倏逝波及其能流密度研究

全反射的倏逝波具有特殊的性质和重要的应用。针对现有能量流动特点研究都略显简单或缺乏系统性的问题,应用电磁场理论,推导了线偏振光全反射时倏逝波的电场强度、磁场强度、能流密度和平均能流密度数学表达式;通过数值计算,分析了倏逝波平均能流密度大小及方向与入射角、入射光矢量方向之间的关系。得出以下主要结论:一般情况下,倏逝波的能量流动不仅被限制在介质分界面处的一个薄层内,平均能流密度的大小与入射角有关,而且平均能流密度的方向与入射面有一定夹角;只有当入射光矢量平行或垂直于入射面时,倏逝波的平均能流密度方向才平行于入射面。

Research on Evanescent Wave and Its Energy Flux Density

Evanescent wave in total internal reflection has special characteristics and important applications. It is very necessary to research on the characteristics of the energy flow of evanescent wave. But the existing studies are simple or incomplete. In this paper, based on the theory of electromagnetic field, the mathematical expressions of electric field intensity, magnetic field intensity, energy flux density and average energy flux density(AEFD) of the evanescent wave are derived, as the incident light is linearly polarized. By numerical computation, the links between the modulus and direction of AEFD of evanescent wave to the incident angle and incident light vector direction, are analyzed. The conclusions include that the energy flow of evanescent wave is limited within a thin layer near the interface of media, the modulus of AEFD is influenced by incident angle, and there is an angle between the direction of AEFD and incident plane, as well; only as the incident light vector is parallel with or perpendicular to the incident plane, the direction of AEFD of evanescent wave is in the incident plane. These mathematical expressions of these physical quantities and conclusions are helpful for understanding the evanescent wave and doing the related studies.