Embodiments of present invention provide a digital dispersion compensation module. The digital dispersion compensation module includes a multi-port optical circulator; and a plurality of dispersion compensation units connected to the multi-port optical circulator, wherein at least one of the plurality of dispersion compensation units includes a fiber-bragg grating (FBG) having a first port and a second port; and an optical switch being capable of selectively connecting to one of the first port and the second port of the FBG, wherein the at least one of the plurality of dispersion compensation units is adapted to provide a positive dispersion to an optical signal, from the multi-port optical circulator, when the optical switch connects to the first port of the FBG and is adapted to provide a negative dispersion to the optical signal when the optical switch connects to the second port of the FBG.