Ytterbium-doped silica fiber (YDF) has important applications in space laser communication, space trash disposal, and even space laser weapon. However, the performance degradation introduced by space particle irradiation seriously restricts the space application of YDF.
In a recent study, a team from Shanghai Institute of Optics and Fine Mechanics of the Chinese Academy of Sciences, has made new progress on radiation resistant YDF. Related work was published on Optical Materials Express
In their experiment, the YDF preform was cut into two sections. One session underwent loading gas, pre-irradiation and thermal annealing pretreatment in turn (named pretreated), and the other one, without any pretreatment, was used as a reference (named pristine). Following this process, two optical fibers were drawn from pristine and pretreated preforms, respectively.
Laser experiments showed that this new pretreatment method had no obvious negative impact on the optical loss at 1200 nm (6 vs. 20 dB/km) and laser slope efficiency (79% vs. 75%) of non-irradiated YDFs.
Furthermore, they found that after an irradiation dose level of 700 Gy, the degradation of laser output power in pretreated YDF remained below 21% (from 79% to 59%), whereas the pristine YDF had no laser output at all, which meant this method could significantly improve the radiation resistance of YDF.
Vacuum experiment on the pretreated YDF predicts that the pretreated YDF may have a long-term radiation resistance stability when it is used in a vacuum environment (such as space).
The research was supported by the National Natural Science Foundation of China (NSFC).
Fig.1. Optical loss spectra and laser slope efficiency (Image by SIOM)