Transformation of the Surface Plasmons on Nanometallic Rod Array to Tunable Light Radiation

We propose and investigate the transformation of the surface plasmons (SPs) on the nanometallic cylindrical rod array to tunable light radiation via an exotic Smith-Purcell effect. The electron beam exciting SPs on a single nanometal rod, a pair of rods, and rod array were discussed. The requirements for them to transform into radiation were then explored. The radiation has higher intensity and better coherence than the ordinary Smith-Purcell radiation (SPR). The array of rod pair can get radiation with even higher intensity due to the excitation of gap SP modes. By adjusting the rod diameter or the gap width between the rods, the radiation frequency and intensity can be well tuned.