A study of effects of a turbulent jet engine exhaust on partially coherent Laguerre-Gaussian Schell model vortex beam

Abstract

In this study, based on the generalized Huygens-Fresnel principle, the evolution properties, such as spectral density, degree of coherence, and beam width of the propagation of partially coherent Laguerre-Gaussian Schell model vortex beam (PCLGSMvB) in jet engine exhaust are studied. Our results show that the spectral density of the corresponding beam can change their form shape during its propagation as the source coherence varies. When the source coherence width is high, the profile of PCLGSMvB changes from initially dark hollow into two spot beams at short propagation distances. If the source coherent width is very small, the shape of PCLGSMvB is converted to a Gaussian shape and keeps its form upon propagation. Also, we found that the spreading of PCLGSMvB is related with their initial parameters, and it will be spread faster with smaller source coherence width, larger mode order n, and longer wavelength. Furthermore, the beam width of the PCLGSMvB increasing as the structural constant increases and it means that the beam can resist to stronger fluctuation of turbulence. Outputs of this study has potential application on deriving the requirements of optical systems on aircrafts like laser range finder, laser designator, optical communication systems and directed infrared countermeasure (DIRCM).