Superconducting Nanowire Single-Photon Detectors (SNSPDs) are the most prominent and versatile technology for single-photon counting at near-infrared (NIR) wavelengths. Through the introduction of specialized superconducting materials, SNSPDs have also been demonstrated at mid-infrared (MIR) wavelengths. However, reaching the same performances at this range remains an elusive goal. For example, traditional methods for enhancing optical absorption, such as optical cavities, are practically not suitable at longer wavelengths due to the large thickness required. This thesis proposes a novel detector architecture that combines the resonant plasmonic perfect absorber effect with a fractal metasurface to achieve high-efficiency, broadband, and polarization-insensitive single photon absorption and detection in the MIR.