Multi-Band High-Performance Graphene Mid-Infrared Photodetector Based on Plasmonic and Fabry–Perot Resonances

Optical photodetectors are critical components in modern optical communication systems and advanced optoelectronic technologies, where enhancing their efficiency, sensitivity, and response speed remains a central research objective. In recent years, graphene has emerged as a highly promising candidate for next-generation photodetectors, owing to its exceptional carrier dynamics, broadband optical absorption, and tunable electrostatic properties. In this study, we present the design and modeling of a monolayer graphene-based mid-infrared photodetector that incorporates metallic nanoantennas to enhance optical absorption and device performance. The principal innovation of this study lies in the simultaneous utilization of plasmonic effects from the nanoantennas and Fabry–Perot resonances to amplify the local electric field and confine light within the structure, leading to a substantial increase in graphene’s light absorption. Numerical simulations based on FDTD and FEM methods demonstrate that this approach can boost the absorption rate up to 70%, resulting in a responsivity as high as 30 mA/W at a wavelength of 6.7 µm. Furthermore, by modifying structural parameters or tuning the gate voltage, the detection wavelength can be tuned within the 6–8 µm range, enabling versatile multi-band operation. In addition to optical and electrical analyses, this study rigorously models and simulates the fundamental noise mechanisms—including thermal, shot, and flicker noise—in the photodetector structure to realistically assess performance limitations and the signal-to-noise ratio. Detailed modeling of the graphene/metal contact resistance and noise characteristics provides a deeper understanding of the constraints and potential of this device architecture. Collectively, these achievements open new horizons for the development of high-performance, tunable, and multi-band mid-infrared photodetectors, offering effective solutions for imaging, sensing, and optical communication applications.