Propagation characteristics of the Kummer beam in turbulence with an anisotropic tilt angle

Abstract

Different from prevailing assumptions, turbulence cells display anisotropic tilt angles, rendering the environment in optical communication significantly more complex. In light of this, we develop expressions for the spatial coherence radius and the detection probability of the orbital angular momentum (OAM) states of the Kummer beam in turbulence with an anisotropic tilt angle. Through our investigation into the impact of various angles on optical communication, we identify suitable angles for mitigating the effects of atmospheric turbulence. Our findings indicate that when the zenith angle is equal to the anisotropic tilt angle and the azimuth angle is π, the disturbance of turbulence on the detection probability of OAM states is relatively weak. In slant paths, the variability in turbulence cells’ scales with altitude, particularly the inner scale, cannot be ignored. Consequently, a peak value emerges in the OAM detection probability owing to the variation of inner scales with altitude. Furthermore, the exponent of the amplitude factor and the logarithmic axicon parameter of the Kummer beam exhibit a significant impact on the received signal, especially at short propagation distances. We also investigate some other parameters of the turbulence and Kummer beam to enhance our comprehension of the propagation characteristics of a Kummer beam in a slant path. Overall, our results have practical implications in wireless optical communication systems such as remote sensing and radar communications.

Modulation effect of focusing mirror on beam propagation through anisotropic turbulence

“…= as reported in [12], the beam propagation direction is parallel to the short axis of the anisotropic turbulent cell. This configuration, under the assumption that anisotropic turbulence cells act as lenses [33], leads to a maximum reduction of the reflection index fluctuation and thereby achieves the best focus effect.…”

“…where 0 r represents the spatial coherence radius for assessing the condition of turbulence. When a beam transmits through a slant turbulence link involving the anisotropic tilt angle between turbulence cells and the ground, the corresponding spatial coherence radius, based on the modified Von Karman spectrum, can be determined [12].…”

“…L 0 and l 0 are respectively the outer and inner scales of atmospheric turbulence, and c A 2 2 52 3 . 9,12] are the anisotropic factors related to the anisotropic factor m which describes the ratio of the horizontal axis to the vertical axis of a turbulence cell. t is the angle between the short axis of the turbulence cell and the transmitted direction, it follows the form arccos cos cos sin sin cos 11…”

“…Building upon this research, Lin et al [11], first introduced the impact of anisotropic tilt angle in vertical ocean links and examined its effect on the scintillation index. In our previous work, we further investigated the impact of various angles on optical communication and studied the propagation characteristics of the Kummer beam in turbulence with an anisotropic tilt angle [12].…”