Absorptive lasing mode suppression in ZnO nano- and microcavities
Absorptive lasing mode suppression in ZnO nano- and microcavities
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DOI：
10.1063/1.4960660
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发表时间：
2016-08
影响因子：
4
通讯作者：
M. Wille;T. Michalsky;E. Krüger;M. Grundmann;R. Schmidt‐Grund
中科院分区：
文献类型：
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作者：
M. Wille;T. Michalsky;E. Krüger;M. Grundmann;R. Schmidt‐Grund
我们最终解释了我们观察到的和文献报道的 ZnO 纳米和微腔中不同的激光模式能量。通常使用的激发激光器的有限穿透深度会导致不均匀的空间增益区域，具体取决于结构尺寸和几何形状。因此，激发后仍然存在弱激发甚至非激发区域，其中模式立即被激子吸收抑制。我们比较了室温下 ZnO 微米线、纳米线和类四足结构的效应，并证明相应的模式选择效应对于具有六边形横截面的微米线中的回音壁模式最为明显。此外，通过将激发激光的光斑尺寸与单根 ZnO 纳米线的激光模式特性相关联，可以证明吸收激光模式的抑制。
We conclusively explain the different lasing mode energies in ZnO nano- and microcavities observed by us and reported in literature. The limited penetration depth of usually used excitation lasers results in an inhomogeneous spatial gain region depending on the structure size and geometry. Hence, weakly or even nonexcited areas remain present after excitation, where modes are instantaneously suppressed by excitonic absorption. We compare the effects for ZnO microwires, nanowires, and tetrapod-like structures at room temperature and demonstrate that the corresponding mode selective effect is most pronounced for whispering-gallery modes in microwires with a hexagonal cross section. Furthermore, the absorptive lasing mode suppression will be demonstrated by correlating the spot size of the excitation laser and the lasing mode characteristic of a single ZnO nanowire.