  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 broad-band 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 broad-band high-throughput near-field optical
microscope.
