Non-linear femtosecond optics and waveguiding in single zincoxide nanowires

在过去的几年中，已经可以重复制造具有直径在50- 200 nm之间，长度通常为10-20 μ m的宽带隙半导体ZnO的单晶纳米线。尽管这些纳米线太大而不能显示量子力学限制效应，但它们提供了独特的光学性质，因为它们的直径通常小于可见光谱范围内的光的波长。由于它们的高结晶质量，它们在其端侧具有平面刻面和极其光滑的侧壁，这使得它们自然地充当光学模式的谐振器和波导。本研究计划旨在利用超短激光脉冲来研究这些特殊的光学性质。由于它们的高峰强度，预期光场与半导体纳米线的强非线性相互作用。通过自调制锥形拉伸技术制备的二氧化硅纳米线将被用于将飞秒脉冲注入ZnO纳米线，并检测线的光致发光以及通过线传输后的脉冲。因此，预期将发生并将研究导线的波导特性、紧密间隔的导线之间的倏逝波耦合、与周围气体和材料的强倏逝波耦合以及强非线性效应。

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.