Kuznetsova T I, Lebedev V S
P.N. Lebedev Physical Institute, Leninsky prospect 53, Moscow 119991, Russia.
Phys Rev E Stat Nonlin Soft Matter Phys. 2008 Jul;78(1 Pt 2):016607. doi: 10.1103/PhysRevE.78.016607. Epub 2008 Jul 31.
The results of the theoretical studies on the leakage of the optical radiation through a truncated waveguide with a subwavelength-sized exit hole are reported. We develop a self-consistent approach for the description of the fields behavior by taking into account the transformation of the initial wave into all possible modes, which appear due to the influence of the exit aperture. Our approach allows us to evaluate the amplitude reflection coefficient for the initial evanescent wave and to establish its relationship with the impedance of an infinite waveguide and the impedance of the exit aperture coupling a truncated waveguide with a free space. We determine the complex flow through the exit hole and the transmission coefficient to the far-field zone and express them through the reflection coefficient. Special attention in the work is paid to the evaluation of specific dependencies of the reflection and transmission coefficients on the ratio of the aperture radius to the light wavelength, on the dielectric constants of the waveguide core and the surrounding matter, and on the type of the waveguide mode. It is demonstrated that in the case of a metallic matter at the exit of a waveguide there is a strong resonance enhancement in the amplitude of the reflected wave and in the resulting amplitude of the tangential component of the electric field.
报道了关于光辐射通过具有亚波长尺寸出射孔的截断波导泄漏的理论研究结果。我们通过考虑初始波向所有可能模式的转换来开发一种自洽方法，这些模式是由于出射孔径的影响而出现的。我们的方法使我们能够评估初始倏逝波的振幅反射系数，并确定其与无限波导的阻抗以及将截断波导与自由空间耦合的出射孔径的阻抗之间的关系。我们确定通过出射孔的复通量以及到远场区域的传输系数，并通过反射系数来表示它们。该工作特别关注评估反射系数和传输系数对孔径半径与光波长之比、波导芯和周围物质的介电常数以及波导模式类型的特定依赖性。结果表明，在波导出射端为金属物质的情况下，反射波的振幅以及由此产生的电场切向分量的振幅会有强烈的共振增强。
