Design and realization of long-period grating devices in conventional and high birefringence fibers and their novel applications as fiber-optic load sensors

We report the design and fabrication of long-period fiber gratings with single and cascaded structures in conventional and high birefringence (hi-bi) fibers using amplitude mask and point-by-point writing techniques. We also report a novel application of long-period gratings produced in nonhigh-birefringence fiber as fiber-optic load sensors exhibiting very high transverse strain sensitivity. Sensitivity some 800 times greater than previously reported fiber Bragg grating (FBG) sensors has been achieved.