Nonlocal Time-Resolved Terahertz Spectroscopy in the Near Field
Nonlocal Time-Resolved Terahertz Spectroscopy in the Near Field
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DOI：
10.1021/acsphotonics.1c01367
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发表时间：
2021-10-01
期刊：
影响因子：
7
通讯作者：
Mittleman, Daniel M.
中科院分区：
文献类型：
--
作者：
Pizzuto, Angela;Castro-Camus, Enrique;Mittleman, Daniel M.
散射型近场光学显微镜（s-SNOM）使亚波长光谱测量各种各样的材料和在一个大的光谱范围。这些基于尖端的测量在长波长范围内特别令人感兴趣，其中单个纳米级样品的研究非常具有挑战性。s-SNOM技术与短脉冲持续时间的结合开辟了一个新的可能性领域，其中纳米系统可以通过高空间和时间分辨率来表征，例如通过光泵，太赫兹探针测量。在这里，我们展示了第一个“非本地”的泵浦探测测量使用散射型扫描近场显微镜技术，其中的泵浦点从探测位置横向位移。我们观察到非本地效应对应于这个泵浦探测偏移，与载流子漂移到s-SNOM近场探测区。
Scattering-type near-field optical microscopy (s-SNOM) has enabled subwavelength spectroscopy measurements on a wide variety of materials and over a large spectral range. These tip-based measurements are of particular interest in the long wavelength regimes, where the study of individual nanoscale samples is very challenging. The combination of s-SNOM techniques with short pulse durations has opened a new realm of possibilities in which nanosystems can be characterized with both high spatial and temporal resolution, for example via optical-pump, terahertz-probe measurements. Here, we demonstrate the first "nonlocal" pump-probe measurement using a scattering-type scanning near-field microscopy technique, in which the pump spot is laterally displaced from the probe location. We observe nonlocal effects corresponding to this pump-probe offset, associated with carrier drift into the s-SNOM near-field probe region.