Graphene and GaN-based 2D Plasmonic Nanostructures for THz Filters, Detectors, and Amplifiers

When two-dimensional (2D) electron or hole systems are scaled to nanometer dimensions, their resonant plasma frequencies can extend into the terahertz (THz) range. In such nanostructures, the addition of metallic gates enables control over the 2D carrier density, facilitating voltage-tunable resonant plasma frequencies. This capability makes gated 2D nanostructures highly promising for the development of innovative, voltage-controlled THz devices. This work provides an overview of recent experimental and theoretical advancements in 2D plasmonic nanostructures, highlighting their potential applications as electrically tunable THz filters, detectors, and amplifiers. We specifically examine graphene and AlGaN/GaN-based grating-gate systems, demonstrating that, despite their distinct energy band structures, both materials can serve as efficient and versatile platforms for voltage-tunable THz optoelectronic devices.