[1] X. S. Wang, Q. H. Nie, T. F. Xu et al.. Tm3+/Yb3+ co-doped tellurite glass for broadband optical amplifying over S+L bands［J］. Spectrochim. Acta Part A, 2009, 72(3): 543～546
[2] Z. Z. Chen, F. Song, C. G. Zou et al.. Numerical investigation of gain charateristics of Er3+/Yb3+ co-doped fiber amplifiers［J］. Opt. Quant. Electron., 2009, 40(13): 1021～1031
[3] H. Chen, Y. H. Liu, Y. F. Zhou et al.. Spectroscopic properties of Er3+ doped TeO2-BaO(Li2O,Na2O)-La2O3 glasses for 1.5-μm optical amplifiers［J］. J. Non-Cryst. Solids, 2005, 351(37-39): 3060～3064
[4] J. B. Qiu, Z. G. Song. Nanocrystals precipitation and up-conversion luminescence in Yb3+-Tm3+ co-doped oxyfluoride glasses［J］. J. Rare Earth, 2008, 6(26): 919～923
[5] Lin Qiongfei, Xia Haiping, Wang Jinhao et al.. Spectral properties of Tm3+-doped SiO2-Al2O3-PbF2-AlF3 glasses［J］. Acta Optica Sinica, 2008, 28(2): 306～310
[6] G. S. Qin, W. P. Qin, C. F. Wu et al.. Infrared-to-visible upconversion luminescence of Er3+ and Yb3+ co-doped germanate glass［J］. J. Non-Cryst. Solids, 2004, 347(1-3): 52～55
[7] S. X. Dai, B. Peng, P. J. Zhang et al.. The near- and mid-infrared emission properties of Tm3+-doped GeGaS-CsI chalcogenide glasses［J］. J. Non-Cryst. Solids, 2010, 356(44-49): 2424～2428
[8] L. Xu, B. Song, S. C. Xiao et al.. Up-conversion luminescence of Tm3+/Yb3+ co-doped oxy-fluoride glasses［J］. J. Rare Earth, 2010, 28(2): 194～197
[9] Zhao Yaxun, Wang Jun, Chen Fen et al.. Preparation and spectral properties of Er3+/Ce3+ codoped bismuth-germanate glass and the fibers［J］. J. Optoelectronics·Laser, 2009, 20(2): 208～211
[10] L. Y. Zhang, N. K. Chen, L. L. Hu. High Er3+ concentration low refractive index fluorophosphate glass for evanescent wave optical amplifiers［J］. Physica B, 2008, 403(19-20): 3470～3472
[11] H. Y. Meng, W. Q. Gao, Y. G. Liu et al.. The gain and noise figure improvement of reflection L-band erbium-doped fiber amplifier［J］. Opt. Commun., 2003, 288(1-3): 85～89
[12] S. H. Xu, Z. M. Yang, Z. M. Feng et al.. Efficient fibre amplifiers based on a highly Er3+/Yb3+ codoped phosphate glass-fibre［J］. Chin. Phys. Lett., 2009, 26(4): 047806
[13] J. F. Li, K. L. Duan, Y. S. Wang et al.. Modeling and optimizing of high-concentration erbium-doped fiber amplifiers with consideration of ion-clusters［J］. Opt. Commun., 2007, 277(1): 143～149
[14] Yin Bing, Yang Zhongmin, Yang Gangfeng et al.. Characteristic of 2.0 μm fluorescence dominated by the cross-relaxation of Tm3+ in Tm3+/Ho3+ co-doped tellurite glasses［J］. J. Chin. Ceram. Soc., 2007, 35(7): 913～917
[15] X. L. Liang, S. L. Yuan, Y. X. Yang et al.. The luminescence properties of Er3+-doped and Er3+-Tm3+-co-doped phosphate glasses for white light emitting diode［J］. J. Lumin., 2010, 130(3): 429～433
[16] Q. Qian, Y. Wang, Q. Y. Zhang et al.. Spectrocopic properties of Er3+-doped Na2O-Sb2O3-B2O3-SiO2 glasses［J］. J. Non-Cryst. Solids, 2008, 354(18): 1981～1985
[17] Y. H. Wang, C. S. Ma, D. L. Li et al.. Effects of styles on power conversion efficiency and gain characteristics of phosphate glass Er3+-Yb3+-co-doped waveguide amplifiers ［J］. Opt. & Laser Technol., 2009, 41(5): 545～549
[18] H. Ping, D. Q. Chen, Y. L. Yu et al.. Judd-ofelt analyses and luminescence of Er3+/Yb3+ co-doped transparent glass ceramics containing NaYF4 nanocrystals［J］. J. Alloys Compd., 2010, 490(1-2): 74～77
[19] G. Lakshminarayana, H. C. Yang, S. Ye et al.. Co-operative downconversion luminescence in Tm3+/Yb3+SiO2-Al2O3-LiF-GdF3 glasses［J］. J. Phys. D: Appl. Phys., 2008, 41(17): 175111
[20] J. Chang, Q. P. Wang, G. D. Peng et al.. Gain improvement by internal laser cavity in Tm3+/Yb3+-codoped tellurite fiber amplifier pumped by 980-nm laser［J］. Opt. Express, 2006, 14(19): 8535～8539
[21] Sun Jiangting, Zhang Jiahua, Luo Yongshi et al.. Spectra and its bandwidth of the 1. 5 μm emission in Er3+-doped glass［J］. J. Optoelectronics·Laser, 2003, 14(9): 992～995
[22] D. M. Shi, Q. Qian. Spectroscopic properties and energy transfer in Ga2O3-Bi2O3-PbO-GeO2 glasses doped with Er3+ and Tm3+［J］. Physica B, 2010, 405(11): 2503～2507
[24] Chen Baojiu, Lü Shaozhe, Qin Weiping et al.. Calculation of optical properties of Tm3+ in MFT glass by JO theory［J］. Acta Photonica Sinica, 1999, 28(7): 667～670
[25] S. Q. Man, S. F. Wong, E. Y. B. Pun et al.. 1.47-μm emission and multiphonon relaxation of Tm3+ ions in potassium bismuth gallate glasses［J］. J. Opt. Soc. Am. B, 2004, 21(2): 313～317
[26] R. Scarmozzino, R. M. Osgood. Comparison of finite-difference and Fourier-transform solutions of the parabolic wave equation with emphasis on integratedoptics applications［J］. J. Opt. Soc. Am. A, 1991, 8(5): 724～731
[27] W. J. Song, G. H. Song, B. H. Ahn et al.. Scalar BPM analyses of TE and TM polarized fields in bent waveguides［J］. IEEE Trans. Antennas Propag., 2003, 51(6): 1185～1197
[28] C. Ma, E. V. Keuren. A three-dimensional wide-angle BPM for optical waveguide structures［J］. Opt. Express, 2007, 15(2): 402～407
[29] BeamPROP (Rsoft Incorporated, 2003)
[30] R. T. Schermer, J. H. Cole. Improved bend loss formula verified for optical fiber simulation and experiment［J］. IEEE J. Quantum Electron., 2007, 43(10): 899～909
[31] M. Heiblum, J. H. Harris. Analysis of curved optical waveguides by conformal transformation［J］. IEEE J. Quantum Electron., 1975, QE11(2): 75～83
[32] R. Baets, P. E. Lagasse. Loss calculation and design of arbitrarily curved integrated-optic waveguides［J］. J. Opt. Soc. Am., 1983, 73(2): 177～182
[33] D. L. Yang, E. Y. B. Pun, N. Q. Wang et al.. Radiation and gain behaviors in Tm3+-doped aluminum germanate substrate glasses and thermal ion-exchanged waveguide［J］. J. Opt. Soc. Am. B, 2010, 27(5): 1～7
[34] V. Astley, J. Scheiman, R. Mendis et al.. Bending and coupling losses in terahertz wire waveguides［J］. Opt. Lett., 2010, 35(4): 553～555
[35] R. K. Navalakhe, N. D. Gupta, B. K. Das. Fabrication and characterization of straight and compact S-bend optical waveguides on a silicon-on-insulator platform［J］. Appl. Opt., 2009, 48(31): G125～G130
[36] A. H. Liang. Relation between transition loss and mode-field half-width for curved noncircular weakly-guiding single-mode waveguides［J］. IEEE J. Quantum Electron., 1995, 31(11): 2075～2077
[37] T. Kitoh, N. Takato, M. Yasu et al.. Bending loss reduction in silica-based waveguides by using lateral offsets［J］. J. Lightwave Technol., 1995, 13(4): 555～562
