Efficient Fiber Gratings Formed on High NA Dispersion-Shifted Fiber and Dispersion-Flattened Fiber

Abstract
A wavelength separation as wide as 7 nm has been achieved between the Bragg wavelength and the onset wavelength of radiation mode coupling in highly reflective fiber gratings by using a high NA dispersion-shifted fiber (DSF) and a dispersion-flattened fiber (DFF). We have used this technique to fabricate highly reflective chirped gratings with a bandwidth of 8 nm. These types of fibers are also suitable for fabricating highly reflective multi-wavelength filters.