Binary-nanoparticle left-handed metamaterial for optical frequencies

摘要

We show that metamaterial constituted from periodic array of identical noble-metal binary nanoparticles embedded into dielectric host matrix can exhibit left-handed properties in optical frequency domain. In contrast to recent suggestions to use, for example, double periodic lattice of metal nanowires or lattice of nanoparticle loops (or necklaces) binary-nanoparticle material utilizes lowest plasmonic eigenmodes (dipole and quadropole) providing necessary electric and magnetic responses in the system of binary particles. This makes possible to extend negative refraction region due to increasing of the corresponding resonances quality-factors in comparison to high multipole modes excited in nanoparticle necklaces. Using the well-known optical constants for noble metals we calculate the optical response of binary-particle metamaterials for silver, gold and copper in the wavelength range 350-1200nm. We find that silver is the most suitable material for the particles which provides left-handed properties of metamaterial for approximately 400-1100nm wavelengths (at different values of permittivity of the host) whereas the gold particles can lead to the negative refraction only in more narrow range 750-1 l00nm because of the greater losses in the particles. Copper nanoparticle array seems to be unable to produce left-handed metamaterial at all.