Realization of chirped fibre Bragg gratings by using differently tapered transducers and loading procedures

A uniform period fibre Bragg grating (FBG) can be chirped by applying an ax ial strain gradient to it. We have demonstrated a novel technique for makin g chirped fibre Bragg gratings (CFBGs) which involves bonding a FBG to the surface of a tapered stainless steel plate that is strained by loading. Fou r kinds of tapered plate profiles (convex, gradient, concave and rectangula r) and two kinds of loading procedures (bending and direct tension) were us ed as the means for shifting the absolute centre wavelength in situ and bro adening the reflection bandwidth of a CFBG. With this method the centre wav elength of a CFBG was tuned from 1548.92 nm to 1550.99 nm, resulting in a m aximum adjustable change in bandwidth of 2.00 nm for a 5 cm long FBG.