Study of optical field distribution in turbulent channels for wireless ultraviolet optical communications

The optical field distribution of ultraviolet transmission through scattering in atmospheric channels clearly reflects the energy distribution throughout the process. This paper established and analyzed an optical field distribution model for turbulent ultraviolet channels. Using this model, we calculated the energy of photons reaching sampling points after single and multiple scattering events, and characterized the optical field distribution of ultraviolet scattering transmission in turbulent channels. The influences of elevation angle, divergence angle, and altitude on the optical field distribution of turbulent channels were then analyzed. Results from Monte Carlo simulations demonstrate that in the X-Z plane, the turbulent channel's light field distribution is no longer axisymmetric about the center of the emitting light cone, due to the different altitudes of the sampling points. In addition, elevation angles significantly impact the light field distribution. A larger elevation angle results in wider contour spacing in the light field. In the X-Y plane light field distribution, a higher elevation angle shifts contour lines of the same path loss value closer to the transmitter along the X-axis. Conversely, a larger divergence angle moves those contour lines closer to the transmitter along the X-axis while gradually widening them along the Y-axis. When the geometric parameters of the transmitter remain constant, the light field distribution in the X-Z and X-Y planes at different altitudes reveals that the turbulence effect on photon transmission decreases as the altitude increases. Finally, experiments were conducted to measure the received energy at the sampling points of the light field. We compared the experimental results to the simulation results for both turbulent and non-turbulent scenarios, and confirmed the accuracy of our model presented in the paper.