Calculating nonlocal optical properties of metallic nanowires with FDTD method

We present a FDTD method which can be used to calculate the optical properties of nanostructures with nonlocal effect. The effect can be described by a spatially nonlocal dielectric function with a Drude plus two Lorentz terms model. We compared the optical properties of isolated nanowires with different radii. According to the extinction spectra, we can determine in which length scale the nonlocal effects become remarkable and should be taken into consideration in real applications. At the same time, we verify the conclusions by the transmission of nanostructures. Our method and related results can be used as a tool and reference in the design of realistic sub-wavelength devices.