Negative refractive indices of a confined discrete fishnet metamaterial at visible wavelengths

A left-handed material, a discrete fishnet array confined in a metal waveguide, is reported in our work. Our simulation results show the negative refraction occurring at visible wavelengths. The maximum of a FOM=-Re(n)/Im(n) reaches 0.9 near the wavelength of 640 nm. For another set of dimensions of the unit cell, the maximum of a FOM equals 1.07 near the 655 nm wavelength. It is indicated that this approach is greatly effective for the realization of negative refraction at visible wavelengths. Moreover, the mechanism of resonance as well as the effective inductor-capacitor (LC) circuit model is investigated. (C) 2008 Optical Society of America