Bending and orientational characteristics of long period gratings written in D-shaped optical fiber

Allsop, Thomas D.P.; Gillooly, Andrew M.; Mezentsev, Vladimir; Earthgrowl-Gould, T.; Neal, Ron; Webb, David J. and Bennion, Ian (2004). Bending and orientational characteristics of long period gratings written in D-shaped optical fiber. IEEE transactions on instrumentation and measurement, 53 (1), pp. 130-135.


Long period gratings (LPGs) were written into a D-shaped single-mode fiber. These LPGs were subjected to a range of curvatures, and it was found that as curvature increased, there was increasingly strong coupling to certain higher order cladding modes without the usual splitting of the LPGs stopbands. A bend-induced stopband yielded a spectral sensitivity of 12.55 nm·m for curvature and 2.2×10-2 nm°C-1 for temperature. It was also found that the wavelength separation between adjacent bend-induced stopbands varied linearly as a function of curvature. Blue and red wavelength shifts of the stopbands were observed as the sensor was rotated around a fixed axis for a given curvature; thus, in principle, this sensor could be used to obtain bending and orientational information. The behavior of the stopbands was successfully modeled using a finite element approach.

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Uncontrolled Keywords: bending, coupled mode analysis, diffraction gratings, fibre optic sensors, finite element analysis, position measurement, spectral line shift, surement, D-shaped single-mode optical fiber, FEM, curvature measurement, bend sensors, bend-induced stopband spectral sensitivity, bend-induced stopbands, blue wavelength shift, fiber bending characteristics, fiber orientational characteristics, higher order cladding mode coupling, long period gratings, red shift, sensor rotation, stopband wavelength separation, temperature measurement
Published Date: 2004-02



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