Physical Science International Journal

Free-Space Optical Communication (FSO) has emerged as a promising solution for next-generation wireless networks, offering ultra-high bandwidth, security, scalability and interference-free transmission. However, its performance remains highly sensitive to atmospheric turbulence and photodetector characteristics. This paper presents a unified analytical and numerical framework for evaluating the performance of three major photodetectors namely Positive-Intrinsic-Negative (PIN) photodetectors, Avalanche Photodiode (APD), and Single-Photon Detector (SPD) under M´ alaga-distributed turbulence, a generalized model encompassing weak to strong scintillation regimes. Unlike other turbulence models that are limited to a specific scenario, the M´alaga distribution is evolutionary, capturing a wide range of realistic and dynamically varying atmospheric conditions, which provides a more comprehensive and practical basis for assessing FSOC system performance. The formulation integrates geometric and atmospheric attenuation, turbulence-induced irradiance fluctuations, and detector-specific gain and noise mechanisms to assess key performance metrics including Signal-to-Noise Ratio, Symbol Error Rate, noise variance, dynamic range, and linearity. Simulation results show that the SPD achieves the highest sensitivity and longest range, maintaining an SNR of 15 dB and an SER near 10−6 up to 50-55 km, followed by the APD (≈30 km) and PIN (≈25 km). The PIN exhibits the lowest noise ( 10−10 A) and widest dynamic range (70 dB), whereas the APD provides the most stable linearity. These findings align with and extend existing literature by combining M´alaga turbulence modeling with detector-level physical analysis and Monte Carlo validation. The results establish clear operational domains for each detector type and provide a practical foundation for the design of robust, high-performance FSOC systems resilient to atmospheric
impairments.