BY modifying phase mask UV exposure system and inserting a circumvolved device which making optical fiber rotation in back of the phase mask, the PMD in fiber Bragg gratings (FBGs) is compensated. The average differential group delays (DGD) are 18 2 ps and 0.2 ps before and after compensation, respectively. These have already be used to 40 Gb/s OTDM system as dispersion compensators, and polarization mode dispersion (PMD) in 122 km G.652 SMF was successfully compensated by two chirped FBGs in a 40Gb/s OTDM transmission system.