Tunable all-optical microwave filter using uniform fiber Bragg gratings with identical reflectivities

In this paper, we propose a novel approach to realizing all-optical microwave filtering using a broadband light source and fiber Bragg gratings (FBGs) with identical reflectivities. The filter tapping coefficients are determined by the spectrum profile of the broadband optical source. Since the FBGs have identical reflectivities, the characteristics of the FBGs with high uniformity is possible, which simplifies implementation and reduces implementation error. In addition, the spectrum profile of the broadband source can be controlled using an optical comb filter. Experiments are carried out and the results agree well with the theoretical analysis.