Effective radius of curvature of truncated laser beams with amplitude modulation and phase fluctuation

Abstract

Usually, high-power laser beams are amplitude modulated and have phase fluctuations (PFs). The analytic formula of the effective radius R of curvature of truncated laser beams with amplitude modulations (AMs) and PFs propagating through atmospheric turbulence is derived by using the statistical optics method. It is shown that the R in free space increases with the increases of the phase fluctuation parameter, the intensity modulation parameter and the truncated parameter. And the influence of turbulence on the R also increases with the increases of the three parameters. Furthermore, the R of Gaussian beams is largest in free space, but it is most affected by turbulence. Therefore, in turbulence the R of truncated laser beams with AMs and PFs is even larger than that of Gaussian beams when the propagation distance is large enough. In particular, the relative effective radius Rr of curvature varies non-monotonically with propagation distance, and there exists a minimum at a propagation distance where the influence of turbulence on the R is largest. In addition, the position where the Rr reaches its minimum increases with the increasees of intensity modulation and phase fluctuation.

M2-factor of high-power laser beams through a multi-apertured ABCD optical system*

“…Meanwhile, the practical optical systems mostly are equipped with limited apertures which usually cause the laser beams propagating through these systems truncated. Thus, based on the mathematics model proposed by Manes and Simmons, a series of works concerning the propagation properties have been accomplished, [19][20][21][22][23][24][25] including M 2 factor of truncated high-power laser beams passing through turbulent atmospheric and passing through optical system with an aperture. The results showed that the propagation properties of high-power laser beams are related to both amplitude modulations and phase fluctuations when passing through optical system with an aperture.…”