Chirp tuning of a fiber Bragg grating by using different tapered transducers and loading procedures: an application in the accelerometer

A uniform period fiber Bragg grating can be chirped by applying an axially strain gradient. We have demonstrated a novel technique for making the chirped fiber Bragg gratings (CFBG), which involves bonding an unchirped fiber grating to the surface of a tapered stainless steel plate which is strained by loading. Three kinds of tapered profiles (convex, gradient and concave) of plates and two kinds of loading procedures (bending and dilating) were used as the means of an in situ absolute center wavelength shifting and reflection bandwidth broadening of a CFBG. By this method, the center wavelength of a CFBG could be tuned from 1548.92 nm to 1550.99 nm, and a maximum adjustable chirp bandwidth of 2.00 nm was obtained for a fiber Bragg grating in 50 mm length. An application in the accelerometer was introduced.