Laser communication link performance in free space depends heavily on atmospheric conditions present on the propagation path. Distortions due to atmospheric turbulence, such as scintillation and beam wander, greatly diminish signal detection and performance. With the final goal of improving the communication link, experimental measurements and analysis of turbulence strength are presented as metrics for determining the system’s detection limits. Experimental optical trials were recorded over a 1-km horizontal path in order to study the intensity fluctuations, beam dance, and the spatial spectrum properties under different regimes. By taking into account wind speed and vibrations of the building where the measurements were carried on, correlations between variables are shown with the use of a photodetector, and a 2D lateral effect position sensor.
We present a new analysis of laser propagation experiments carried out with the Laser Propagation Testbed (LPT) developed by TNO. A major goal of these experiments is to validate and improve atmospheric propagation models that are essential to applications such as laser communication, high energy laser weapon systems and remote sensing. The data were obtained during a field campaign with a 1W 1556 nm laser beam deployed over a 3.6 km maritime path in The Netherlands. The measurements consist of intensity profiles of the propagated laser beam and local meteorological and atmospheric conditions (visibility, refractive index structure parameter and aerosol data) obtained during a ten day period under varying weather conditions. We use the locally measured atmospheric conditions and numerical weather prediction to constrain a turbulent laser propagation model developed by TNO, and compare the results with the time series measurements of the laser beam profile.
In order to improve laser communication link performance, turbulence strength is an important parameter to characterize the system’s correcting limits and detection availability. By setting an experimental optical link through free space horizontal propagation in a 1-km path, we study the strength of different turbulence scenarios through the Rytov approximation and scintillation of the beam, and compare methods of experimental detection of the refractive-index structure constant of the turbulence, C2n . Results show that, under low and medium turbulence regimes, both methods behave similiarly as a way to predict C2n ; however, with larger turbulence strength, the beam’s displacements in the focal plane are more sensitive than the intensity fluctuactions.
Conference Committee Involvement (1)
Environmental Effects on Light Propagation and Adaptive Systems VII
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