The radiation hardness method of ASE source based on the inhomogeneous photo-bleaching effect

• In this paper, the inhomogeneous photo-bleaching effect in erbium-doped fiber is firstly investigated. Due to the optical amplification and the absorption of color centers , the axial optical power distribution in EDF is inhomogeneous, so does the photo-bleaching process. By establishing the composite model of radiation-induced attenuation (RIA) and inhomogeneous photo-bleaching, the change of loss in EDF under radiation can be evaluated more accurately. • Based on the composite model, the main color centers in EDF are experimentally identified and the generation and bleaching parameters are determined. Main radiation-induced color centers in EDF include STH 2 , Al-OHC(1), and Al-OHC(4) color centers, in which the STH 2 and Al-OHC(4) color centers are unstable and can be partially bleached. • Based on the composite model, an active radiation hardening method of ASE source is proposed. By increasing the pump power of ASE source, the unstable color centers are annealed and the output power of ASE source is partially recovered, which is able to prolong the lifetime of the optoelectronic module (such as fiber optic gyroscope, erbium-doped fiber laser, etc.) under space radiation environment. Photo-bleaching can accelerate the bleaching speed of radiation-induced color centers in erbium-doped fiber (EDF), which is a promising radiation hardening method for amplified spontaneous emission (ASE) sources used for interferometric fiber optic gyroscopes (IFOGs). In existing research, the photo-bleaching process along the EDF is considered to be uniform distribution. However, we discovered that the axial optical power distribution in EDF is inhomogeneous, which makes the on-orbit performance prediction of ASE sources inaccurate. To address this issue, firstly, a composite model of radiation-induced attenuation and the inhomogeneous photo-bleaching process is established, and the power evolution in ASE sources under the radiation environment is extrapolated. Secondly, the numerical simulation and radiation experiment are executed to verify the inhomogeneity of the color centers in EDF. Finally, a radiation hardening method is presented by accelerating the photo-bleaching process of unstable color centers. The experiment result agrees well with the model prediction and reveals that the radiation hardening method can increase the lifetime of ASE sources by ∼ 30 %.