科研之友
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摘要
Self-collimation of tightly localized laser beams demonstrated in periodic media relies on a perfect-matched rephasing of the Fourier constituents of the wavefield induced by a plane isofrequency curve. An alternate way paved for the achievement of such a phase matching condition developed a suitable spatial filtering in order to select those frequencies experiencing the same phase velocity projected over a given orientation. In principle this procedure is valid for complex structured metamaterials. However, a great majority of studies have focused on free-space propagation leading to the well-known Bessel beams. This paper is devoted to the analysis of this sort of nondiffracting beams traveling in one-dimensional metallic-dielectric photonic crystals. Specifically we present a family of localized radiation modes in multilayered periodic media, where in-phase superposition of p-polarized waves leads to radiative confinement around the beam axis. Excitation of surface plasmon polaritons yields an enhanced localization normally to the interfaces. Subwavelength beam widths along an infinitely long distance might potentially be obtained.
- 出版日期2010-7
