Scattering analysis of structured light beam for rainy atmosphere

This study is devoted to analyze the scattering from spherical homogeneous rain droplet particles illuminated by structured light beam i.e., Gaussian vortex beam (GVB) with different orbital angular momentum (OAM). The promising applications of intricate optical beam fields regarding environmental monitoring and detection have mesmerized the consideration of optical community. The optical effects i.e., absorption and scattering of the atmospheric environment cause intensity distribution of GVB which lowers quality of beam signal. GVB carries OAM and when it propagates in the atmosphere then its interaction with the environment constituents (rain, fog, snow, clouds, water vapours, atmospheric gases, and other particles) makes the problem quite interesting. Rainy medium is considered as a uniformly spherical shaped sphere. So, the interaction between a linearly polarized GVB and a rainy atmosphere is investigated using the generalized Lorenz–Mie theory (GLMT). The expressions for electromagnetic fields (incident + scattered + inside) of GVB are expanded using spherical vector wave functions (SVWFs). By implementing continuous boundary conditions (BCs) at the spherical surface of rain droplets, the scattering coefficients in context of beam shape coefficients are obtained. The efficiencies (scattering, extinction, and absorption), forward scattering, backward scattering, GVB attenuation as well as transmittance are computed and discussed. In addition to that, the influence of OAM mode number, beam waist radius, and incident beam operating wavelengths of rainy medium on the efficiencies, electromagnetic scattering, attenuation, and transmittance is analyzed. This study establishes the groundwork for examining the tuning capability of GVBs for rainy atmosphere at various parameters.