石墨烯红外等离极化激元的光泵浦调制研究

In the infrared regime, graphene are proposed as an advanced plasmonic material because of the advantages of graphene plasmons (GPs). Recently, the combination of graphene and conventional subwavelength metallic structures has sparked a wealth of experimental and theoretical works due to the improved tunability and photon confinement. In this project, we propose new-style graphene/dielectric/metal plasmonic systems in which a new class of coupled graphene plasmon polaritons (CGPPs) can be realized via fundamental coupling of conventional GPs and confined photon modes. By tuning the temperature and optical pumping, the infrared properties of CGPPs will be theoretically and experimentally studied. Through an improved multiple reflection model (IMRM) established in this project, we will investigate the physical mechanism of the temperature and optical pumping tuning of CGPPs. The main content of this project is listed as follows: (1) In the wavelength range of 1~14 μm, the effects of the temperature and optical pumping on the optical conductance of monolayer graphene will be investigated. (2) Based on the infrared responses of the graphene/dielectric/metal plasmonic systems and the IMRM, we will reveal the mechanism of the coupling between GPs and confined photon modes. (3) By tuning the temperature and/or the power of pump laser, the changes in the infrared properties of CGPPs and the corresponding principle will be studied, especially in the near-infrared regime. The results of this project will give an insight into the physical origin of CGPPs supported by the plasmonic systems proposed here. Meanwhile, the temperature and optical pumping tunability of CGPPs can be applied to new-type infrared plasmonic devices.

在红外波段，石墨烯等离激元的优异特性令石墨烯成为了一种新型等离材料。近年来，人们将石墨烯与传统亚波长金属结构相结合获得了更好的可调谐特性及光子束缚能力。本项目提出了两种新型石墨烯/介质/金属等离系统，系统中的传统石墨烯等离激元将与束缚光子模式相互作用，形成一种新的耦合型石墨烯等离极化激元(缩写CGPP)。通过调谐温度和泵浦光功率，本项目将从实验和理论两方面对CGPP的红外特性变化进行研究。主要创新内容如下：(1)在1~14 μm波段，研究温度和光泵浦对单层石墨烯光电导的影响及其机理；(2)基于石墨烯/介质/金属等离系统的红外响应实验及改进的多重反射模型，项目将揭示系统中石墨烯等离激元与束缚光子模式耦合形成CGPP的物理机制；(3)项目还将研究改变温度和泵浦激光功率会对CGPP红外（特别是近红外）特性造成的影响及其原理。取得的成果将有助于深入理解CGPP的物理本质，并应用于新型红外等离器件。

在长波段，石墨烯等离激元的优异特性令石墨烯成为了一种新型等离材料。近年来，人们将石墨烯与传统亚波长金属结构相结合获得了更好的可调谐特性及光子束缚能力。本项目基于红外和太赫兹（THz）光谱测量，研究了几类石墨烯等离系统的光电特性及其光泵浦调控，主要研究内容和重要结果如下：(1)研究了连续光泵浦下单层石墨烯/介质（衬底）系统的红外及THz特性，证明了该系统的光控等离特性及光控布儒斯特效应；(2)研究了几种石墨烯/微纳结构系统的等离特性及其光调制过程，论证了相关物理机制；(3)基于前述实验系统或理论模型，拓展研究了超导薄膜、二维半导体及超构材料等的光电特性及其温度、泵浦光依赖特性。取得的成果将有助于深入理解各种二维材料相关系统中的等离极化激元，并应用于新型红外等离器件。