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ABSTRACT: It is well known that atmospheric turbulence causes significant variations of the arrival angle of laser beams used in free-space
communications. Usually, angle-of-arrival fluctuations of an optical wave in the plane of the receiver aperture is calculated
by Kolmogorov’s power spectral-density model. Unfortunately, recently increasing experimental evidence has shown that atmospheric
turbulence statistics does not obey Kolmogorov’s power spectrum model in some parts of the troposphere and stratosphere. These
experiments have prompted investigations of the optical-wave propagation through atmospheric turbulence described by nonclassical
power spectra. In this paper, employing a new approach and considering a non-Kolmogorov power spectrum with a generalized
power law instead of the constant standard power-law value 11/3 and a generalized amplitude factor instead of the constant
value 0.033, we derive the variances of the angle-of-arrival fluctuations of the plane and spherical waves in a weak turbulence
for the horizontal path. The concise closed-form expressions are obtained and used to analyze the influence of spectral power-law
variations on the angle-of-arrival fluctuations. In addition, the outer scale effect is also analyzed.
Journal of Russian Laser Research 04/2012; 30(6):552-559. · 0.75 Impact Factor
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ABSTRACT: Nowadays it has been accepted that the Kolmogorov model is not the only possible turbulent one in the atmosphere, which has been confirmed by the increasing experimental evidences and some results of theoretical investigation. This has prompted the scientist community to study optical propagation in non-Kolmogorov atmospheric turbulence. In this paper, using a non-Kolmogorov power spectrum which has a more general power law instead of standard Kolmogorov power law value 11/3 and a more general amplitude factor instead of constant value 0.033, the temporal power spectra of the presentative amplitude and phase effects, irradiance and angle of arrival fluctuations, have been derived for horizontal link in weak turbulence. And then the influence of spectral power-law variations on the temporal power spectrum has been analyzed. It is anticipated that this work is helpful to the investigations of atmospheric turbulence and optical wave propagation in the atmospheric turbulence.
Optics Express 03/2010; 18(6):5763-75. · 3.59 Impact Factor
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ABSTRACT: A laser transmission experiment is conducted to examine atmospheric turbulence-induced angle-of-arrival fluctuations over an 11.8 km urban path. The variance of fluctuations, probability density function, power spectrum, and Fried coherence length are investigated based on the analysis of the experimental data collected in each season of a year, respectively. In addition, the daily variations characteristic of path-averaged optical turbulence intensity Cn2 is also studied. At last, the aperture averaging theory is validated. It is anticipated that this work is helpful to the research of optical wave atmospheric propagation and the design of free-space laser optics communication systems.
Laser and Particle Beams 02/2010; 28(01):91 - 99. · 1.62 Impact Factor
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ABSTRACT: In the past decades, both the increasing experimental evidences and some results of theoretical investigation on non-Kolmogorov turbulence have been reported. This has prompted the study of optical propagation in non-Kolmogorov atmospheric turbulence. In this paper, using a non-Kolmogorov power spectrum which owns a generalized power law instead of standard Kolmogorov power law value 11/3 and a generalized amplitude factor instead of constant value 0.033, the log-amplitude variances for a Gaussian-beam wave are derived in the weak-fluctuation regime for a horizontal path. The analytic expressions are obtained and then used to analyze the effect of spectral power-law variations on the log-amplitude fluctuations of Gaussian-beam wave.
Optics Express 01/2010; 18(2):451-62. · 3.59 Impact Factor
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ABSTRACT: Based on weak fluctuation theory and the beam-wander model, the bit-error rate of a ground-to-satellite laser uplink communication system is analyzed, in comparison with the condition in which beam wander is not taken into account. Considering the combined effect of scintillation and beam wander, optimum divergence angle and transmitter beam radius for a communication system are researched. Numerical results show that both of them increase with the increment of total link margin and transmitted wavelength. This work can benefit the ground-to-satellite laser uplink communication system design.
Optics Letters 12/2008; 33(22):2611-3. · 3.40 Impact Factor
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ABSTRACT: An 11.8km optical link is established to examine the intensity fluctuation of the laser beam transmission through atmosphere turbulence. Probability density function, fade statistic, and high-frequency spectrum are researched based on the analysis of the experimental data collected in each season of a year, including both weak and strong fluctuation cases. Finally, the daily variation curve of scintillation index is given, compared with the variation of refractive-index structure parameter C(n) (2), which is calculated from the experimental data of angle of arrival. This work provides the experimental results that are helpful to the atmospheric propagation research and the free-space optical communication system design.
Optics Express 06/2008; 16(10):6963-73. · 3.59 Impact Factor
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ABSTRACT: Recently the increasing experimental evidences have shown that atmospheric turbulence statistics does not obey Kolmogorov’s power spectrum model in portions of the troposphere and stratosphere. These experiments have prompted the investigations of optical wave propagation through atmospheric turbulence described by non-classical power spectra. In this paper, using an original approach and considering a non-Kolmogorov power spectrum which uses a generalized power law instead of constant standard power law value 11/3 and a generalized amplitude factor instead of constant value 0.033, the variances of the angle-of-arrival fluctuations of the plane and spherical waves are derived in weak turbulence for a horizontal path. The concise closed-form expressions are obtained and used to analyze the influence of spectral power law variation on the angle-of-arrival fluctuations.
Optics Communications 282(5):705-708. · 1.49 Impact Factor
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ABSTRACT: Packet error rate of OOK, DPIM and PPM modulation schemes are researched for ground-to-satellite optical communication systems. Analysis process is based on threshold detection for OOK and DPIM, and optimal detection for PPM. Packet error rate of these three modulation schemes are compared for both uplink and downlink, with consideration of the turbulence introduced intensity fluctuation in the ground-to-satellite laser link. Numerical results are given, and based on it, the advantages of PPM and DPIM are discussed, with the comparison to OOK. This work can be helpful for modulation scheme selection in the ground-to-satellite laser communication system design.
Optics Communications 283(2):237-242. · 1.49 Impact Factor
