Propagation of various dark hollow beams in a turbulent atmosphere

KTH Royal Institute of Technology, Tukholma, Stockholm, Sweden
Optics Express (Impact Factor: 3.53). 03/2006; 14(4):1353-67. DOI: 10.1364/OE.14.001353
Source: PubMed

ABSTRACT Propagation of a dark hollow beam (DHB) of circular, elliptical or rectangular symmetry in a turbulent atmosphere is investigated. Analytical formulas for the average intensity of various DHBs propagating in a turbulent atmosphere are derived in a tensor form based on the extended Huygens-Fresnel integral. The intensity and spreading properties of the DHBs in a turbulent atmosphere are studied numerically. It is found that after a long propagation distance a dark hollow beam of circular or noncircular eventually becomes a circular Gaussian beam (without dark hollow) in a turbulent atmosphere, which is much different from its propagation properties in free space. The conversion from a DHB to a circular Gaussian beam becomes quicker and the beam spot in the far field spreads more rapidly for a larger structure constant, a shorter wavelength, a lower beam order and a smaller waist size of the initial beam.

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Available from: Yangjian Cai, Dec 21, 2014
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    • "A number of works have been carried out concerning the propagation of different kinds of laser beams in a turbulent atmosphere. In this medium, Cai and He have been studied the propagation of various dark hollow beams [5], Alavinejad et al. have been emphasized the analysis of the propagation of flat-topped beams with various orders [6], Eyyuboglu and Baykal have been investigated the properties of cos- Gaussian, cosh-Gaussian laser beams [7] [8], Belafhal et al. have been studied the propagation of truncated Bessel-Modulated Gaussian beams [9], and Zhou et al. have been analyzed the propagation of a Hermite–Laguerre–Gaussian beam [10]. Newly, such a new type of laser beams called the superposition of Kummer beams (SKBs) were introduced by Khannous et al. and Ez-zariy et al. [11] [12], which are doughnut beams generated by a Spiral Phase Plate illuminated by flattened-Gaussian beams, whose propagation in a turbulent atmosphere has not been studied. "
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    ABSTRACT: In this paper, the propagation of the superposition of Kummer beams (SKBs) in a turbulent atmosphere is investigated. Analytical axial intensity of the SKBs is derived by using the extended Huygens-Fresnel integral formula in the paraxial approximation, and based on the expression of the hard aperture. Utilizing the analytical expression, numerical calculation is explored. Results show that the axial intensity distribution changes with the variation of the order N, the topological charge, the wavelength, the beams waist width, and for different values of the turbulence strength. The average intensity of flattened-Gaussian and the fundamental Gaussian beams has been extracted, as a special case from the obtained results. Our present study shows that the axial intensity distribution of these beams family depends on the variation of the turbulent strength and the parameters of the initial field.
    Physical and Chemical News 07/2014; 73:83-89. · 0.11 Impact Factor
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    • "Due to their wide applications in optical trapping atoms [1] [2], optical tweezers [3] and optical metrology [4], dark hollow beams (beams with zero central intensity) have received increased interest in the past few years [5] [6]. Of these, since its introduction by Cai et al. [7] as new kind of dark hollow beams, the hollow- Gaussian beam (HGB) has been the subject of a lot of investigations. "
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    ABSTRACT: Based on the generalized Collins-Huygens diffraction integral, and by means of the expansion of a hard aperture function into a finite sum of complex Gaussian functions a main approximate analytical expression of hollow-Gaussian light, propagating through a paraxial ABCD optical system coupled with an annular aperture, is devoted in this paper. The corresponding closed-forms of the transformation of a hollow-Gaussian beam (HGB) by an unapertured ABCD optical system, and by this last coupled with a circular aperture or circular black screen are also treated in this work as particular cases of the principal finding. After propagating in optical systems cited above, it is observed that the HGB will be transformed into a Laguerre-Gaussian beam. From these results, we found the previous study concerning the propagation of pure Gaussian laser light through the above optical systems. Using the analytical expressions, the transverse intensity distribution of propagation characteristics in the annular aperture, and in black screen are discussed and investigated numerically in detail in this work.
    Physical and Chemical News 07/2014; 73:30-38. · 0.11 Impact Factor
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    • "Dark hollow beams (DHBs) having zero on axis intensity in space surrounded by light have attracted much interest in the past decade owing to their potential applications in atomic optics [1], free-space optical (FSO) communication [2] [3] and biological sciences [4]. Various techniques have been proposed to generate hollow beams [5] [6] [7], and different kinds of hollow beams have been studied so far [3, 8–10]. "
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    ABSTRACT: An experimental study is carried out to investigate the effect of coherence and polarization on the polychromatic partially coherent dark hollow beam (PCDHB). The experimental results show that the spatial coherence and source polarization affect the dark region of the generated hollow beam. The study shows that by varying the source degree of polarization (DOP), we get a tunable dark region. We find that the longer the spatial coherence length of the input beam, the larger the central dark size of the resultant PCDHB. Further, it is shown that polychromatic PCDHB with low spatial coherence travel a longer distance without being distorted than a beam with a high spatial coherence. These kinds of polychromatic beams may find potential application in the field of polychromatic light based free-space optical (FSO) communications.
    Journal of optics 06/2014; 16(7):075402. DOI:10.1088/2040-8978/16/7/075402 · 2.01 Impact Factor
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