Issue Eur. Phys. J. Appl. Phys. Volume 46, Number 3, June 2009 Metamaterials Article Number 32603 Number of page(s) 6 Section Metamaterials 2007 DOI 10.1051/epjap:2008148 Published online 25 July 2008

Eur. Phys. J. Appl. Phys. 46, 32603 (2009)
DOI: 10.1051/epjap:2008148

Compensation of loss to approach –1 effective index by gain in metal-dielectric stacks

J. Zhang^{1, 2}, H. Jiang^{1, 3}, B. Gralak¹, S. Enoch¹, G. Tayeb¹ and M. Lequime<sup>1

1</sup>  Institut Fresnel, CNRS, Aix-Marseille Université, Domaine Universitaire de Saint-Jérôme, Service 161, 13397 Marseille Cedex 20, France
²  State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, P.R. China
³  Pohl Institute of Solid State Physics, Tongji University, Shanghai 200092, P.R. China

stefan.enoch@fresnel.fr

Received: 30 January 2008 / Received in final form: 26 March 2008 / Accepted: 2 April 2008 / Published online: 25 July 2008

Abstract
We propose a theoretical study of optimization of metal-dielectric multilayer in order to approach -1 effective refractive index for transverse magnetic waves and a wavelength in the visible. The absorption losses of metal appear to be a crucial factor that affects the effective properties of the multilayer. Taking advantage of the dispersion relation of Bloch modes, we show that the losses not only decrease the transmission of the stack, but also change the negatively refracted angle. Then, we propose that using a gain-providing semiconductor (GaN) may allow compensating for the losses in metal layers. In theory, the performances of the structure can be improved greatly when gain is involved. When considering finite thickness structures, and with appropriate thickness for the terminating layers, it is possible to obtain a high transmission of the structure. A near -1 effective index metal-dielectric stack with high transmission may pave the way to the realization of negative quasi-isotropic refraction in the visible or ultraviolet wavelength range.

PACS
42.25.-p - Wave optics.
78.66.Bz - Metals and metallic alloys.
78.67.Pt - Multilayers; superlattices.

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