电子辐照对掺铒单模光纤损耗特性的影响

EFFECTS OF ELECTRON IRRADIATION ON LOSS CHARACTERISTICS OF SINGLE MODE OPTICAL FIBERS DOPED WITH RARE EARTH Er^(3+)

本文介绍了掺铒(Er^(3+))单模光纤电子辐照特性,测量了辐照前后和退火后的光纤参数。发现在0.80-1.60μm范围内辐照引起的损耗很大,在0.80-1.20μm短波部分辐照损耗遵循Luv=0.342exp[E/0.166];而1.20-1.60μm长波部分遵循L_(IR)=2.2·10~4exp[-6.08E](E的单位为eV)。120℃退火60h可使长波辐照损耗减少,但0.80μm附近的损耗反而增加。最后讨论了辐照损耗的机理,估计出辐照引起氧和硅原子的位移几率分别为7.1×10^(-8)和3.9×10^(-8)。在1.40μm处位移原子引起的损耗比相同数量的OH^-引起的损耗要大200倍之多。退火能使部分位移原子复原,使损耗有所恢复。

This paper presents the effects of electron irradiation on the characteristics of single mode optical fibers doped with rare earth Er3+. The parameters of optical fibers are measured, prior to irradiation and after irradiation and annealing. It has been found that absorption loss in the wave length range of 0.80-1.60 μm is greatly lager than those of unirradiationed fibers. The irradiation induced loss obeys the following exponential laws: L_(uv) =0.342exp [E(eV)/0.166] in the range of 0.80-1.20 urn and LIR = 2.2×104exp [-6.08E(eV)] in the range of 1.20-1.60 μm range. During annealing, the induced loss at longer wave length decreases, but that near 0.80 μm increases. Finally, the paper discusses the mechanism of loss variations. The displaced probability of oxygen and silicon atoms in electron irradiation is estimated to be 7.1×10^(-3) and 3.9×l0^(-3), respectively. The loss induced by displaced atoms is 200 times langer than that induced by the same amount of OH^- at 1.40 μm. The process of annealing of the loss essentially occurs in two steps, i.e., by neutralization of the free electron and reforming of the broken bonds.