Impact of Divergence Angle on FSO System Performance: A Study of SNR, BER, and Q Factor

Context: Free Space Optics (FSO) transmission is a promising alternative to conventional wired networks, offering high bandwidth, low latency, and enhanced security. However, FSO performance is highly sensitive to physical factors, particularly the divergence angle of the optical beam. Objective: This study aims to evaluate the impact of beam divergence on key FSO system performance metrics to guide optimal system design. Method: MATLAB-based simulations were conducted to model Signal-to-Noise Ratio (SNR), Bit Error Rate (BER), and Q factor under varying divergence angles. The sensitivity of system performance to beam alignment and signal strength was analyzed across different divergence configurations. Results: Results indicate that smaller divergence angles provide higher SNR and Q factor values and lower BER, ensuring superior communication quality but requiring precise alignment. Conversely, larger divergence angles tolerate misalignment more effectively but at the cost of reduced signal quality. Conclusion: These findings emphasize the critical role of optimizing beam divergence to balance alignment tolerance and signal integrity, thereby enhancing the efficiency and reliability of optical wireless communication systems.