University of California, Riverside

Department of Electrical and Computer Engineering



Effects of the Atmospheric Channel on Free-space Laser Communications


Effects of the Atmospheric Channel on Free-space Laser Communications
 
Arun Majumdar
Department of Electrical Engineering, University of California at Los Angeles

Date: Monday, January 22, 2007
Time: 11:00am
Location: Bourns A265

In this talk I will present an overview of how the presence of atmospheric turbulence and scattering/absorbing media in the atmospheric channel degrade high-data-rate free-space laser communication performance. Fog, rain, dust, snow, smoke, molecular absorption, and aerosol particulate matter all attenuate the signal-carrying laser beam, and to a certain extent can be compensated for by increasing the signal gain or by appropriate selection of the optical wavelength. In contrast, random fluctuations in the atmosphere’s refractive index severely degrade the wave-front quality of a signal-carrying laser beam, causing intensity fading and random signal losses at the receiver.  Recent results on atmospheric turbulence measurements over desert site using ground-based instruments, kite/tethered-blimp platform and aircraft relevant to optical communications will be presented. For many cases of practical interest, the limiting factor in robust free-space optical communication link performance can be the presence of clear-air atmospheric turbulence in the optical channel. Results from numerical simulations are presented for analyzing communications performance for various scenarios: Downlink, Uplink and Terrestrial (Horizontal) link.

I will also point out the state-of-the-art research and development and future direction in this exciting area of free-space laser communications in government, commercial (lasercom and aerospace industries) and university organizations. 

About the speaker:


Dr. Majumdar has demonstrated leadership skills in Research and Development for the last 25 years from Industry, University and National Laboratory settings in the areas of atmospheric turbulence effects on free-space laser communications, propagation and imaging. He has a Ph.D. in Electrical Engineering from the University of California at Irvine, and an M.S. in Electrical Engineering from the University of Texas at Austin.

His research work at LCResearch, Inc. (his own company) involves the recent projects from The Boeing Company and DARPA/Schafer Corporation.  His previous significant professional experience includes: five years as a Full Professor in the Electrical Engineering and Computer Science department of the University of Colorado (Teaching/Research); three years as Senior Research Scientist at Particle Measuring Systems, Inc. in Boulder, Colorado; five years as Senior Research Scientist at Lockheed-California Company; four years as a Visiting Professor at NIST in Boulder, Colorado; four years as a Senior Scientist at Caltech’s Jet Propulsion Laboratory in Pasadena, California; Staff Member at MIT Lincoln Laboratory; and Summer Research Assistant at Harvard University, Gordon McKay Laboratory (Antenna Study).
Summary of Professional Achievements include:
-  Edited and Wrote a book “Free-Space Laser Communications: Principles and Advances” to be published by
Springer-Verlag, New York, NY, to be published in 2007. (Co-editor: Dr. Jennifer Ricklin)
-  Elected as Editorial Board Member of the new journal, JOFCR (Journal of Optical and Fiber Communications
Reports), Springer, New York, 2006.
-  Elected Chairman for organizing the International Conference on Free-Space Laser Communications, 2007:
-  Offered Professional Short Course on “Fundamentals of Free-Space Laser Communications,” at Industries
(The Boeing Company, BAE Systems) and at various SPIE conferences 
-   Editor of recent Proceedings:  Free-Space Laser Communications VI, SPIE Vol. 6304 (2006)
-  Demonstrated record of research accomplishment, including the publication of over fifty refereed journal and
conference papers and technical reports. Current reviewer for IEEE, OSA, SPIE, Springer and Elsevier journals.
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Electrical and Computer Engineering
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University of California, Riverside
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