Nanowire plasmonic waveguides, circuits and devices

As typical one-dimensional nanostructures for waveguiding tightly confined optical fields beyond the diffraction limit, metal nanowires have been used as versatile nanoscale building blocks for functional plasmonic and photonic structures and devices. Metal nanowires, especially those fabricated by bottom-up synthesis such as Ag and Au nanowires, usually exhibit excellent diameter uniformity and surface smoothness with diameters down to tens of nanometers, which offers great opportunities for plasmonic waveguiding of optical fields with deep-subwavelength confinement, coherence maintenance and low scattering losses. Based on nanowire plasmonic waveguides, a variety of applications ranging from plasmonic couplers, interferometers, resonators to photon emitters have been reported in recent years. In this article, significant progresses in these nanowire plasmonic waveguides, circuits and devices are reviewed. Future outlook and challenges are also discussed.