Abstract
In this paper, the effects of turbulent biological tissues (TBT) on the propagation properties of the coherent Laguerre-Gaussian (CLG) beams are studied. Based on the turbulence theory and using the power spectrum refractive-index model, the expression formulae of the average irradiance intensity and spreading properties of a CLG beam propagating in TBT are derived. The influence of propagation distance, beam orders, wavelengths and tissue turbulence parameters are then investigated numerically. It found that, the central dark zone of the circular/elliptical LG beams rises more rapidly as the propagation distance and the structural constant of the refractive index of the biological tissue increase and the beams become eventually more like Gaussian beams in the far-field under the influence of the turbulence biological tissues. Also, the numerical results proved that the effective beam spot radius increases as turbulence, wavelength, and propagation distance are increasing. Ultimately, the beams become circular under the influence of the turbulence of the biological tissue. As found that the effective beam spot radius along the x-axis becomes equal to that of the y-axis in high TBT which explain why an elliptical LG beam is converted into a circular one in higher structural constant of the turbulent tissue. Moreover, our results show that, the influence of the beam order m slightly greater than that of l on the beam spreading.
Effect of the turbulent biological tissues on the propagation properties of coherent Laguerre-Gaussian beams