Fabrication of temperature-insensitive chirped fiber grating pressure sensor

Based on the transfer matrix method, the reflection spectra of strained chirped fiber gratings are analyzed theoretically. Chirped fiber gratings are fabricated by etching uniform FBGs with HE The cross section of the chirped FBG has a gradient variation along the axis. The full width at half maximum of the refection spectra of the chirped fiber grating can reach 0.4-0.75nm. When axial stress is applied on the chirped FBG, the bandwidth can reach 5nm. The sensitivity of the bandwidth to stress can achieved 20% higher than that of uniform fiber Bragg gratings. The relationship of the bandwidth and the imposed force, as well as the one between the reflection power and the force, derived from the coupled mode theory, will also be tested in the experiments, which has been shown in this paper.