Fano resonant behaviour of waveguide mode in all-dielectric multilayer structure directly monitored by fluorescence of embedded dye molecules
Fano resonant behaviour of waveguide mode in all-dielectric multilayer structure directly monitored by fluorescence of embedded dye molecules
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DOI：
10.1088/2040-8986/ab42cf
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发表时间：
2019-09
影响因子：
2.1
通讯作者：
Byungjun Kang;Ken Motokura;M. Fujii;D. Nesterenko;Z. Sekkat;S. Hayashi
中科院分区：
文献类型：
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作者：
Byungjun Kang;Ken Motokura;M. Fujii;D. Nesterenko;Z. Sekkat;S. Hayashi
提出了一种直接监测多层结构中波导层内局部电场Fano共振行为的方法。制备了由聚乙烯醇间隔层分隔的两层聚苯乙烯波导组成的全介质多层结构。其中一个波导层掺杂有荧光染料分子。在Kretschmann衰减全反射几何结构中测量样品的荧光光谱作为激发光入射角的函数。角扫描荧光激发光谱表现出一个尖锐的法诺线形状叠加在一个宽带。多层结构内的电场分布的电磁计算的结果表明，染料掺杂的波导层内的局部电场表现出Fano谐振行为，由于近场耦合到由另一个波导层支持的波导模式。使用计算的局部电场，基于点偶极模型计算理论荧光光谱。发现理论荧光光谱非常好地再现了实验荧光光谱，证实了在荧光光谱中观察到的Fano线形是染料掺杂层内部局部电场的Fano共振行为的表现。
A method that allows direct monitoring of Fano resonant behaviours of local electric fields inside a waveguide layer in multilayer structures was developed. All-dielectric multilayer structures consisting of two polystyrene waveguide layers separated by a polyvinyl alcohol spacer layer were prepared. One of the waveguide layers was doped with fluorescent dye molecules. The fluorescence spectra of the sample were measured in a Kretschmann attenuated-total-reflection geometry as a function of the angle of incidence of the excitation light. The angle-scan fluorescence excitation spectra exhibited a sharp Fano line shape superposed on a broad band. Results of electromagnetic calculations of the electric field distribution inside the multilayer structure revealed that the local electric fields inside the dye-doped waveguide layer exhibit Fano resonant behaviours due to the near-field coupling to the waveguide mode supported by another waveguide layer. Using the calculated local electric fields, theoretical fluorescence spectra were calculated based on a point dipole model. The theoretical fluorescence spectra were found to reproduce the experimental ones very well, confirming that the observed Fano line shapes in the fluorescence spectra are the manifestation of the Fano resonant behaviours of the local electric fields inside the dye-doped layer.