Band structures of armchair graphene nanoribbons (AGNRs) under crossed external fields are calculated within the tight-binding model. Magnetic field reduces energy-gap and flattens energy dispersions of band-edge states. Electric field strongly distorts energy dispersions leading to a reduction of energy-gap, a shift in band-edge states and many local maxima and minima. The complex dielectric function is further calculated in long-wavelength limit in which many peak-dip structures reveal characteristics of transparency and absorption. Furthermore, plasmon spectra are determined by frequency-position, sharpness, and number of peak-dip structures those are related to field strength and ribbon’s geometry. The field-induced extra transition channels could make a change in the frequency, peak-height, and number of branch of plasmons that can make AGNRs into a tunable terahertz nano-material. The photoninduced plasmons are further reflected in the edge-structures of reflectance spectra, unveiling the transition between transparency and absorption. Reflectance spectra strongly depend on external fields and ribbon’s geometry that will be verified by experimental measurements.

在紧密结合模型中计算了交叉的外部场下扶手椅石墨烯纳米带（AGNR）的能带结构。磁场减小了能隙，并使频带边缘态的能量分散平坦。电场会严重扭曲能量散布，从而导致能隙减小，能带边缘状态转移以及许多局部最大值和最小值。复介电函数是在长波长范围内进一步计算的，在该波长范围内，许多峰垂结构显示出透明性和吸收性。此外，等离激元光谱由频率位置，清晰度和与电场强度和碳带几何形状有关的峰浸结构的数量确定。场感应的额外跃迁通道可能会改变频率，峰高，可以使AGNR成为可调太赫兹纳米材料的等离激元的分支数目。光子诱发的等离激元在反射光谱的边缘结构中进一步反射，揭示了透明性和吸收性之间的过渡。反射光谱在很大程度上取决于外部场和色带的几何形状，这些将通过实验测量来验证。