Optical properties of helical Ag nanostructures calculated by discrete dipole approximation method

The extinction spectra and field distribution of Ag helical nanostructures have been calculated using the discrete dipole approximation method. The plasmon peak of the Ag helix can be tuned not only by the structural parameters but also by the polarizations of the incident light, especially the circular polarizations. In addition, the polarization direction of the incident light can change the spatial distribution of the maximum E field, which provides a simple way to spatially resolve analyte's distribution on the nanostructures for sensing applications. (C) 2007 American Institute of Physics.