Graphene plasmons provide a compelling avenue toward chip-scale dynamic tuning of infrared light. Dynamic tunability emerges through controlled alterations in the optical properties of the system defining graphene’s plasmonic dispersion. Typically, electrostatic induced alterations of the carrier concentration in graphene working in conjunction with mobility have been considered the primary factors dictating plasmonic tunability. We find here that the surrounding dielectric environment also plays a primary role, dictating not just the energy of the graphene plasmon but so too the magnitude of its tuning and spectral width. To arrive at this conclusion, poles in the imaginary component of the reflection coefficient are used to efficiently survey the effect of the surrounding dielectric on the tuning of the graphene plasmon. By investigating several common polar materials, optical phonons (i.e., the Reststrahlen band) of the dielectric substrate are shown to appreciably affect not only the plasmon’s spectral location but its tunability, and its resonance shape as well. In particular, tunability is maximized when the resonances are spectrally distant from the Reststrahlen band, whereas sharp resonances (i.e., high-$Q$) are achievable at the band’s edge. These observations both underscore the necessity of viewing the dielectric environment in aggregate when considering the plasmonic response derived from two-dimensional materials and provide heuristics to design dynamically tunable graphene-based infrared devices.

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通过介电环境提高石墨烯等离子设备的性能

石墨烯等离子体激元为芯片级动态红外调谐提供了引人注目的途径。动态可调谐性是通过控制定义石墨烯等离激元色散的系统光学特性的变化而出现的。通常，石墨烯中静电引起的载流子浓度的改变与迁移率的结合已被认为是决定等离子体可调谐性的主要因素。我们在这里发现周围的介电环境也起着主要作用，不仅决定了石墨烯等离子体激元的能量，而且决定了其调谐幅度和光谱宽度。为了得出这个结论，反射系数的虚部中的极点被用来有效地测量周围电介质对石墨烯等离子体激元调谐的影响。通过研究几种常见的极性材料，电介质基板的光子（即Reststrahlen带）被显示出不仅会影响等离激元的光谱位置，而且会影响其可调谐性以及共振形状。特别是，当共振在光谱上远离Reststrahlen谱带时，可调谐性将最大化，而尖锐的共振（即高$问$）可以在乐队的边缘实现。这些观察结果都强调了在考虑源自二维材料的等离子体响应时，必须从总体上观察介电环境，并提供启发式方法来设计基于动态可调谐石墨烯的红外设备。