Plasmonic extraordinary transmittance in array of metal nanorods

The optical response of an array of metal nanorods is studied in the case when the cylinders almost touch by their generatrices. As the cylinders approach each other, a series of surface plasmon resonances are excited. The first longitudinal mode is different from the higher-order lateral modes. The lateral resonances occur near the frequency where the real part of the metal permittivity changes sign. The plasmon resonances result in maxima and minima in the reflectance and transmittance. The resonances also result in a huge enhancement of the local electric field in the gap between cylinders.