The optical properties of windmill-shaped nanostructures

The optical properties of the windmill-shaped nanostructures, composed of four non-connected mutual perpendicular nanorods, are calculated by the discrete dipole approximation method. The results show that the cascade electric field (E field) enhancements occur at the lateral surface of the nanorods. Although the E field distributions vary with the incident polarizations, much enhanced E fields always occur between the lateral surface of one nanorod and the tip of its perpendicular nanorod. Therefore, when the windmill-shaped nanostructures work as the substrates for surface enhanced Raman (SERS) scattering, the SERS intensities would be less dependent on the incident polarizations. In addition, the main plasmon peaks of the windmill-shaped nanostructures can be tuned by changing their structural parameters. These results would be of great significance for engineering larger intensity SERS substrates.