Thermally excited near-field radiation and far-field interference.
Thermally excited near-field radiation and far-field interference.
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DOI：
10.1364/oe.19.007695
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发表时间：
2011-04
期刊：
影响因子：
3.8
通讯作者：
Y. Kajihara;K. Kosaka;S. Komiyama
中科院分区：
文献类型：
--
作者：
Y. Kajihara;K. Kosaka;S. Komiyama
利用散射型扫描近场光学显微镜（波长：~14.5 μm）研究了300 K下GaAs、SiO(2)和SiC上Au层的热辐射。获得了空间分辨率为~60 nm的清晰近场图像。不同解调方式的近场信号随探头高度h的增加而迅速衰减，特征衰减长度为40 ~60 nm。近场图像不受任何面内空间干扰的影响。这些发现可以用理论上预期的表面倏逝波来解释，表面倏逝波在材料表面附近被热激发。在近场区（1 μm < h）外，信号重新出现，并以h的正弦函数变化，表现出类似驻波的干涉图样。这些远场信号归因于弱环境辐射的影响。
Thermal radiation from samples of Au layers patterned on GaAs, SiO(2), and SiC at 300 K are studied with a scattering-type scanning near-field optical microscope (wavelength: ~14.5 μm), without applying external illumination. Clear near-field images are obtained with a spatial resolution of ~60 nm. All the near field signals derived from different demodulation procedures decrease rapidly with increasing probe height h with characteristic decay lengths of 40 ~60 nm. Near-field images are free from any signature of in-plane spatial interference. The findings are accounted for by theoretically expected surface evanescent waves, which are thermally excited in the close vicinity of material surfaces. Outside the near-field zone (1 μm < h), signals reappear and vary as a sinusoidal function of h, exhibiting a standing wave-like interference pattern. These far-field signals are ascribed to the effect of weak ambient radiation.