Highly efficient interfacing of guided plasmons and photons in nanowires

Successful exploitations of strongly confined surface plasmon-polaritons critically rely on their efficient and rapid conversion to lossless channels. We demonstrate a simple, robust, and broadband butt-coupling technique for connecting a metallic nanowire and a dielectric nanofiber. Conversion efficiencies above 95% in the visible and close to 100% in the near-infrared can be achieved with realistic parameters. Moreover, by combining butt-coupling with nanofocusing, we propose a broadband high-throughput near-field optical microscope.