multi-Gaussian Schell-model Vortex Research Articles

The effective beam width of a partially coherent rectangular mul-ti-Gaussian Schell-model vortex beam propagating in a turbulent plasma

Based on the derived analytical formulae for the optical intensity and effective beam width of a partially coherent rectangular multi-Gaussian Schell-model (RMGSM) vortex beam, we analyzed the evolution of the effective beam width of a partially coherent RMGSM vortex beam propagating in an anisotropic turbulent plasma using numerical examples. The numerical results demonstrated that the effective beam widths in the x and y directions were similar. In studies on the influences of the source parameters, one can see that an RMGSM vortex beam with a larger topological charge and beam waist or a smaller correlation coefficient σ evolves into a beam with a larger effective beam width. However, the influence of beam order was not evident. In addition, numerical examples proved that the effective beam width increases with increasing propagation distance and refractive index fluctuation variance or decreasing anisotropy parameter , outer scale , and inner scale . This study's results will be beneficial for applications in free-space optical communications.

Vortex phase induced evolution of propagation properties of a spatiotemporally partially coherent partially polarized pulsed beam in atmospheric turbulence

Here, a novel family of stochastic electromagnetic sources called spatiotemporally partially coherent partially polarized multi-Gaussian Schell-model vortex pulsed beams is proposed. With the extended Huygens–Fresnel principle, we derive the analytical formulas for the propagation of our beam in atmospheric turbulence. The spectral density and spectral degree of polarization of such beam both in free space and atmospheric turbulence are investigated. For comparison, we also study the behavior of the partially polarized multi-Gaussian Schell-model non-vortex pulsed beams during transmission. Our theoretical models enrich the classical theory of propagating stochastic electromagnetic beams and may provide a feasible method for further explorations to the novel kind of optical field modulation.

Intensity and Coherence Characteristics of a Radial Phase-Locked Multi-Gaussian Schell-Model Vortex Beam Array in Atmospheric Turbulence

The theoretical descriptions for a radial phase-locked multi-Gaussian Schell-model vortex (RPLMGSMV) beam array is first given. The normalized intensity and coherence distributions of a RPLMGSMV beam array propagating in free space and atmospheric turbulence are illustrated and analyzed. The results show that a RPLMGSMV beam array with larger total number N or smaller coherence length σ can evolve into a beam with better flatness when the beam array translating into the flat-topped profile at longer distance z and the flatness of the flat-topped intensity distribution can be destroyed by the atmospheric turbulence at longer distance z. The coherence distribution of a RPLMGSMV beam array in atmospheric turbulence at the longer distance will have Gaussian distribution. The research results will be useful in free space optical communication using a RPLMGSMV beam array.

Propagation of a rectangular multi-gaussian schell-model vortex beam in uniaxial crystal

The cross-spectral density of a rectangular multi-Gaussian Schell-model vortex beam propagating in uniaxial crystal orthogonal to the optical axis has been derived, and the normalized intensity and effective beam widths are investigated by using numerical analysis. The results indicate that the rectangular multi-Gaussian Schell-model vortex beam propagating in uniaxial crystal will evolve from circular dark hollow beam into an elliptical flat-topped beam due to the influences of uniaxial crystal. The effective beam width Wx will gradually increase as the propagation distance z increase, and the beam with larger M and N1=N2 or smaller σ will have a larger effective beam width Wx at the same propagation distance.

Spreading properties of a multi-Gaussian Schell-modelvortex beam in slanted atmospheric turbulence

The cross-spectral density function of a multi-Gaussian Schell-model vortex (MGSMV) beam propagating through slanted atmospheric turbulence was derived, and the influences of the MGSMV beam parameter and slanted atmospheric turbulence on the spreading properties of a MGSMV beam are studied. One can find that a MGSMV beam propagating in slanted atmospheric turbulence can evolve into the flat-topped beam, and a MGSMV beam with larger index N and topological charge M propagating in slanted atmospheric turbulence will lose the dark hollow center and evolve into the Gaussian beam more slowly than the MGSMV beam with smaller index N and topological charge M. It is also found that a MGSMV beam propagating in slanted atmospheric turbulence with larger strucutre parameter C will evolve into Gaussian beam faster, but the influences of zenith angle α on the spreading properties of MGSMV beam in the far field can be ignored.

Evolutions of random electromagnetic multi-Gaussian Schell-model vortex beams propagating in uniaxial crystals orthogonal to the optical axis

The analytical expressions of random electromagnetic multi-Gaussian Schell-model vortex beams propagating in uniaxial crystals orthogonal to the optical axis are derived. The effects of ratio of extraordinary index to ordinary index of uniaxial crystal on propagation properties of random electromagnetic multi-Gaussian Schell-model vortex beam are discussed by using numerical simulations. It is shown that the circular symmetry of random electromagnetic multi-Gaussian Schell-model vortex beam will translate into elliptical symmetry due to the influences of uniaxial crystal, and the beam propagation in uniaxial crystal with larger ratio of extraordinary index to ordinary index will evolve into an elliptical flat-topped beam with larger width along x-axis.

Propagation of rectangular multi-Gaussian Schell-model vortex beams in turbulent atmosphere

Based on the extended Huygens-Fresnel integral, the analytical expression of average intensity of a rectangular multi-Gaussian Schell-model vortex (RMGSMV) beam propagating in turbulent atmosphere is derived, the effects of turbulent atmosphere on the average intensity and effective beam widths of a RMGSMV beam are analyzed. The numerical results indicate that the RMGSMV beam propagating in turbulent atmosphere will gradually evolve from the dark hollow beam into a solid beam with Gaussian-like distribution, and the effective beam width Wxz of a RMGSMV beam propagating in turbulent atmosphere with larger Cn2 will have a larger beam width. The results also show that the effective beam width of a RMGSMV beam with smaller σ, larger M and N1=N2 will have a larger effective beam width as the propagation distance increases.

Model of a rectangular multi-Gaussian Schell-model vortex beam and its properties

Considering the theory of coherence, the rectangular multi-Gaussian Schell-model vortex beam (RMGSMV) beam generated by multi-Gaussian Schell-model source has been introduced, and the propagation properties of RMGSMV beam propagating in free space has been analyzed by using the derived equations. The effects of beam parameters on the properties of RMGSMV beam propagating in free space have been discussed. The results show that the RMGSMV beam propagating in free space can remain the dark hollow center at the short propagation distance, and the beam will gradually evolve into a beam with similar rectangular flat-topped profile as the propagation distance increases.

Electromagnetic multi-Gaussian Schell-model vortex light sources and their radiation field properties

A procedure for modeling the general electromagnetic Schell-model vortex light source is proposed. Based on this method, we introduce a new class of stochastic electromagnetic vortex light sources with multi-Gaussian Schell-model coherence function. The far-field statistical properties of the beams generated by such sources are studied in detail by numerical examples. Our results can be used to determine the mode structure of a new class of stochastic electromagnetic vortex light sources and of the radiation fields generated by them.

Influences of uniaxial crystal on partially coherent multi-Gaussian Schell-model vortex beams

The evolution properties and the spectral degree of coherence of a partially coherent multi-Gaussian Schell-model vortex (MGSMv) beam propagating in uniaxial crystals orthogonal to the optical axis are studied. Propagation expression for the cross-spectral density and the average intensity of the partially coherent MGSMv beam propagating in uniaxial crystals are derived. Some analyses are illustrated by numerical examples related to the propagation properties and coherence vortices of the partially coherent MGSMv beam in uniaxial crystals. Numerical results show that, upon propagating in uniaxial crystals, the partially coherent MGSMv beam loses its initial dark center distribution. After propagating for sufficient distances, the partially coherent MGSMv beam will also evolve into a flat-topped beam. The evolution behavior of average intensity and coherent vortices depends on the crystal including the ratio of extraordinary and ordinary refractive indices, and beam parameters including the spatial correlation length and topological charge of the beams, as well as the propagation distance.

Spreading and evolution behavior of coherent vortices of multi-Gaussian Schell-model vortex beams propagating through non-Kolmogorov turbulence

The explicit closed-form expressions for the beam width and angular spread of multi-Gaussian Schell-model vortex (MGSMV) beams propagating through atmospheric turbulence are derived in this paper. The spreading and evolution behavior of coherent vortices of MGSMV beams in non-Kolmogorov turbulence are investigated quantitatively by some typical numerical examples, where the evolution behavior of coherent vortices is stressed in particular. It is illustrated that MGSMV beams are more resistant to atmospheric turbulence than multi-Gaussian Schell-model (MGSM) non-vortex beams. By increasing the beam index of MGSMV beams, the deleterious turbulence effects can be reduced gradually. As MGSMV beams propagate in non-Kolmogorov turbulence, the position and number of coherent vortices are changeable. The impact of the beam index and fluctuations of atmospheric turbulence on the conservation distance of the topological charge is also explored in depth.

Multi-Gaussian Schell-model vortex beam

Abstract Multi-Gaussian Schell-model (MGSM) beam was introduced recently (Sahin and Korotkova, 2012 [34] , and Korotkova et al., 2012 [35] ). In this paper, multi-Gaussian Schell-model vortex (MGSMV) beam is introduced as a natural extension of MGSM beam. The explicit expression for the cross-spectral density of a MGSMV beam propagating through a stigmatic ABCD optical system is derived and the focusing properties of a MGSMV beam are studied in detail. It is found that we can shape the focused beam profile by varying the initial beam parameters, which will be useful in material thermal processing and particle trapping.