Tunable chirped fiber grating based gain flattening filter

In the proposed grating tuning structure, the Bragg fiber grating is tuned by applying mechanical stress through a supported beam. The tuning structure is constructed using polymethyl methacrylate. Through this tuning structure, the shape and center transmission wavelength of the chirped grating can be adjusted independently. This enables flexible adjustment of the filter spectrum for the purpose of dynamic gain flattening.