META 2021, META'12

Font Size: 
Chiral Surface Plasmon Polaritons on Metallic Nanowires
Hongxing Xu

Last modified: 2011-12-05


The interaction of chiral micro- and nano-objects with circular polarized light is a topic of fundamental interest in various scientific fields. Since surface plasmon polaritons (SPPs) can overcome the diffraction limit of light, enabling the manipulation of light at the nanometer scale, three dimensional chiral plasmonic nanostructures are a topic of intensive current interest. Here, we show that chiral SPPs can be generated by linearly polarized light incident at the end of a nanowire with cylindrical symmetry, whose structure is not chiral at all, exciting a coherent superposition of three specific nanowire waveguide modes. Rather, the chirality is accomplished by the superposition of low-order surface plasmon modes (m = 0 and m = ±1) with a λ/2 phase delay excited by linearly polarized light at one end of the nanowire. With quantum-dot-based fluorescence imaging, the chiral SPPs can be clearly observed on the nanowires. Interestingly, the chirality of the SPPs is still preserved in the emitted photons at the distal end of the nanowire, which makes a nanowire as a broad bandwidth subwavelength λ/4 converter of the linearly polarized input light. This discovery may create new opportunities for the design of nanoscale integrated photonic components, and provides a subwavelength circular polarized light source that may be useful as a local probe of enantiomeric molecules and other reduced-symmetry nanoscale systems.