Linear and Gaussian Chirped Fiber Bragg Grating and Its Applications in Fiber-Optic Filtering and Sensing Systems

A novel technique for continuous chirp control of a fiber Bragg grating (FBG) based on a double-hole cantilever beam (DHCB) is proposed and experimentally demonstrated. The specifically designed DHCB provides a pressure-position-dependent strain-gradient along an originally uniform FBG and allows a tunable linear and Gaussian chirp modulation over the grating spectrum. Bandwidth and wavelength-independent tuning, under center-applied-pressure effect, is achieved by linear chirp modulation with a symmetrical broadening profile and a temperature-controlled wavelength shift. And intensity-referenced temperature-immune pressure measurement, under side-applied-pressure effect, is accomplished by Gaussian chirp modulation with a single-side-broadening profile and a linear-increasing reflection optical power.