Fano resonance in metallic grating via strongly coupled subwavelength resonators
Fano resonance in metallic grating via strongly coupled subwavelength resonators
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DOI：
10.1017/s0956792520000200
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发表时间：
2019-11
影响因子：
1.9
通讯作者：
Junshan Lin;Hai Zhang
中科院分区：
文献类型：
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作者：
Junshan Lin;Hai Zhang
我们研究了耦合谐振器在光栅结构中的Fano谐振。光栅由具有周期性排列的亚波长缝隙孔的完美导电板组成，在每个周期内，一对缝隙彼此非常接近。狭缝孔充当谐振器并且强耦合。它严格地表明，存在两组共振对应的极点的散射问题。一个共振序列具有ε量级的虚部，其中ε是狭缝孔径的大小，而另一个序列具有ε 2量级的虚部。当与共振频率的入射波耦合时，由后者引起的窄带共振散射将干扰由前者引起的更宽的背景共振辐射。这两种共振的干涉产生Fano型透射异常，只要狭缝孔径尺寸与入射波长相比较小，该透射异常就持续存在于光栅结构的整个辐射连续谱中。
We investigate the Fano resonance in grating structures using coupled resonators. The grating consists of a perfectly conducting slab with periodically arranged subwavelength slit holes, where inside each period, a pair of slits sit very close to each other. The slit holes act as resonators and are strongly coupled. It is shown rigorously that there exist two groups of resonances corresponding to poles of the scattering problem. One sequence of resonances has imaginary part in the order of ε, where ε is the size of the slit aperture, while the other sequence has imaginary part in the order of ε 2. When coupled with the incident wave at resonant frequencies, the narrow-band resonant scattering induced by the latter will interfere with the broader background resonant radiation induced by the former. The interference of these two resonances generates the Fano-type transmission anomaly, which persists in the whole radiation continuum of the grating structure as long as the slit aperture size is small compared to the incident wavelength.