Self-Coherent Detection with Hermite-Gaussian Beams for Turbulence-Resilient Free-Space Optical Communication

Atmospheric turbulence severely degrades freespace optical (FSO) communication by inducing modal power coupling and wavefront distortion. This paper investigates a pilot-assisted self-coherent detection scheme to mitigate such impairments. A simulation framework is developed incorporating Hermite-Gaussian beams, multi-phase-screen turbulence modeling, and full-link quadrature amplitude modulation (QAM) modulation and digital signal processing (DSP) processing. By exploiting spatial coherence between co-propagating data and pilot beams, the scheme suppresses turbulence-induced distortion without explicit channel estimation. Simulation results demonstrate enhanced mode confinement and improved error vector magnitude (EVM) under varying turbulence levels, confirming the feasibility of self-coherent detection for robust FSO communication.