Spot-size reduction in terahertz apertureless near-field imaging.
Spot-size reduction in terahertz apertureless near-field imaging.
复制标题
太赫兹无孔径近场成像中光斑尺寸的减小。
DOI：
10.1364/ol.29.002306
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发表时间：
2004
期刊：
影响因子：
3.6
通讯作者：
N. V. D. van der Valk
中科院分区：
文献类型：
--
作者：
P. Planken;N. V. D. van der Valk
我们展示了金属尖端的太赫兹（THz）近场的测量和计算，其特殊形状的半圆形尖端使我们能够识别尖端尖端和轴对测量信号的单独贡献。我们发现，当尖端晶体距离不被调制时，测量到的近场信号被尖端轴的贡献所淹没，导致相对较大的太赫兹光斑尺寸。当调制尖端晶体距离时，在调制频率下进行锁相检测，只观察到半圆顶点的近场分布，从而大大减小太赫兹光斑尺寸，从而提高了空间分辨率。
We show measurements and calculations of the terahertz (THz) near field of a metal tip with a specially formed, semicircular apex that allows us to identify the separate contributions of the tip apex and shaft to the measured signal. We find that when the tip-crystal distance is not modulated the measured near-field signal is overwhelmed by contributions from the tip shaft, resulting in a relatively large THz spot size. When the tip-crystal distance is modulated, with subsequent lock-in detection at the modulation frequency, only the near-field distribution of the semicircular apex is observed, resulting in a much smaller THz spot size and thus improved spatial resolution.