Vortex optical field is widely used in optical communication, particle control, quantum information and other fields due to its special physical structure. Coherence is an important inherent property of the beam, with unique advantages in resistance to speckle noise and atmospheric turbulence disturbance. In this paper, taking the cosine-Gaussian correlation function as an typical example, a mathematical model of the cosine-Gaussian-correlated Schell model vortex (CGCSMV) source is established. Using the extended Huygens-Fresnel integral, and the generalized anisotropic turbulence spectral model, we derive an analytical expression for the far-field cross spectral density function of a CGCSMV beam propagating in anisotropic turbulence. Lastly, we perform numerical simulations of the behaviors of the far-field spectrum of our beam. The results of this paper have some practical reference value for the new optical field regulation, optical communication and lidar system.
Based on angular spectrum expansion and 4x4 matrix theory, our works have combined the traditional vortex optical theory with the latest Topological insulator (TI) to present the reflection and transmission characteristics of an Laguerre Gaussian (LG) beam from a multilayered topological insulator slab. The reflected and transmissed beam intensities from three-layered TI slab are numerically simulated. It is shown that the distortion of intensity distribution is greatly affected by the topological magneto-electric polarizability of TI. The method presented in this article not only colud be extended to different TI-layers but could reveal unusual photonic band structures and band gaps in TI photonic crystals in further research.
Cirrus scattering is not only related to the angle of incidence, the angle of scattering, the wavelength, and the polarization state of the light, but also closely related to the roughness of the subsurface of the ice crystal. In this paper, we study different hexagonal plate-shaped ice crystals that are subject to standard gamma distribution with smooth, moderately rough and severe roughness.Scattering characteristics such as extinction coefficient, absorption coefficient and phase matrix of the cirrus cloud are compared to compare the effects of ice crystallites on the scattering characteristics under different surface roughness. The results show that under the same conditions, the rougher the surface of the ice crystals, the smaller the extinction coefficient and the single scattering albedo of the cirrus, the larger the absorption coefficient of the cirrus; the smoother the curve of the six elements of the phase function, the phase matrix The impact is also greater. Therefore, the surface roughness of the ice crystal grains has a great influence on the bulk scattering characteristics of the cirrus clouds. The work done in this paper will further study the influence of the surface roughness of ice crystals on the radiation transmission characteristics of cirrus clouds and the bulk scattering and radiation transmission characteristics of cirrus clouds. It is of great significance for target detection, tactical applications and free-space optical communication.
Changes in the polarization properties of a spatially and spectrally partially coherent stochastic electromagnetic Gaussian Schell-model (EGSM) ultrashort pulse laser beam propagating through the atmospheric turbulence are investigated. We derive analytic equations for the spectral degree of polarization and the polarization angle in terms of the extended Huygens-Fresnel principle and elements of the 2×2 cross-spectral density function matrix of the electric field. Within the framework of the Tatarskii model of the turbulent atmosphere, which taking the inner scale of the turbulent eddies into consideration, the dependence of along the z-axis and off the z-axis the spectral degree of polarization and the polarization angle of a stochastic EGSM ultrashort pulse laser beam on the parameters of the source including spatial coherence length and temporal coherence length are stressed and illustrated numerically. Results show that the spectral degree of polarization and the polarization angle of the EGSM ultrashort pulse laser beam propagating through the atmospheric turbulence are determined by the parameters of the source. Our results have potential applications in atmospheric remote sensing and ground-to-satellite optical communications.
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