Plasmon-coupled graphene nanoantenna arrays for high-responsivity and tunable terahertz photodetection

Efficient room–temperature terahertz (THz) photodetection remains a critical prerequisite for emerging applications in imaging, spectroscopy, and wireless communication. In this work, we present a plasmon–coupled graphene photodetector that integrates a periodic array of gold nanoantennas to achieve broadband and gate–tunable THz response. The device architecture was investigated using self–consistent finite–difference time–domain (FDTD) and finite–element (FEM) simulations, revealing a local electric–field enhancement of approximately 40 × at the graphene–antenna interface. This strong plasmonic coupling leads to high theoretical performance metrics, including a peak voltage responsivity of 175 V W⁻ 1 at 2 THz, a noise–equivalent power below 2 pW/√Hz , and wideband operation across 0.5–5 THz. The spectral response can be dynamically tuned by electrostatic control of the graphene Fermi level (0.1–0.4 eV) under moderate gate bias, enabling adaptive detection and multispectral functionality. These findings demonstrate a scalable and practical pathway toward the development of room-temperature, tunable terahertz photodetectors based on plasmonically coupled graphene nanoantenna arrays. The proposed architecture offers significant promise for next-generation sensing and communication systems, with performance metrics that position it as a compelling candidate for versatile THz device platforms.