Geometrical optimization of nanostrips for surface plasmon excitation: an analytical approach.

We give a simple tool for the optimization of the dimensions of a metallic nanostrip illuminated at a given wavelength under normal incidence, to get a maximum of the electromagnetic field amplitude in the nanostrip. We propose an analytical formula that gives the widths and heights of the series of nanostrips that produce field enhancement. The validity of the analytical formula is checked by using the finite element method. This design of a nanostrip could be useful for sensors and thermally active components.