Long-range propagation through inhomogeneous turbulent atmosphere: analysis beyond phase screens (original) (raw)
Related papers
2010
Laser beam propagation in maritime environment is particularly challenging, not only for scattering and absorption due to high humidity, but also for a different behavior of atmospheric turbulence with respect to terrestrial propagation. Recently, a new power spectrum for the fluctuations of the refractive index in the Earth's atmosphere has been introduced to describe maritime atmospheric turbulence. This maritime power spectral model shows a characteristic bump, similar to Hill's bump, that appears when the product between the wavenumber and the inner scale is around unity, 0 1 l N. In this paper, under weak turbulence conditions, we use the mentioned maritime power spectrum to analyze long term beam spread, beam wander and Strehl ratio of a Gaussian beam wave propagating through maritime atmospheric turbulence.
Effects of light propagation in middle intensity atmospheric turbulence
Frontiers of Optoelectronics in China, 2009
The purpose of this report is to present an experimental study of the effects of light propagation through atmospheric turbulence. Free space optical communication is a line-of-sight technology that transmits a modulated beam of visible light through the atmosphere for broadband communication. The fundamental limitations of free space optical communications arise from the environment through which it propagates. However these systems are vulnerable to atmospheric turbulence, such as attenuation and scintillation. Scintillation is due to the air index variation under the temperature effects. These factors cause an attenuated receiver signal and lead to higher bit error rate (BER). An experiment of laser propagation was carried out to characterize the light intensity through turbulent air in the laboratory environment. The experimental results agree with the calculation based on Rytov for the case of weak to intermediate turbulence. Also, we show the characteristics of irradiance scintillation, intensity distribution and atmospheric turbulence strength. By means of laboratory simulated turbulence, the turbulence box is constructed with the following measurements: 0.5 m wide, 2 m long and 0.5 m high. The simulation box consists of three electric heaters and is well described for understanding the experimental set up. The fans and heaters are used to increase the homogeneity of turbulence and to create different scintillation indices. The received intensity scintillation and atmosphere turbulence strength were obtained and the variation of refractive index, with its corresponding structure parameter, is calculated from the experimental results.
Wireless Optical Communications Through the Turbulent Atmosphere: A Review
Optical Communications Systems, 2012
Wireless Optical Communications Through the Turbulent Atmosphere: A Review 3 in the angle respect the optical axis at the receiver represent the concept of angle-of-arrival fluctuations. Furthermore, this bouncing of the optical wavefront as it propagates through the atmosphere is also responsible for the beam wander effect as the centroid of the laser beam is displaced randomly at the receiver plane.
Light propagation through anisotropic turbulence
Journal of the Optical Society of America A, 2011
A wealth of experimental data has shown that atmospheric turbulence can be anisotropic; in this case, a Kolmogorov spectrum does not describe well the atmospheric turbulence statistics. In this paper, we show a quantitative analysis of anisotropic turbulence by using a non-Kolmogorov power spectrum with an anisotropic coefficient. The spectrum we use does not include the inner and outer scales, it is valid only inside the inertial subrange, and it has a power-law slope that can be different from a Kolmogorov one. Using this power spectrum, in the weak turbulence condition, we analyze the impact of the power-law variations α on the long-term beam spread and scintillation index for several anisotropic coefficient values ς. We consider only horizontal propagation across the turbulence cells, assuming circular symmetry is maintained on the orthogonal plane to the propagation direction. We conclude that the anisotropic coefficient influences both the long-term beam spread and the scintillation index by the factor ς 2−α .
Free-Space Laser Communications X, 2010
Laser beam propagation in maritime environment is particularly challenging, not only for scattering and absorption due to high humidity, but also for a different behavior of atmospheric turbulence with respect to terrestrial propagation. Recently, a new power spectrum for the fluctuations of the refractive index in the Earth's atmosphere has been introduced to describe maritime atmospheric turbulence. This maritime power spectral model shows a characteristic bump, similar to Hill's bump, that appears when the product between the wavenumber and the inner scale is around unity, 0 1 l N. In this paper, under weak turbulence conditions, we use the mentioned maritime power spectrum to analyze long term beam spread, beam wander and Strehl ratio of a Gaussian beam wave propagating through maritime atmospheric turbulence.
Ten Years of Research on Light Propagation through a Turbulent Atmosphere
2008
A brief account of the studies about light propagation through a turbulent atmosphere in the XX Century will be presented. In this description the emphasis is made on the development of the ideas that permitted the interpretation of the complex processes observed in the Nature and experimented inside a laboratory and outdoors, as well as a description of the observational techniques employed. In 1996 theoretical and experimental research activity on light propagation through a turbulent atmosphere begun in La Plata, Argentina. A review of the experiments, the obtained results and the achieved interpretations, as well as some details of the prospective future activities, will be done.
Non-Kolmogorov atmospheric turbulence and optical signal propagation
Nonlinear Processes in Geophysics, 2006
In the present review, we make an attempt to attract attention to the effect of non-Kolmogorov behavior of turbulence in various scales on the characteristics of electromagnetic waves propagation through a turbulent atmosphere on the example of certain atmospheric experiments. We discuss the interpretation of experimental data based on the model of spectral behavior of a passive scalar field within a broad range of scales, which has been developed recently.
Light propagation through multilayer atmospheric turbulence
Optics Communications, 1997
A new treatment is presented for light propagation through multilayer turbulence. Equations for the intensity and phase of an observed wavefront are derived together with their validity conditions for both single and multiple layer systems. A method for finding the statistics of observed scintillations is presented together with a detailed calculation for a single layer system. 0 1997 Elsevier Science B.V.
The effects of atmospheric turbulence on the propagation of pulsed laser beams
Radio Science, 1975
The effects of turbulence on the propagation of pulsed laser beams are examined. Using the Rytov theory, general expressions for the pulse fluctuations are derived in terms of arbitrary beam geometries and pulse shapes. Physical interpretations of the pulse distortion and the effects of the beam geometry on the pulse statistics are discussed.
Optical Engineering, 2014
Optical beam spread and beam quality factor in the presence of both an initial quartic phase aberration and atmospheric turbulence are studied. We obtain the analytical expressions for both beam radius-squared and the beam quality factor using the moment method, and we compare these expressions with the results from Monte Carlo simulations, which allow us to mutually validate the theory and the Monte Carlo simulation codes. We then analyze the first-and second-order statistical moments of the fluctuating intensity of a propagating laser beam and the probability density function versus intensity as the beam propagates through a turbulent atmosphere with constant C 2 n. At the end, we compare our analytical expression and our simulations with field test experimental results, and we find a good agreement.