A quantitative theory describing optical tunneling effects related to near-field diffraction of light from a small hole in a flat screen is established. We show that in the absence of local-field corrections, optical tunneling (i.e., the possibility of detecting photons in front of the “light cone”) in near-field diffraction appears solely via the longitudinal Green tensor, GL, and the space-like part of the retarded transverse propagator, GTspace. It is demonstrated that GTspace in the space-time domain can be written as a product of an electrostatic point-dipole tensor and a time factor, which obeys microcausality and is nonvanishing only in front of a plane “light cone.” Special attention is devoted to an analysis of the tunneling of an electromagnetic pulse of finite duration through a small hole in a thin screen. In this particular case, the tunneling signal in the point of observation arises from a somewhat complicated interplay between the time interval in which the effective aperture current density is nonvanishing and the time it takes for the elementary trailing edges of the individual space-like wavelets to pass the observation point. To achieve a self-consistent description of the tunneling process, we propose to use a certain spatially nonlocal and linear constitutive equation. In this equation, which is an improved version of those used up to now in diffraction theory, only the transverse part of the electric field occurs because the induced longitudinal field is not a dynamical variable in electrodynamics. Finally, we suggest to measure the optical tunneling related to small hole diffraction via a modified frustrated total internal reflection tunneling experiment, and we indicate how it might be possible to extend the present theory to single-photon diffraction tunneling.

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关于来自小孔的光的近场衍射中的光学隧道效应

建立了描述与来自平面屏幕中的小孔的光的近场衍射相关的光学隧道效应的定量理论。我们表明，在没有局部场校正的情况下，近场衍射中的光学隧道效应（即在“光锥”前面检测光子的可能性）仅通过纵向格林张量 GL 和空间-像延迟横向传播器的一部分，GTspace。证明了时空域中的GT空间可以写成静电点偶极子张量和时间因子的乘积，它遵循微因果关系，并且仅在平面“光锥”之前不消失。特别注意分析有限持续时间的电磁脉冲穿过薄屏幕上的小孔的隧道效应。在这种特殊情况下，观察点的隧穿信号源于有效孔径电流密度不为零的时间间隔与单个类空间小波的基本后沿通过观察点所需的时间之间的某种复杂的相互作用。为了实现隧道过程的自洽描述，我们建议使用一定的空间非局部和线性本构方程。在这个方程中，它是迄今为止在衍射理论中使用的那些方程的改进版本，只出现电场的横向部分，因为感应的纵向场不是电动力学中的动态变量。最后，我们建议通过改进的受抑全内反射隧穿实验测量与小孔衍射相关的光学隧穿，