A negative permeability material at red light

Hsiao-Kuan Yuan, Purdue University - Main Campus
Uday K. Chettiar, Purdue University
Wenshan Cai, Purdue University - Main Campus
Alexander V. Kildishev, Birck Nanotechnology Center, Purdue University
Alexandra Boltasseva, Birck Nanotechnology Center, Purdue University
V. P. Drachev, Birck Nanotechnology Center, School of Electrical and Computer Engineering, Purdue University
V. M. Shalaev, Birck Nanotechnology Center and School of Electrical and Computer Engineering, Purdue University

Abstract

A negative permeability in a periodic array of pairs of thin silver strips is demonstrated experimentally for two distinct samples. The effect of the strip surface roughness on negative permeability is evaluated. The first sample, Sample A, is fabricated of thinner strips with a root mean square roughness of 7 nm, while Sample B is made of thicker strips with 3-nm roughness. The real part of permeability, mu', is -1 at a wavelength of 770 nm in Sample A and -1.7 at 725 nm in Sample B. Relative to prototypes simulated with ideal strips, larger strip roughness acts to decrease vertical bar mu'vertical bar by a factor of 7.8 in Sample A versus a factor of 2.4 decrease for Sample B.