The transmission characteristics of rotationally-symmetric power-exponent-phase vortex beams in biological tissue

The transmission characteristics of rotationally symmetric power-exponent-phase vortex beams (RSPEPVBs) in biological tissues are explored in this study. Based on the extended Huygens-Fresnel principle, a general expression describing the transmission of RSPEPVBs through biological tissues is established. Numerical simulations are performed to explore the influence of the propagation distance z, power exponent n, wavelength λ, and beam waist width w on light intensity, beam width, and beam divergence. The findings reveal that increasing the propagation distance and wavelength results in greater beam diffusion and an enlarged beam width. Conversely, a higher power exponent concentrates the light intensity toward the center and mitigates the broadening of the beam width. Additionally, a longer wavelength and smaller beam waist width lead to a larger beam divergence angle. The evolution of coherence vortices and intensity peak positions with increasing propagation distance is also analyzed, revealing a gradual outward displacement from the beam center, accompanied by angular deviations and positional shifts. Notably, when the topological charge l ≥ 4, the position of the peak point undergo an abrupt shift during the transmission process. As a high-order mode beam, the transmission of RSPEPVBs in biological tissues exhibits diversity and controllability, opening up new possibilities for micro-manipulation technologies in the biomedical field.