Liu Zhengqi, Liu Guiqiang, Liu Xiaoshan, Huang Shan, Wang Yan, Pan Pingping, Liu Mulin
Provincial Key Laboratory of Nanomaterials and Sensors, Institute of Optoelectronic Materials and Technology, College of Physics and Communication Electronics, Provincial Key Laboratory of Optoelectronic and Telecommunication, Jiangxi Normal University, Nanchang 330022, People's Republic of China.
Nanotechnology. 2015 Jun 12;26(23):235702. doi: 10.1088/0957-4484/26/23/235702. Epub 2015 May 19.
Resonant plasmonic and metamaterial absorbers are of particular interest for applications in a wide variety of nanotechnologies including thermophotovoltaics, photothermal therapy, hot-electron collection and biosensing. However, it is rather challenging to realize ultra-narrow absorbers using plasmonic materials due to large optical losses in metals that inevitably decrease the quality of optical resonators. Here, we theoretically report methods to achieve an ultra-narrow light absorption meta-surface by using photonic modes of the optical cavities, which strongly couple with the plasmon resonances of the metallic nanostructures. Multispectral light absorption with absorption amplitude exceeding 99% and a bandwidth approaching 10 nm is achieved at the optical frequencies. Moreover, by introducing a thick dielectric coupling cavity, the number of absorption bands can be strongly increased and the bandwidth can even be narrowed to less than 5 nm due to the resonant spectrum splitting enabled by strong coupling between the plasmon resonances and the optical cavity modes. Designing such optical cavity-coupled meta-surface structures is a promising route for achieving ultra-narrow multiband absorbers, which can be used in absorption filters, narrow-band multispectral thermal emitters and thermophotovoltaics.
共振等离子体和超材料吸收器在包括热光伏、光热疗法、热电子收集和生物传感在内的各种纳米技术应用中特别受关注。然而，由于金属中的大量光学损耗不可避免地降低了光学谐振器的质量，使用等离子体材料实现超窄吸收器颇具挑战性。在此，我们从理论上报告了通过利用光学腔的光子模式来实现超窄光吸收超表面的方法，这些光子模式与金属纳米结构的等离子体共振强烈耦合。在光频下实现了吸收幅度超过99%且带宽接近10 nm的多光谱光吸收。此外，通过引入厚介电耦合腔，由于等离子体共振与光学腔模式之间的强耦合实现的共振光谱分裂，吸收带的数量可以显著增加，带宽甚至可以窄至小于5 nm。设计这种光学腔耦合超表面结构是实现超窄多波段吸收器的一条有前途的途径，可用于吸收滤波器、窄带多光谱热发射器和热光伏。
