Department of Physics, Korea University, Seoul, Korea.
Sci Rep. 2013;3:2423. doi: 10.1038/srep02423.
Metals can transmit light by tunnelling when they possess skin-depth thickness. Tunnelling can be resonantly enhanced if resonators are added to each side of a metal film, such as additional dielectric layers or periodic structures on a metal surface. Here we show that, even with no additional resonators, tunnelling resonance can arise if the metal film is confined and fractionally thin. In a slit waveguide filled with a negative permittivity metallic slab of thickness L, resonance is shown to arise at fractional thicknesses (L = Const./m; m = 1,2,3,…) by the excitation of 'vortex plasmons'. We experimentally demonstrate fractional tunnelling resonance and vortex plasmons using microwave and negative permittivity metamaterials. The measured spectral peaks of the fractional tunnelling resonance and modes of the vortex plasmons agree with theoretical predictions. Fractional tunnelling resonance and vortex plasmons open new perspectives in resonance physics and promise potential applications in nanotechnology.
当金属具有趋肤深度厚度时，它们可以通过隧道传输光。如果在金属膜的每一侧添加谐振器，例如在金属表面添加额外的介电层或周期性结构，隧道谐振可以得到共振增强。在这里，我们表明，即使没有额外的谐振器，如果金属膜受到限制且呈分数薄，则也可能会出现隧道谐振。在充满厚度为 L 的负介电常数金属板的狭缝波导中，通过激发“涡旋等离子体”，在分数厚度（L = Const./m; m = 1,2,3，...）处显示出共振。我们使用微波和负介电常数超材料实验证明了分数隧道共振和涡旋等离子体。分数隧道共振的测量光谱峰值和涡旋等离子体的模式与理论预测相符。分数隧道共振和涡旋等离子体为共振物理学开辟了新的视角，并有望在纳米技术中得到应用。
