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Partially coherent Gaussian–Schell model pulse beam propagation in slant atmospheric turbulence

Chinese Physics B 2014年第6期23卷 295-303页

作者：李亚清吴振森张元元王明军 School of Physics and Optoelectronic Engineering Xidian University School of Physics and Electronic Engineering Xianyang Normal College

Based on the extended Huygens-Fresnel principle, a two-frequency, two-point cross-spectral density function of partially coherent Gaussian-Schell model pulse （GSMP） beam propagation in slant atmospheric turbulence is derived. Using the Markov approximation method and on the assumption that （w1 - w2）/（w1 ＋ w2） ≤ 1, the theory obtained is valid for turbulence of any strength and can be applied to narrow-band signals. The expressions for average beam intensity, the beam size, and the two-frequency complex degree of coherence of a GSMP beam are obtained. The numerical results are presented, and the effects of the frequency, initial pulse width, initial beam radius, zenith angle, and outer scales on the complex degree of coherence are discussed. This study provides a better understanding of the second-order statistics of a GSMP beam propagating through atmospheric turbulence in the space-frequency domain.

关键词： atmospheric propagation partial coherence atmospheric turbulence

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Scintillation of partially coherent Gaussian–Schell model beam propagation in slant atmospheric turbulence considering inner- and outer-scale effects

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Chinese Physics B 2014年第7期23卷 409-416页

作者：李亚清吴振森张元元王明军 School of Physics and Optoelectronic Engineering Xidian University School of Physics and Electronic Engineering Xianyang Normal College

Based on the modified Rytov theory and the international telecommunication union-radio （ITU-R） slant atmospheric structure constant model, the uniform scintillation index of partially coherent Gaussian-Schell model （GSM） beam propa- gation in the slant path is derived from weak- to strong-turbulence regions considering inner- and outer-scale effects. The effects of wavelength of beams and inner- and outer-scale of turbulence on scintillation are analyzed numerically. Compar- ison between the scintillation of GSM beams under the von Karman spectrum and that of beams under the modified Hill spectrum is made. The results obtained show that the scintillation index obtained under the von Karman spectrum is smaller than that under the modified Hill spectrum. This study can find theory bases for the experiments of the partially coherent GSM beam propagation through atmospheric turbulence.

关键词： atmospheric turbulence partially coherent beam scintillation atmospheric propagation

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Influence of moderate-to-strong anisotropic non-Kolmogorov turbulence on intensity fluctuations of a Gaussian–Schell model beam in marine atmosphere

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Chinese Physics B 2018年第5期27卷 220-226页

作者：程明建郭立新李江挺 School of Physics and Optoelectronic Engineering Xidian University Xi'an 710071 China State Key Laboratory of Pulsed Power Laser Technology Hefei 230037 China

The scintillation index（SI） of a Gaussian–Schell model（GSM） beam in a moderate-to-strong anisotropic nonKolmogorov turbulent atmosphere is developed based on the extended Rytov theory. The on-axis SI in a marine atmosphere is higher than that in a terrestrial atmosphere, but the off-axis SI exhibits the opposite trend. The on-axis SI first increases and then begins to decrease and saturate as the turbulence strength increases. Turbulence inner and outer scales have different effects on the on-axis SI in different turbulent fluctuation regions. The anisotropy characteristic of atmospheric turbulence leads to the decline in the on-axis SI, and the rise in the off-axis SI. The on-axis SI can be lowered by increasing the anisotropy of turbulence, wavelength, and source partial coherence before entering the saturation attenuation region. The developed model may be useful for evaluating ship-to-ship/shore free-space optical communication system performance.

关键词： atmospheric turbulence Gaussian-Schell model beam scintillation atmospheric propagation

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Influence of dynamic parameters on interacting efficiency between ground-based laser and air-based flying target

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Chinese Optics Letters 2014年第A2期12卷 1-7页

作者：邓少永张世强孙艳宏关小伟 Northwest Institute of Nuclear Technology Xian710024 China

We simulate the integrated effects of atmospheric aberration, atmospheric turbulence, thermal blooming, random jitter of laser＇s intensity and phase, speed of wind, direction of wind, absorption of air, kinetic cooling of CO2 and N2, speed of target, output power and beam quality of laser, wavelength, focus length, and the launch altitude of laser to accurately simulate the transmission loss of the laser＇s energy, concentration of laser＇s power and other beam quality parameters of the laser propagating to the dynamic target. And we evaluate the efficiency of laser＇s irradiation on the target more accurately for the optical link of ground-toairspace. We also investigate influences of characteristics of dynamic parameters （Strehl＇s ratio, RMS of wavefront, spatial distribution of intensity on the target, the real focus on the optical link and the peak intensity along the propagation path） including speed of wind, direction of wind, speed of target and the kinetic cooling effect of air, especially. We conclude that the higher speed of wind and target weakens the thermal blooming of atmosphere and improves the beam quality and efficiency of laser＇s irradiation on the target. The kinetic cooling effect of air is more remarkable to improve the beam quality irradiating on the target at the initial part of the propagation path of the laser. The changed direction of wind weakens the atmospheric aberration and directs to better beam quality and higher efficiency of laser＇s irradiation on the target.

关键词： 010.1290 atmospheric optics 010.1300 atmospheric propagation 010.1330 atmospheric turbulence

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Performance of free-space optical communication systems using circle polarization shift keying with spatial diversity receivers

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Chinese Optics Letters 2013年第14期11卷 1-4页

作者：刘超姚勇杨彦甫袁易君赵宇峰于本双 Department of Electronic and Information Engineering Shenzhen Graduate School Harbin Institute of Technology Shenzhen 518055 China

A closed-form bit-error rate （BER） expression is derived for free-space optical （FSO） communication systems with circle polarization shift keying and spatial diversity receivers in the gamma-gamma （GG） distribution fading channel. This model can predict the performance without the need of lengthy simulation runs. The performance can be analyzed by some system parameters such as atmospheric conditions, link length, communication wavelength, receiver aperture size, and number of spatial diversity receivers. Numerical results demonstrate the influence of the above parameters on the FSO systems and show quantitatively the differences in behavior among various different parameters.

关键词： 010.1300 atmospheric propagation 010.1330 atmospheric turbulence 060.2605 Free-space optical communication 060.4080 Modulation

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