Surface Effects and Pump-Probe Studies of Nanowire Waveguides

由氧化锌（ZnO）制成的纳米线和纳米棒是未来在近紫外光谱区工作的光电器件的有前途的构建块。通过气相外延（VPE），可以在不同的衬底上生长具有优异光学质量和仔细可调长度和直径的纳米棒。一种新的低温技术，使用水化学生长（ACG）的大规模纳米棒阵列的制造提供了迷人的可能性，如使用柔性塑料基板。本计画将系统地分析ACG与VPE在不同基底上所成长奈米棒系综之线性与非线性光学性质。重点将放在使用透明基板上的纳米棒样品作为高效率的非线性光学器件，如倍频器的可能性。时间分辨测量将提供洞察ACG纳米棒在脉冲光激发下发生的微观过程，到目前为止还没有在文献中得到解决。这些实验应该特别解释这种新材料的光学性质的表面状态的作用和性质。最后，它将实验分析，如果使用ACG在金属层上的纳米棒的生长降低了在这样的设备中的激光阈值，从而允许在光泵浦下的有效的相干激光发射。

Nanowires and nanorods made of zincoxide (ZnO) are promising building blocks for future optoelectronic devices operating in the near-UV spectral region. By vapour-phase epitaxy (VPE) nanorods with excellent optical quality and carefully adjustable lengths and diameters can be grown on different substrates. A new low-temperature technique which uses aqueous chemical growth (ACG) for the fabrication of large-scale nanorod arrays provides fascinating possibilities like using flexible plastic substrates. In this project the linear and non-linear optical properties of nanorod ensembles grown by ACG and VPE on different substrates will be systematically analyzed. Emphasis will be put on the possibility of using nanorod samples on transparent substrates as highly efficient non-linear optical devices like frequency doublers. Time-resolved measurements will provide insight into the microscopic processes occurring in ACG nanorods under pulsed optical excitation which up to now have not been addressed in the literature. These experiments should especially explain the role and nature of surface states for the optical properties of this new kind of material. Finally, it will be experimentally analyzed if the growth of nanorods using ACG on metallic layers decreases the lasing threshold in such devices thus allowing for efficient coherent laser emission under optical pumping.