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Proceedings Paper

Effects of laser multimode content on the angle-of-arrival fluctuations in free-space optical access systems
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Paper Abstract

The effects of the multimode content in a laser beam on the angle-of-arrival fluctuations are examined for free space optics (FSO) access systems. Multimode excitation is represented by coherent addition of Hermite-Gaussian higher order modes. Root mean square angle-of-arrival fluctuations are formulated using the previously reported multimode phase structure function, which is valid in weak atmospheric turbulence. Results are found for practical FSO links operating at 1550 nm and 850 nm wavelengths and for link spans of up to 5 km. In choosing the mode content, various sequential grouping of all possible mode combinations are used up to a certain order (n,m) mode. We start with the single fundamental mode (TEM00) and span up to the highest order (n =10, m =10) mode. In this manner, different degrees of source coherence are also taken into account. Angle-of-arrival fluctuations are found to be in the range of several tens of μradians and almost insensitive to the mode content except for the cases when the mode group terminates with an odd mode. In such instances, the fluctuations rise to a few hundreds of μrad. Comparing our results with the field of view of a practical FSO receiver, which is several mrad, we conclude that the-angle-of arrival fluctuations due to multimode excitation will not influence the FSO link performance to a major extent.

Paper Details

Date Published: 25 May 2004
PDF: 7 pages
Proc. SPIE 5473, Noise in Communication, (25 May 2004); doi: 10.1117/12.546775
Show Author Affiliations
Halil Tanyer Eyyuboglu, Cankaya Univ. (Turkey)
Yahya Kemal Baykal, Cankaya Univ. (Turkey)

Published in SPIE Proceedings Vol. 5473:
Noise in Communication
Langford B. White, Editor(s)

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