All-optical active switching in individual semiconductor nanowires

The imminent limitations of electronic integrated circuits are stimulating intense activity in the area of nanophotonics for the development of on-chip optical components(1), and solutions incorporating direct-bandgap semiconductors are important in achieving this end(2). Optical processing of data(3) at the nanometre scale is promising for circumventing these limitations, but requires the development of a toolbox of components including emitters, detectors, modulators, waveguides and switches. In comparison to components fabricated using topdown methods, semiconductor nanowires offer superior surface properties(4) and stronger optical confinement(5). They are therefore ideal candidates for nanoscale optical network components(6), as well as model systems for understanding optical confinement(7). Here, we demonstrate all-optical switching in individual CdS nanowire cavities with subwavelength dimensions through stimulated polariton scattering, as well as a functional NAND gate built from multiple switches. The device design exploits the strong light-matter coupling present in these nanowires, leading to footprints that are a fraction of those of comparable silicon-based dielectric contrast(8,9) and photonic crystal(10,11) devices.