8Nusinsky I, Hardy A A. Analysis of the effect of upconversion on signal amplification in erbium-doped fiber amplifiers (EDFA)[J].IEEE Journal of Quantum Electronics, 2003, 39(4):548-554.
9Philipsen J L, Broeng J, Bjarklev A, et al. Observation of strongly nonquadratic homogeneous upconversion in Er-doped silica fibers and reevaluation of the degree of clustering[J]. IEEE Journal of Quantum Electronics,1999,35(11):1741-1749.
10Fu L B, Tan G, Xu W J, et al. Ultraviolet-initiated reactions of H2 with germanosilicate fibers and H concentration dependence of the bragg wavelength of a fiber grating[J]. Optics Letters, 2000,25(8): 527-529.
