By optimizing the fabrication process of the chirped optical fiber Bragg grating (FBG), some key problems of FBG are solved, such as the temperature stabili ty, time delay ripple coefficient, bandwidth, compensation of polarization mod e dispersion (PMD), and so on. The FBG we fabricated can attain the temperature coefficient less than 00005 nm/℃, its bandwidth is bigger than 14nm, tim e delay ripple is less than 50 ps, and the dispersion is higher than -1000ps/n m. The average PMD of the FBG dispersion compensator is measured by the Jones ma trix eigenvalue method, and is compensated. Its PMD is improved from 91406 ps to 01521 ps. With dispersion compensation by two wide_band FBGs we fabricated, we have implemented a 40 Gb/s 122 km conventional single_mode optical fiber (G6 52) systems, with a power penalty being only 14 dB.