افزايش حساسيت در آشكارسازهاي نوري نيمرساناي تك فوتوني: اثر برهمكنش پلاسموني

Optical detectors are fundamental components in optoelectronic systems, responsible for converting incident optical energy into electrical signals. The development of these devices is closely tied to advances in the understan‎ding of light–matter interaction an‎d semiconductor technology. Over several decades, optical detectors have evolved from early thermal sensors to highly sensitive single-photon detectors. The advent of semiconductor materials, the development of PIN photodiodes, avalanche photodiodes (APDs), an‎d, more recently, superconducting nanowire single-photon detectors (SNSPDs), has significantly improved the speed, sensitivity, an‎d precision of modern detection systems. In recent years, plasmonics has emerged as a powerful platform for enhancing optical detection by enabling the confinement an‎d amplification of electromagnetic fields at the nanoscale. Plasmons—collective oscillations of free electrons in metals—allow light to be concentrated beyond the diffraction limit, thereby increasing field intensity an‎d absorption in semiconductor structures. The integration of plasmonic antennas, metallic nanoparticles, an‎d SPP waveguides with single-photon detectors has demonstrated remarkable improvements in quantum efficiency, polarization contrast, an‎d device miniaturization. These advancements have opened new pathways for plasmonic–quantum technologies in applications such as single-photon LiDAR, quantum-secure communications, an‎d ultra-sensitive biomedical imaging. This thesis first reviews the fundamentals of optical detectors an‎d single-photon detection mechanisms, followed by an introduction to plasmonic theory—including surface plasmon polaritons, localized surface plasmons, an‎d excitation techniques. The role of plasmonic structures in controlling an‎d enhancing light–matter interactions on the nanoscale is analyzed in detail. In the practical section, a plasmon-enhanced PIN photodiode structure is proposed an‎d simulated using COMSOL Multiphysics. The simulation results indicate that incorporating plasmonic elements significantly increases optical absorption in the active layer, enhances the local electric field, an‎d improves both responsivity an‎d quantum efficiency. Finally, the thesis discusses the advantages an‎d limitations of the proposed design an‎d provides recommendations for future research, particularly toward CMOS-compatible integrated photonic an‎d quantum detection systems.

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