Rodrguez V D, Tikhomirov V K, Mndez-Ramos J, et al. Towards broad range and highly efficient down-conversion of solar spectrum by Er3+-Yb3+ co-doped nano-structured glass-ceramics [J]. Sol. Energy Mater. Sol. Cells, 2010, 94:1612-1617. [2] Tick P A, Borrelli N F, Cornelius L K, et al. Transparent glass ceramics for 1 300 nm amplifier applications [J]. J. Appl. Phys., 1995, 78(11):6367-6374. [3] Wang Y, Ohwaki J. New transparent vitroceramics codoped with Er3+ and Yb3+ for efficient frequency upconversion [J]. Appl. Phys. Lett., 1993, 63(24):3268-3270. [4] Auzel F. Materials and devices with using double-pumped phosphon energy transfer [J]. Proc. IEEE, 1973, 61(6):758-786. [5] Vetrone F, Boyer J C, Capobianco J A, et al. Effect of Yb3+ codoping on the upconversion emission in nanocrystalline Y2O3[DK]：Er3+ [J]. J. Phys. Chem. B, 2003, 107(5):1107-1112. [6] Lu S Z, Yang Q H, Zhang B, et al. Upconversion and infrared luminescences in Er3+/Yb3+ codoped Y2O3 and (Y0.9La0.1)2O3 transparent ceramics [J]. Opt. Mater., 2011, 33(4):746-749. [7] Auzel F, Goldener P. Towards rare-earth clustering control in doped glasses [J]. Opt. Mater., 2001, 16(1):93-103. [8] Goldner P, Schaudel B, Prassas M, et al. Influence of the host structure and doping precursors on rare earth clustering in phosphate glasses analysed by co-operative luminescence [J]. J. Lumin., 2000, 87-89:688-690. [9] Meza O, Diaz-Torres L A, Salas P, et al. Color tunability of the upconversion emission in Er-Yb doped the wide band gap nanophosphors ZrO2 and Y2O3 [J]. Mater. Sci. Eng. B, 2010, 174(1):177-181. [10] Chen G Y, Somesfalean G, Liu Y, et al. Upconversion mechanism for two-color emission in rare-earth-ion-doped ZrO2 nanocrystals [J]. Phys. Rev. B, 2007, 75(19):195204-1-6. [11] [JP]Tikhomirov V K, Rodrguez V D, Mndez-Ramos J, et al. Optimizing Er/Yb ratio and content in Er-Yb co-doped glass-ceramics for enhancement of the up- and down-conversion luminescence [J]. Sol. Energy Mater. Sol. Cells, 2012, 100:209-215.[JP] [12] Silvaa M A P, Briois V, Poulain M, et al. SiO2-PbF2-CdF2 glasses and glass ceramics [J]. J. Phys. Chem. Solids, 2003, 64(1):95-105. [13] Del-Castillo J, Yanes A C, Mndez-Ramos J, et al. Structure and up-conversion luminescence in sol-gel derived Er3+-Yb3+ co-doped SiO2[DK]：PbF2 nano-glass-ceramics [J]. Opt. Mater., 2009, 32(1):104-107. [14] Yu H, Zhao L J, Liang Q, et al. Red up-conversion luminescence process in oxyfluoride glass ceramics doped with Er3+/Yb3+ [J]. Chin. Phys. Lett., 2005, 22(6):1500-1503. [15] Zhang G, Song F, Ming C G, et al. Photoluminescence properties and pump-saturation effect of Er3+/Yb3+ co-doped Y2Ti2O7 nanocrystals [J]. J. Lumin., 2012, 132:774-779. [16] Luo L, Zhang X X, Li K F, et al. Er/Yb doped porous siliconA novel white light source [J]. Adv. Mater., 2004, 16(18):1664-1667. [17] Strohhofer C, Polman A. Absorption and emission spectroscopy in Er3+-Yb3+ doped aluminum oxide waveguides [J]. Opt. Mater., 2003, 21(4):705-712. [18] Hu N, Yu H, Zhang M, et al. The tetragonal structure of nanocrystals in rare-earth doped oxyfluoride glass ceramics [J]. Phys. Chem. Chem. Phys., 2011, 13(4):1499-1505. [19] Pollnau M, Gamelin D R, Luthi S R, et al. Power dependence of upconversion luminescence in lanthanide and transition-metal-ion systems [J]. Phys. Rev. B, 2000, 61(5):3337-3346. [20] Huang P, Liu F, Chen D Q, et al. Highly efficient near-infrared to visible upconversion luminescence in transparent glass ceramics containing Yb3+/Er3+[DK]：NaYF4 nanocrystals [J]. Phys. Stat. Sol. (a), 2008, 205(7):1680-1684. [21] Dexter D L. A theory of sensitized luminescence in solids [J]. J. Chem. Phys., 1953, 21(5):836-850.