Research on Beam Expansion Characteristic of Supercontinuum Laser in Atmospheric Turbulence

Considering the difference in the divergence angle of different spectral components of supercontinuum laser, this paper researched the beam expansion effect of supercontinuum laser in atmospheric turbulence. The simulated laser transmission is carried out in the Von Karman model. The influence of turbulence of different intensities on the beam expansion is compared, the influence of turbulence on supercontinuum laser beam expansion with vertical, slant and horizontal transmission are also studied. The results show the beam expansion effect of strong turbulence on the short- wavelength part of supercontinuum laser is more obvious than that of moderate turbulence and weak turbulence. As the intensity of turbulence increases, the spot of the short-wavelength part increases rapidly first and then increases slowly and steadily, the spot of the long-wavelength part keeps almost unchanged at first, and also then increases slowly and steadily. The relationship between the elevation angle of laser beam emission and the beam width is calculated, and three cases are specifically analyzed. In the cases of vertical transmission and slant transmission, the beam width is related to the characteristics of the light source after collimation, which increases with the increase of the wavelength. When the laser is transmitted horizontally, the beam width has been greatly expanded, especially in the short-wavelength part. As the angle increases, the radius of the spot decreases rapidly first and then keeps almost unchanged. The radius of the spot of the short wavelength part reduces a larger proportion than that of the long-wavelength part.