Recent advances in the physics of Dirac plasmons in graphene and related 2D materials and their THz device applications

Abstract The terahertz (THz) frequency range (0.1–10 THz) bridges the electronic and photonic spectral domains and offers key opportunities for high-speed communication, sensing, and spectroscopy. However, the realization of compact, coherent, and room-temperature THz sources and detectors remains still a long-standing challenge. Recent advances in two-dimensional (2D) materials, hosting graphene-like massless Dirac fermions, have opened some new paths toward overcoming this limitation. This paper reviews recent advances in the physics of Dirac plasmons in graphene and related 2D heterostructure materials and their THz device applications. It first outlines the fundamentals of 2D plasmon hydrodynamics, nonlinearities, and current-driven instabilities, including Dyakonov–Shur Ryzhii–Satou–Shur, and Cherenkov-type mechanisms. A new mechanism, Coulomb drag instability, recently discovered by the authors, is theoretically shown to provide the largest plasmonic gain among these mechanisms, offering a new route to efficient THz amplification and lasing. Its experimental verification is currently in progress. The review also discusses graphene-based plasmonic lasers, amplifiers, and detectors, and recent developments in graphene/black-arsenic–phosphorus heterostructures that enable band-structure and plasmonic engineering. Finally, topological-insulator-based heterostructures are introduced as promising material systems. These advances demonstrate that Dirac plasmon physics provides a robust foundation for next-generation THz device technology.