Dynamitic Cascaded FBG based filter used in DWDM networks

摘要

The characteristics of uniform fiber Bragg gratings (FBGs) is analyzed. The reflected spectra in apodized uniformly periodic FBGs are calculated and the double exposure technique is used in suppressing the sidelobes of uniform gratings. After that, the corresponding FBGs filters used in DWDM networks and systems are imprinted. Based on the apodized FBGs, a cascaded FBGs filter module is proposed, in which two, or more, pieces of identical FBGs, with the same central wavelength, same bandwidth and same reflectivity, are spliced in series and each FBG is equipped with tuning device. By controlling the tuning device, the module can act either as a tunable single channel filter with its central wavelength and/or bandwidth being tunable, or as a double channel filter with its central wavelength being tunable. The tested results demonstrated that the module can dynamically tuned in the range of several nanometers.