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Proceedings Paper

Interpretation of measured spectral attenuation curves of optical fibers by deconvolution with source spectrum
Author(s): Wolfgang Hoefle
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Paper Abstract

Nowadays spectral attenuation measurements on optical fibers are performed using high- precision, commercially available measurement equipment and the cut-back technique. Most instruments use a combination of halogen lamp and monochromator and operate with spectral widths of 5-10 nm. Since the spectral width of the absorption peaks of Si-O-H bonds in standard silica fibers is of the same order of magnitude, a significant error is introduced into these measurements. Simulations show considerable distortion of the measured data. Basically, the measured curve is a convolution of the true attenuation curve and the source spectral distribution. When measured curves are to be interpreted, the inverse problem, deconvolution of the respective curves, must be dealt with. The authors developed an algorithm to compute the true attenuation values from the measured data by numerically deconvoluting the measured curve with the source spectrum. It is show how the mathematical problem can be reduced to solving a system of linear equations. The algorithm is very unstable with respect to measurement errors, as a Monte-Carlo simulation shows. The necessary stability for practical purposes is achieved by fitting the data with a smooth function prior to the deconvolution. A procedure to deal with practical curves is derived: The measured data are first fitted with a special set of Gauss functions describing the OH-absorption peak at 1.4 micrometers . Then the numerical deconvolution is carried out with the source spectrum and the curve-fit performed earlier is repeated. By comparing the two fits and their parameter values, the influence of the spectral width is discussed.

Paper Details

Date Published: 1 September 1991
PDF: 7 pages
Proc. SPIE 1504, Fiber-Optic Metrology and Standards, (1 September 1991); doi: 10.1117/12.47000
Show Author Affiliations
Wolfgang Hoefle, Technische Univ. Braunschweig (Germany)

Published in SPIE Proceedings Vol. 1504:
Fiber-Optic Metrology and Standards
Oliverio D.D. Soares, Editor(s)

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