摘要
采用三维时间域有限差分 (FDTD)方法研究了扫描近场光学显微镜中光纤微探针的近场分布特性。研究结果表明 ,锥形裸光纤探针的近场光中 ,以从探针锥变区侧面泄露的光即传播场为主 ,当在探针的侧面镀上一层金属膜对于从侧面泄露的光具有较好屏蔽效果 ,因而比裸光纤探针具有更好的空间束缚能力 ;无论是裸光纤探针还是金属膜探针 ,入射偏振光从针尖出射后发生了退极化现象 ,近场分布中产生与入射光偏振方向垂直的其它两个电场分量 ,而且金属膜探针的退极化分量对近场分布的影响比裸探针显著得多。如果在近场成像中接收退极化分量而不是总场则可以提高近场成像的对比度。
The near-field distribution of uncoated and metal-coated fiber-optic probes were characterized by the method of three-dimensional finite-difference time-domain (FDTD). The result reveals that, for an uncoated probe, propagating wave emitting from the conic side dominates the near-field distribution, and when a film of metal is coated, the coated probe can confine the wave more strictly inside it. The polarized incident wave becomes depolarized after emitting from the small aperture of two kinds of probes. There are two electric-field components whose polarization direction is perpendicular to that of the incident one. The image contrast can be improved if the polarized components instead of the total field are detected. The relationship between the distribution characteristics of near-field distribution and the phenomenon of depolarization was described.
出处
《光学学报》
EI
CAS
CSCD
北大核心
2001年第10期1234-1238,共5页
Acta Optica Sinica
关键词
近场光学
时域有限差分
倏逝波
光纤微探针
显微镜
近场分布
Finite difference method
Light propagation
Optical fibers
Polarization
Time domain analysis
