Scattering depolarization characteristics of 1064 nm nanosecond pulsed circularly polarized laser in near ground aerosol environments

Abstract Polarization detection is often affected by complex weather conditions, leading to deviations in test information. This is due to the scattering media such as water mist particles and gas molecules in the atmosphere that affect the transmission of polarized light waves. To address this issue, this paper, based on Mie scattering theory and Monte Carlo algorithm, established a multiple scattering transmission depolarization model for 1064 nm nanosecond pulse circularly polarized laser (NPCPL) in aerosol environments. It calculated the depolarization characteristics of polarized light in four typical nearground aerosol particles and analyzed the influence of pulse width, concentration, transmission distance, and particle radius on forward scattering depolarization. Based on simulation data, an exponential decay fitting model of degree of polarization (DOP) as a function of particle concentration, radius, and transmission distance is further proposed. The fitting determination coefficient R² reaches 0.952, indicating that this model can comprehensively reflect the influence mechanism of parameters such as particle concentration, radius, transmission distance, and refractive index on atmospheric transmission. The results show that affected by concentration, transmission distance, and particle radius, DOP shows a downward trend. This is because photons interact with the transmission medium and undergo scattering. The scattering direction directly determines the scattering intensity of the perpendicular and parallel components, and this difference in intensity leads to polarization. The pulse width has little effect on the DOP. This is because under the same power conditions, although narrow pulses correspond to a higher instantaneous photon number density, the probability of photonparticle scattering collisions is statistically the same, so changes in pulse width do not significantly affect the polarization state. The research findings of this article can provide a theoretical basis for applications of NPCPL in lidar, laser ranging, and wireless laser communication.