[1] [1] McCumber D E. Einstein relations connecting broadband emission and absorption spectra. Phys. Rev., 1964, 136(4A):A954～A957

[2] [2] Miniscalw W J, Quimby R S. General procedure for the analysis of Er3+ cross sections. Opt. Lett., 1991, 16(4):258～260

[3] [3] Payne S A, Chase L L, Smith L K et al.. Infrared crosssection measurements for crystals doped with Er3+, Tm3+, and Ho3+. IEEE J. Quant. Electron., 1992,QE-28(11):2619～2630

[4] [4] Payne SA, Caird J A, Chase L L et al.. Spectroscopy and gain measurements of Nd3+ in SrF2 and other fluoride-structure hosts. J. Opt. Soc. Am. (B), 1991, 8(4):726～741

[5] [5] Martin W E, Milam D. Gain saturation in Nd:doped laser materials. IEEEJ. Quant. Electron., 1982, QE-18(7):1155～1163

[6] [6] Payne S A, Chase L L, Newkirk H W et al.. LiCaAlF6:Cr3+:a promising new solid-state laser material. IEEE J. Quant. Electron., 1988, QE-24(11):2243～2251

[7] [7] Sumida D S, Fan T Y. Effect of radiation trapping of fluorescence lifetime and emission cross section measurements in solid-state laser media. Opt. Lett.,1994, 19(17):1343～1345

[8] [8] McCumber D E. Theory of photon-terminated optical masers. Phys. Rev., 1964, 134(2A):A299～A306

[9] [9] Judd B R. Optical absorption intensities of rare earth ions. Phys. Rev., 1962, 127(3):750～761

[10] [10] Ofelt G S. Intensities of crystal spectra of rare-earth ions. J. Chem. Phys., 1962, 37(2):511～520

[11] [11] Sanz J. Casez R, Alcala R. Optical properties of Tm3+ in fluorizirconate glass. J. Non-Cryst. Solids, 1987, 93(2/3):377～386

[12] [12] Taninura K, Shinn M D, Sibley W A. Optical transitions of Ho3+ ions in fluorizirconate glass. Phys. Rev. (B), 1984, 30(5):2429～2437

[13] [13] Zou X, Toratani H. Spectroscopic propeties and energy transfers in Tm3+ single- and Tm3+/Ho3+ doubly-doped glasses. J. Non-Cryst. Solids, 1996, 195(2):113～124

[14] [14] Allain J Y, Monerie M, Poignant H. Ytterbium-doped fluoride fibre laser operating at 1.02 μm. Electron. Lett., 1992, 28(11):988～989

[15] [15] Shinn M D, Sibey W A, Drexhage M G et al.. Optical transitions of Er3+ ions in fluorizirconate glass. Phys. Rev. (B), 1983, 27(11):6635～6648

[16] [16] Seeber W, Downing E A, Hesselink L et al.. Pr3+-doped fluoride glasses. J. Non-Cryst. Solids, 1995, 189(3):218～226