Controllable plasmonic antennas with ultra narrow bandwidth based on silver nano-flags

We show theoretically plasmonic antennas based on two-step chemical synthesized silver nano-flags constructed by a silver nanowire and a nanoplate. The silver nano-flag antennas exhibit high polarization sensitivity and diversity of spectral signatures dependent on the structural parameters arising from the observed mode competition. With specific configuration engineering, the antennas show controllable electric-field enhancement and ultra narrow bandwidths down to about 2 nm. These nano-antennas promise exciting applications in lasing spaser, optical modulation, and enhanced nonlinear processes.