Generation of a photonic nanojet with a slightly subwavelength waist at the back side of a dielectric microsphere or microcylinder impinged by a plane wave has recently shown that the near-field effects may hold not only inside the dielectric microparticle, but also outside it. In this paper we explain how to drastically increase the external near-field effect. For it one has to replace a plane wave or a Gaussian beam by the fully symmetric diffraction-free beam. In this case we observe a deeply subwavelength focusing of the incident beam near the rear edge of the microcylinder. This effect is accompanied by a very strong enhancement of the local electric intensity. Microcylinders with slightly different parameters grant the significant enhancement of the intensity on the whole cylinder surface. These implications of the resonant scattering result from the destructive interference of the propagating spatial harmonics which vanish at the back side of the cylinder in favor of the evanescent ones.

最近，在平面波撞击的介电微球体或微圆柱体的背面具有略微亚波长腰部的光子纳米射流的产生表明，近场效应不仅可以在介电微粒内部保持，而且可以在介电微粒外部保持。在本文中，我们解释了如何大幅增加外部近场效应。为此，必须用完全对称的无衍射光束代替平面波或高斯光束。在这种情况下，我们观察到入射光束在微圆柱体后边缘附近的深亚波长聚焦。这种效应伴随着局部电强度的非常强烈的增强。参数略有不同的微型气缸可显着提高整个气缸表面的强度。