Journal of the Optical Society of America. A, Optics, image science, and vision | 2021
Modified rigorous coupled-wave analysis for grating-based plasmonic structures with a delta-thin conductive channel: far- and near-field study.
Abstract
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.