Silica nanowires: manipulating light at the nanoscale

Can light be guided by a fiber whose diameter is much smaller than the wavelength of the light? Can we mold the flow of light on the micrometer scale so it wraps, say, around a hair? Until recently the answer to these questions was ‘no’. We developed a technique for drawing long, free-standing silica wires with diameters down to 20 nm that have a surface smoothness at the atomic level and a high uniformity of diameter. Light can be launched into these silica nanowires by optical evanescent coupling and the wires allow low-loss single-mode operation. They can be bent sharply, making it possible to control the propagation of light around micrometer-sized corners, and can be used to couple light into single semiconductor nanowires. The nanowires have applications in microphotonic devices for optical processing and environmental sensing. We will present two recent results obtained with these nanowires: the generation of supercontinuum light with very low energy femtosecond laser pulses and the couple of light into single ZnO nanowire waveguides.