金属-石墨烯光子晶体-金属结构的吸收特性

金属-石墨烯光子晶体-金属复合结构可实现多带吸收。为了解该复合结构的吸收特性,采用传输矩阵法,研究了可见光波段结构参量对其多带吸收特性的影响。结果表明,各吸收带的中心波长与石墨烯化学势的大小无关;吸收带的个数与石墨烯光子晶体周期单元个数及电介质层的光学厚度有关;周期单元数越大,介质层光学厚度越大,吸收带的个数就越多;两金属层的厚度对吸收特性的影响存在差异,要使光吸收率尽可能高,衬底一侧的金属层要尽可能厚,入射空间一侧的金属层的厚度则存在一个最优值;垂直入射时合理选择相关参量,各主要吸收峰可有90%以上的吸收率。此研究结果为研制基于石墨烯的多带光吸收器提供了参考。

Absorption characteristics of metal-graphene photonic crystal-metal structures

Metal-graphene photonic crystal-metal composite structures can achieve multi-band absorption. In order to understand the absorption characteristics of the composite structure, the influence of visible band structure parameters on multi-band absorption characteristics was studied with transfer matrix method. The results show that, central wavelength of each absorption band is independent of the chemical potential of graphene. The number of absorption bands is related to the number of periodic units of graphene photonic crystals and the optical thickness of dielectric layer. The larger the number of periodic elements, the greater the optical thickness of the dielectric layer, the more the number of absorption bands. The influence of the thickness of the two metal layers on the absorption characteristics is different. In order to make the optical absorption as high as possible, the metal layer on the side of the substrate should be as thick as possible. The thickness of the metal layer on the side of the incident space has an optimal value. When the parameters are selected reasonably at normal incidence, the absorption rate of each main absorption peak can be more than 90%. The results provide a reference for the development of multi-band optical absorbers based on graphene.