Non-linear femtosecond optics and waveguiding in single zincoxide nanowires

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In the last years it has become possible to reproducibly fabricate single-crystalline nanowires of the wide-bandgap semiconductor ZnO possessing diameters between 50-200nm and lengths of typically 10-20¿m. Whereas these nanowires are too large to show quantum mechanical confinement effects they offer unique optical properties since their diameter is usually smaller than the wavelength of light in the visible spectral range. Due to their high crystalline quality they possess planar facets at their end sides and extremely smooth side walls which make them naturally act as resonators and waveguides for optical modes. This research project aims at the investigation of these special optical properties by use of ultrashort laser pulses. Due to their high peak intensity strong non-linear interactions of the light field with the semiconductor nanowire are expected. Silica nanowires prepared by a self-modulated taper-drawing technique will be used to inject femtosecond pulses into ZnO nanowires and to detect the photoluminescence of the wire as well as the pulses after transmission through the wire. Thus, the waveguiding properties of the wires, the evanescent coupling between closely spaced wires, the strong evanescent coupling to surrounding gases and materials, and strong non-linear effects are expected to occur and will be investigated.