Evaluation of binary polarization-based signal modulation for laser communications in turbulence

Laser communication link performance in free space depends heavily on atmospheric conditions present on the propagation path. Distortions due to atmospheric turbulence, such as scintillation and beam wander, greatly diminish signal detection and performance. With the final goal of improving the communication link, we examine the numerical efficiency of optical binary polarization-based signal modulation (B-PolSK) along a simulated atmospheric horizontal propagation path and compare it with a laboratory-based experimental arrangement of B-PolSK employing a polarizing beam splitter and two amplified photodetectors. Additionally, we present experimental measurements of free-space propagation through a 1-km path. By computing the ratio of detected intensities, the linear polarization state can be directly identified, making this method particularly beneficial for FSO links, where it is crucial to mitigate rapid atmospheric disturbances in real time. This setup avoids the necessity for moving components or rotation stages, thus enabling continual monitoring of polarization fluctuations. We assess the system's performance under different turbulence conditions to determine its practical applicability.