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Proceedings Paper

Investigation of near and mid infrared (1.34, 1.55 and 8.1&mgr;m) laser propagation through the New York City metro area
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Paper Abstract

Low power Mid-IR laser light exhibits much lower attenuation in propagation through the New York metro area when compared to Near-IR wavelengths. Depending on the type of atmospheric extinction we record a reduction of up to 800% in the exponential Beer-Lambert coefficient for Mid-IR light compared to Near-IR, thereby demonstrating the possibility of significantly increased deployable range and SNR of current communication systems by utilizing the Mid-IR spectrum. We present and analyze transmission data from an outdoor collinear, coaxial, multi-wavelength laser test bed comparing 1.31&mgr;m, 1.55&mgr;m and 8&mgr;m through outdoor atmospheric fog and rain over a 550 m free space optical link across the Stevens Institute of Technology campus. This is achieved using lasers with average power ranging from 1 mW (Mid-IR QCL) to tens of milliwatts which have been normalized under lock-in detection. We also present corroborating results from an indoor fog experiment simulating various fog types. Here we have also deconstructed Beer's attenuation coefficient and distinguish the contribution of scattering and absorption with a purpose-built polar nephelometer. Using Mie predictions we determine and measure the extent by which a Mid-IR system scatters light less under fog than a traditional Near-IR one, hence accounting for the performance enhancement in the metro-air test bed. We conclude finally that the Kruse-Mie prediction of insignificant Mid-IR-over-Near-IR-gain is strongly in error.

Paper Details

Date Published: 4 May 2007
PDF: 12 pages
Proc. SPIE 6551, Atmospheric Propagation IV, 655107 (4 May 2007); doi: 10.1117/12.720015
Show Author Affiliations
Paul Corrigan, Stevens Institute of Technology (United States)
Rainer Martini, Stevens Institute of Technology (United States)
Edward Whittaker, Stevens Institute of Technology (United States)
Claire Gmachl, Princeton Univ. (United States)

Published in SPIE Proceedings Vol. 6551:
Atmospheric Propagation IV
Cynthia Y. Young; G. Charmaine Gilbreath, Editor(s)

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