Investigation of the Effects of Macro Bending Loss on Step index Single Mode Fiber
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Date
2012-06
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Addis Ababa University
Abstract
The objective of the thesis are to calculate power loss due to bending, to determine
the spectral window at which ber can e ectively operates, to predict bend loss for a
higher wavelength from the trend of shorter wavelengths and investigates the variation
constants of optical ber (MAC) factor,with respect to using Laser stage lighting, He-Ne
laser and Diode laser, with wavelengths in the visible and infra red region of an optical
spectrum.
In this thesis, a single mode ber (SMF) was bent to various bend radius with a spe-
cially designed, adjustable ber bending device and out put power was measured using
a lock in ampli er. Thus, studying the relationship between macro bending and atten-
uation would enable us to maximize the performance of an optical ber. As a whole in
my experimental investigation was made of the bending losses in step index single mode
ber wave guide with di erent parameters of the equivalent step pro le for bending radii
from 0.5cm to 10.05cm with steps of 0.5cm, with the attenuation coe cient range is 0.045
dB/m to 0.475 dB/m,0.065 dB/m to 0.48 dB/m and 0.10 dB/m to 0.61 dB/m for the
wavelengths 532nm, 633nm and 808nm respectively
As signal wavelength passes the cut o wavelength, attenuation decreases sharply due
to disappearance of higher order mode. At wavelengths longer than cut o wavelength,
attenuation increases with wavelength increases. Furthermore, attenuation is inversely
proportional to bending radius measured at transmission wavelengths increases.
This study shows that attenuation introduced by macro bending depends on wave-
length and bending radius. Based on these ndings, one can minimize the adverse impact
of macro bending. As a whole the results from the experiment have suggested that the
optical power loss due to bending at the visible spectrum is more apparent than loss due
to other e ects such as absorption and scattering
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Acronyms
a.u.................................. Arbitrary Unit
FTTH ................................Fiber-to-the-Home
IR .. ..................................Infra red
ITU-T ................................International Telecommunication Union-Testing
LASER ...............................Light Ampli cation Stimulated by Emission of Radiation
MDUs ................................Multiple-Dwelling Units
MFD ...............................Mode Field Diameter
NA ...............................Numerical Aperture
ppm ...............................parts per million
SMF ...............................Single Mode Fiber
SFUs ................................Single-Family Units
UV ................................Ultra Violet
Key words: macro bending ; optic beam launch; optical spectrum; radius of curvature:
Single mode ber: spectral window; power loss
Description
Keywords
Macro Bending, Optic Beam Launch, Optical Spectrum, Radius Of Curvature, Single Mode Fiber, Spectral Window, Power Loss