周期地嵌入电介质球壳的金属表层的表面等离子激元及其与电介质腔体模式的耦合

通过观察金属底板中周期地嵌入电介质球壳的体系的光学吸收性质，研究了表面等离子激元 以及与其他电磁模式的耦合特性.在这种周期结构的金属表面，发现存在两种响应频率，分 别对应于表面等离子激元模式和金属中的电介质腔体模式.在这些响应频率上，可观察到与 它们相对应的吸收峰.由于金属的表面模式不能与平面入射光直接耦合，而腔体模式与平面 入射光和表面等离子激元模式的耦合一般较弱，因而通常情况下这些吸收峰的峰值有限.然 而，通过调整体系中的某些参数，可以使腔体模式和表面模式的频率非常接近，这时二者之 间的耦合强度将大大提高.此时，在相应的频率附近可观察到极强的吸收峰.详细地研究了介 质球壳的物理和几何参数对此共振吸收的影响. 关键词： 腔体模式 表面等离子体模式 共振吸收

Surface plasmon polaritons and its coupling with cavity mode in the system of dielectric spherical shells periodically mounted in a metal substrate

We investigate the surface plasmon polaritons and its coupling with other electromagnetic modes by observing the absorption spectrum on a system of dielectric spherical shells periodically mounted in a metal substrate. We found that there exist two resonance frequencies in the system corresponding to surface plasmon polaritons mode and cavity mode. At these frequencies, we can find related peaks i n absorbance. Since the surface plasmon polaritons cannot couple with the incide nt plane wave directly and both couplings of the cavity mode with the incident w ave and the surface plasmon polaritons are also weak, so the strength of absorpt ion peaks are generally very limited. However, we can adjust some parameters in the system to make the surface plasmon polaritons and the cavity mode with almos t the same frequency. In this case, the coupling can be dramatically enhanced, a nd we can observe very strong peaks in absorbance. The relationships of resonanc e absorption with some physical and geometrical parameters are discussed in deta il.