Freestanding optical negative-index metamaterials of green light

A freestanding, multilayered fishnet metamaterial is reported to experimentally exhibit a negative refractive index in the green-light spectral range. The realization of a negative refractive index at such a high frequency range mainly originates from low-loss magnetic resonance and interactions between the neighboring functional layers. Based on a good agreement between the numerically simulated and experimentally measured transmittance and reflectance spectra, a single negative refractive index of -0.76 with a figure-of-merit of 0.5 is achieved for the metamaterial at the wavelength of 532 nm.