bands of the corresponding radiation induced defect which can be diminished by a photo annealing light the photo annealing light source 100 which can be a laser or a broadband light source generates a light incident into the rare earth doped fiber of the optical fiber assembly 102 to reduce the ria preferably the wavelength of the photo annealing light is ranged from 355 nm to 980 nm and the ria at least from 900 nm to 1700 nm in wavelength can be efficiently recovered consequently the performance of the optical fiber assembly 102 could be recovered by the photo annealing light source 100 please refer to fig2 a which is a first preferred implementation case schematic diagram of the present invention showing a photo annealing light source 200 coupled to an optical fiber assembly 201 the optical fiber assembly 201 is used as a single pass backward configuration including a 3 port wdm 202 connected to an optical isolator 204 with an output port 205 a rare earth doped fiber 203 connected to the 3 port wdm 202 and a fiber termination 206 and a fiber splicing 207 preferably a rare earth doped fiber 203 is an edf erbium doped fiber the photo annealing light source 200 is also an optical pump light source for exciting the rare earth doped fiber 203 when a light from the photo annealing light source 200 is coupled to.