Coupling efficiency of a partially coherent collimating laser from turbulent biological tissue to fiber

We propose a model of the fiber coupling efficiency for a partially coherent collimating laser beam propagating through turbulent biological tissue to fiber. By studying the influence of link parameters on fiber coupling efficiency, we find that there are optimal focal length and transmitting beam radius for specific turbulent tissue. We also find that a larger characteristic length and small length-scale factor, or smaller fractal dimension and strength coefficient of refractive-index fluctuation will lead to larger fiber coupling efficiency. In order to improve the fiber coupling efficiency, we recommend select the optimum focal length, moderate transmitting beam radius, lower aperture diameter of the coupling lens, longer wavelength and higher coherent degree of light source. 2000 MSC: 41A05, 41A10, 65D05, Keywords: Fiber coupling efficiency, Biological tissue, Turbulence, Optimum parameter, Laser beam