Propagation Characteristics of Partially Coherent Pin-Like Vortex Beams in Turbulent Biological tissues

This study examined the propagation characteristics of partially coherent pin-like optical (PCPO) vortex beams carrying orbital angular momentum (OAM) within turbulent biological tissues. The objective of this study was to assess the potential of these nanoparticles for deep-tissue optical communication and imaging. By incorporating the biological tissue turbulence spectrum into the analytical framework, we extended the established analytical expressions that describe the evolution of the OAM mode spectrum, spiral spectrum, and channel capacity of PCPO beams in inhomogeneous biological media, which were modeled using fractal-based turbulence power spectra. Numerical simulations were conducted for several representative tissues, including the upper dermis, deep dermis, liver parenchyma, and intestinal epithelium, to assess the impact of tissue heterogeneity parameters, spatial coherence length, and topological charge on beam stability. The findings indicate that the probability of OAM detection diminishes with propagation distance and increasing topological charge, whereas a greater spatial coherence length and larger characteristic heterogeneity length enhance the channel capacity. Biological tissues with higher fractal dimensions and lower correlation lengths exhibit more pronounced turbulence-induced degradation. When the coherence length exceeds approximately 10 μm, the detection probability becomes nearly invariant with distance, suggesting a regime of enhanced robustness. These results provide quantitative insights into the feasibility and limitations of employing partially coherent OAM beams for optical information transfer in biological tissues and offer theoretical guidance for designing OAM-based biomedical photonic systems.