Document Type : Research Paper


1 Department of Physics, College of Education, University of Al-Mustansiriyah - Iraq

2 Laser & Optoelectronic Research Center, Ministry of Science & Technology - Iraq


Free-space laser communication systems usually experience strong channel fading caused by atmospheric turbulence. To mitigate the impact of atmospheric turbulence on free-space optical links using compensation techniques including adaptive optical (AO) system as advanced technique. Its three main components have remained constant: a wave front sensor to measure distortion, a wave front corrector to compensate for the distortion and a control system to calculate the required correction and necessary shape to apply to the corrector. Optical communication schemes utilizing adaptive optical at the transmitter are proposed. Numerical simulations show that the proposed schemes can significantly reduce the channel fading. The main goal of any adaptive optical system is to show a phase correction in the arriving wave front that converts the distorted wave front into a plane wave. A free space optical AO system to mitigate turbulence-induced phase fluctuations has been implemented by using a wavefront sensorless architecture The AO system was designed to correct the first 20 Zernike modes by using two separated active mirrors: a tip/tilt corrector and a DM with 32 actuators. Also, standard deviation of the atmospheric tilt was computed, DM stroke, the residual phase variance, the turbulence strength for different telescope apertures.


Main Subjects

[1] L.C. Andrews, R.L. Philips, “Laser beam
propagation through random media,” Bellingham,
SPIE Press, 2005.
[2] R.K. Tyson: “Introduction to Adaptive Optics,”
Bellingham, SPIE Press, 2000.
[3] Sh.A. Kadhim, A.H. Dagher, J.A. Khlati,
“Characterization study of (FSO-RF) Hybrid
communication link,” 2014.
[4] R. Tyson:"Principles of adaptive optics", CRC
Press, 3rd edition, 2011.
[5] E. Anzuola, A. Belmonte, “Adaptative
compensation on free-space optical coherent systems,”
Technical University of Catalonia, Department of
Signal Theory and Communications, 08034 Barcelona,
[6] H.W. Babcock, “The possibility of compensating
astronomical seeing,” Publications of the
Astronomical Society of the Pacific, 229–236, 1953.
[7] E.A. Valencia, “Atmospheric Compensation
Experiments On Free-Space Optical Coherent
Communication Systems,” 2015.
[8] T. Weyrauch, M. Vorontsov, “Free-space laser
communications with adaptive opticsatmospheric
compensation experiments,” J. Opt. Fiber Comms.
Rep. 1, 355-379, 2004.
[9] A.A.B. Raj, J.A.V. Selvi, and S. Raghavan,
“Terrestrial free space line of sight optical
communication (tfslsoc) using adaptive control
steering system with laser beam tracking, aligning and
positioning (atp),” in [Wireless Communication and
Sensor Computing, 2010. ICWCSC 2010.
International Conference on], 1–5, 2010.
[10] R. Conan and C. Correia, “Object-oriented matlab
adaptive optics toolbox,” 2014.
[11] R. Conan, [Object-Oriented Matlab Adaptive
Optics. User Guide] 2013.
[12] A. Glindemann, [Principles of Stellar
Interferometry], Springer 2011.