Institut Fresnel, CNRS, Aix-Marseille Université, Domaine Universitaire de Saint-Jérôme, Service 161, 13397 Marseille Cedex 20, France
State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, P.R. China
Pohl Institute of Solid State Physics, Tongji University, Shanghai 200092, P.R. China
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.
(Received January 30 2008)
(Revised March 26 2008)
(Accepted April 2 2008)
(Online publication July 25 2008)