Abstract
Plasmonic metamaterials with artificial subwavelength structures are attracting much attention. Metal
nano-rods are typical plasmonic metamaterials and function as nanophotonic resonators. At the resonant
conditions in the visible and near-infrared regions, the electromagnetic waves at the resonant
wavelengths strongly couple with the nano-rods and are absorbed due to Joule and radiative losses.
Therefore, ultrasmall wavelength-selective absorbers can be made that consist of metal nano-rods. We
fabricated wavelength-selective optical attenuators, which are comprised of Au nano-rods that are
integrated with silicon waveguides for optical communications. The nano-rods and silicon waveguide
were fabricated on silicon-on-insulator substrates with micromachining technologies. An evanescent
wave of a propagating light into the silicon waveguide was coupled with a surface-plasmon-polariton
mode of the Au nano-rods at a resonant wavelength and efficiently absorbed. At a wavelength of 1565
nm, we observed optical attenuation of－17.7dB.
