Schematic diagram of the partially etched FBG sensor under longitudinal strain. and denote radius and area of cross sections of nonetched grating (FBG-1) and etched grating (FBG-2) fiber, respectively.
Comparison of theoretical and experimental values of strain (in terms of wavelength shift) as a function of radius of the grating fiber. The inset is extended theoretical plot of strain as a function of radius of the fiber, .
Shift of two peaks under arbitrary tension. The peak for etched FBG-2 experiences approximately four times shift compared to nonetched FBG-1.
Plots (a) and (b) compare wavelength shift for FBG-1 with the shift in FBG-2 of diameter 61.75 and , respectively, as a function of strain.
Comparison between applied and measured strains by the proposed model. The half-filled circle points on solid lines are applied strain at different temperature. The empty circle point nearest to the half-filled circle point is the respective strain obtained from the model.
Strain measurement in terms of resultant wavelength shift of FBG-1 and FBG-2 at fixed temperature . in first and fifth rows are the induced strain corresponding to applied load .
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