TUNABLE AND ACTIVE OPTICAL NEGATIVE INDEX METAMATERIALS

Optical negative-index metamaterials (NIMs) have attracted a significant amount of research attention because of their unique properties and important applications including superlenses and cloaking. Recently, after numerous fundamental studies, research interest has turned to the realization of real NIM applications. These applications are strongly limited by the long and fixed working wavelength and the significant losses in NIM designs. In this chapter, we demonstrate our recent progress in the design, fabrication, and characterization of optical NIMs. First, we demonstrate NIMs operating in optical wavelength range. Then we show a method to adjust the refractive index of dielectric layers in a NIM and thereby tune the resonant wavelength of NIM by tens of nanometers. Finally, and most importantly for real-world NIM applications, we introduce active materials into NIMs and show that loss compensation can significantly improve the essential parameters of NIMs. We believe our studies will be very interesting and promising for real NIM applications in the near future.