Novel Fabrication of Ultra-Strong Thermally Stable Gratings through the Coating of Optical Fibers with UV Light

Abstract : We optimize the properties and fabrication process of fiber Bragg gratings for sensors and for stabilization of semiconductor lasers. We investigate the effects of boron and titanium doping on thermal sensitivity. We find that gratings written through the polymer coating are stable to high-intensity infrared light traveling in the core of the fiber. These gratings are designed for wavelength locking of semiconductor lasers used for pumping erbium-doped fiber amplifiers. We find that hydrogen-loaded fibers have reduced mechanical strength compared to fiber gratings written without hydrogen. We also investigate the effect of thermal annealing on the strength of fiber gratings. We find that annealing at 230 degrees C slightly improves the fiber's mechanical strength, while annealing hydrogen-loaded fibers decreases the fiber's mechanical strength. Bending sensitivity of gratings is measured.