Scintillation calculations for partially coherent general beams via extended Huygens–Fresnel integral and self-designed Matlab function

Eyyuboğlu, Halil T.; Baykal, Yahya; Cai, Yangjian

doi:10.1007/s00340-010-4125-4

Cited by 20 publications

(5 citation statements)

References 52 publications

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“…where r 0 corresponds to the radius of receiver area, and the fourth order of the wave structure function is required for calculating average squared intensity, i.e., I 2 [18,19]. Figure 1 shows the experimental arrangement for measuring the scintillation of vortex beams in simulated turbulent atmosphere.…”

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confidence: 99%

Experimental investigation on the scintillation index of vortex beams propagating in simulated atmospheric turbulence

Chen

Ding

et al. 2012

Appl. Phys. B

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The scintillation index of vortex beam in simulated atmospheric turbulence is experimentally investigated. The fluctuation of the intensity can be effectively reduced by vortex beams. In particular, the reduction of scintillation is more pronounced for vortex beams with larger topological charge.Propagation of laser beams through turbulent atmosphere has attracted much attention because of their applications in many areas including free space optical communications, remote sensing, imaging systems, and laser radar. The intensity, degree of coherence, degree of polarization, beam spreading of the laser beams will be affected by the turbulence [1-3]. Among them, scintillation (i.e., the fluctuation of intensity) manifesting itself as signal dependent noise is one of the most important factors as the scintillation degrades the signal-to-noise ratio and may increase the bit error rate. The properties (beam shape, phase, polarization, coherence) of the incident beams strongly affect the scintillation. Therefore, it is of great importance to find a special light beam whose scintillation is less affected by turbulence. It has been indicated that the on-axis scintillation of an elliptical Gaussian beam and a dark hollow beam is smaller than that of a circular Gaussian beam in a weakly turbulent atmosphere under certain conditions [4,5]. The degradation of the degree of the source coherence may cause a significant reduction of scintillation index which means that the partially coherent beams are less affected by the turbulence than coherent beams [6]. An appropriately chosen nonuniformly polarized coherent beam is also demonstrated to have smaller scintillation than beams of uniform polarization [7]. Another solution for scintillation reduction is replacing the single incident beam by beam arrays. The scintillation of a beam array can be effectively reduced by adjusting the spatial separation of the beams [8].Beams with spiral phase are regarded as vortex beams, in which each photon carries orbital angular momentum (OAM) [9]. The OAM can be used to encode data onto a laser beam for transmitting information in free-space optical systems [10,11]. Such an application provides a possibility to increase the information density together with an inherent security enhancement [10]. The influence of the turbulent atmosphere on the OAM of the vortex beams has been investigated, and the results demonstrated that the OAM of the beam can be well preserved in a long propagation distance in weak turbulence [12]. The scintillation of vortex beams in turbulence has also been studied [13,14]. However, most of the studies have been limited to theoretical simulations [13]. Moreover, only vortex beams with topological charge n = 1 are considered in these papers [13,14]. In this study, we will focus on the scintillation of vortex beams in turbulence. The atmospheric turbulence is simulated by rotating a random phase plate. Both vortex beams with topological charge n = 1 and larger topological charge are investigated.Assume that the electric fi...

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confidence: 99%

Experimental investigation on the scintillation index of vortex beams propagating in simulated atmospheric turbulence

Chen

Ding

et al. 2012

Appl. Phys. B

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“…To eliminate the destructive effect of scintillation on laser beam transmission, different methods, such as increasing receiver aperture size, making phase correction via adaptive optics, using different laser beam such as different shape (Gaussian beam, Flat-topped beam, array beam,...) and different spatial coherence (partially and fully coherent laser beam), have been used in turbulent media [12,13,16,17,[20][21][22][23][24].…”

Section: Laser Physicsmentioning

confidence: 99%

“…The alternative method used to obtain the scintillation index is the extended Huygens-Fresnel integral, which is employed by many researchers basically for the coherent and partially coherent beams. It is worth mentioning that the extended Huygens-Fresnel method is somewhat superior to the Rytov method, since it is able to account for partially coherent beams as well as beams that contain zero on-axis intensity on the source plane [23,24].…”

Section: Laser Physicsmentioning

confidence: 99%

Scintillation and BER analysis of the partially coherent flat-topped array laser beam in the non-Kolmogorov atmospheric turbulence on slant path

Golmohammady¹,

Yousefi²,

Mashal³

et al. 2019

Laser Phys.

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Using the extended Huygens-Fresnel principle in this paper, a semi analytical expression for describing the on-axis scintillation index of a partially coherent flat-topped array laser beam through slant path of non-Kolmogorov atmospheric turbulence is derived; consequently, with the help of the log-normal intensity probability density function, the bit error rate (BER) is evaluated. The main aims of this paper are exploring the effects of source factors (such as wavelength, order of flatness, and beam width) and the non-Kolmogorov turbulent atmosphere parameters (such as Kolmogorov inner scale, general spectral power-law exponent, the turbulence structure constant) on propagation behaviour of scintillation index, and, hence, on BER. Results indicate that, when the average SNR increases, BER is more affected while the power-law exponent increases. Consequently, it can be deduced that the mean bit error rate increases while the power-law exponent decreases. In addition, the scintillation index and BER as communication link parameters represent the fact that increasing the atmospheric refractive-index structure parameter on the ground and decreasing the inner scale of turbulence eddies, which expresses the conditions of strong turbulence, causes an increase in theses link parameters.

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“…Up to now, although both the average irradiance and scintillation index of beams, radiated from spatially partially coherent sources, propagating in atmospheric turbulence have been investigated in detail [1,3,[8][9][10], the temporal characteristics of irradiance fading of these spatially partially coherent beams are rather unexplored. The Taylor frozen-turbulence hypothesis [10] has been widely used to study the temporal behavior of irradiance fluctuations induced by atmospheric turbulence.…”

Section: Introductionmentioning

confidence: 99%

Effects of source spatial partial coherence on temporal fade statistics of irradiance flux in free-space optical links through atmospheric turbulence

Chen¹,

Yang²,

Zhou³

et al. 2013

Opt. Express

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The temporal covariance function of irradiance-flux fluctua-tions for Gaussian Schell-model (GSM) beams propagating in atmospheric turbulence is theoretically formulated by making use of the method of effective beam parameters. Based on this formulation, new expressions for the root-mean-square (RMS) bandwidth of the irradiance-flux temporal spectrum due to GSM beams passing through atmospheric turbulence are derived. With the help of these expressions, the temporal fade statistics of the irradiance flux in free-space optical (FSO) communication systems, using spatially partially coherent sources, impaired by atmospheric turbulence are further calculated. Results show that with a given receiver aperture size, the use of a spatially partially coherent source can reduce both the fractional fade time and average fade duration of the received light signal; however, when atmospheric turbulence grows strong, the reduction in the fractional fade time becomes insignificant for both large and small receiver apertures and in the average fade duration turns inconsiderable for small receiver apertures. It is also illustrated that if the receiver aperture size is fixed, changing the transverse correlation length of the source from a larger value to a smaller one can reduce the average fade frequency of the received light signal only when a threshold parameter in decibels greater than the critical threshold level is specified.

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Scintillation calculations for partially coherent general beams via extended Huygens–Fresnel integral and self-designed Matlab function

Cited by 20 publications

References 52 publications

Experimental investigation on the scintillation index of vortex beams propagating in simulated atmospheric turbulence

Experimental investigation on the scintillation index of vortex beams propagating in simulated atmospheric turbulence

Scintillation and BER analysis of the partially coherent flat-topped array laser beam in the non-Kolmogorov atmospheric turbulence on slant path

Effects of source spatial partial coherence on temporal fade statistics of irradiance flux in free-space optical links through atmospheric turbulence

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