The modified rigorous coupled-wave analysis technique is developed to describe the optical characteristics of the plasmonic structures with the grating-gated delta-thin conductive channel in the far- and near-field zones of electromagnetic waves. The technique was applied for analysis of the resonant properties of AlGaN/GaN heterostructures combined with a deeply subwavelength metallic grating, which facilitates the excitation of the two-dimensional plasmons in the terahertz (THz) frequency range. The convergence of the calculations at the frequencies near the plasmon resonances is discussed. The impact of the grating’s parameters, including filling factor and thickness of the grating, on resonant absorption of the structure was investigated in detail. The spatial distributions of the electromagnetic field in a near-field zone were used for the evaluation of total absorption of the plasmonic structures separating contributions of the grating-gated two-dimensional electron gas and the grating coupler.

中文翻译：

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修正的严格耦合波分析，用于具有薄导电通道的基于光栅的等离激元结构：远场和近场研究

开发了改进的严格耦合波分析技术，以描述在电磁波的远场和近场区域中具有光栅门控的δ薄导电通道的等离激元结构的光学特性。该技术被用于分析与深亚波长金属光栅结合的AlGaN / GaN异质结构的共振特性，这有助于激发太赫兹（THz）频率范围内的二维等离子体激元。讨论了在等离激元共振附近的频率处计算的收敛性。详细研究了光栅参数（包括填充系数和光栅厚度）对结构共振吸收的影响。