., Nature 497, (2013).
