采用时域有限差分方法对镀金属膜光纤探针在近场光探测中对光场产生的扰动和相互作用过程进行了数值分析。选择纳米孔径的隐失场光场和镀金属膜光纤探针建立了近场光探测的理论模型,讨论了探针孔径尺寸、扫描高度等因素对光场探测的影响,以及测量光场与初始光场之间的关系等。研究结果表明,当探针孔径尺寸与待测纳米孔径尺寸相当,探针扫描高度在接近探针孔径尺寸的一半时,测量得到的光场分布数据能够准确描述初始光场分布。

The interaction and the perturbation between a metal-coated fiber probe and an aperture evanescent field is analyzed numerically using finite-difference time-domain (FDTD) method. The simulation model consists of a sub-wavelength aperture and a metal-coated fiber probe scanning in constant height mode. Influences of the scanning height and the aperture size of the fiber probe on optical field detection are discussed. Relationship between the measured optical field and the initial optical field without perturbation is compared and analyzed. The research results reveal that when the aperture size of the probe is comparable with the measured nano-structure and the scanning height is close to half of the aperture size, the measured field distribution shows better similarity with the initial one, that is to say, it can describe the initial one accurately.