Fiber Bragg grating location by a side-scatter technique based on cladding-mode coupling.
At wavelengths slightly shorter than the normal resonance for a fiber Bragg grating, radiation can be coupled into cladding and radiation modes that become visible external to the fiber. We describe experimental measurements on a fiber Bragg grating under broadband illumination, showing the axial variation and angular distribution of side-scattered radiation. The scattering signal can locate the grating position subject to an offset in the backscatter direction. The spectrum of scattered radiation is consistent with a published theoretical model of mode coupling by a grating in a finite cladding fiber.
Maier
Robert R
RR
School of Engineering and Physical Science, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom. r.r.j.maier@hw.ac.uk
Barton
James S
JS
Jones
Julian D
JD