[1] [1] Kaiser W, Garrett C G B, Wood D L. Fluorescence and optical maser effects in CaF2∶Sm++［J］. Phys Rev, 1961, 123(3): 766-776.

[2] [2] Sorokin P P, Stevenson M J. Stimulated infrared emission from trivalent uranium［J］. Phys Rev Lett, 1960, 5(12): 557-559.

[3] [3] Orlovskii Y V, Basiev T T, Osiko V V, et al. Fluorescence line narrowing (FLN) and site-selective fluorescence decay of Nd3+ centers in CaF2［J］. J Lumin, 1999, 82(3): 251-258.

[4] [4] Voronko Y K, Osiko V V, Shcherbakov I A. Investigation of the interaction of Nd3+ ions in CaF2, SrF2 and BaF2 crystals (type I)［J］. Sov Phys JETP, 1969, 28(5): 838-844.

[5] [5] Voronko Y K, Kaminskii A A, Osiko V V. Analysis of the optical spectra of CaF2∶Nd3+ (type 1) crystals［J］. Sov Phys JETP, 1966, 22(2): 295-300.

[6] [6] Han T P J, Jones G D, Syme R W G. Site-selective spectroscopy of Nd3+ centers in CaF2∶Nd3+ and SrF2∶Nd3+［J］. Phys Rev B, 1993, 47(22): 14706-14723.

[7] [7] Alimov O K, Basiev T T, Doroshenko M E, et al. Investigation of Nd3+ ions spectroscopic and laser properties in SrF2 fluoride single crystal［J］. Opt Mater, 2012, 34(5): 799-802.

[8] [8] Friebel F, Druon F, Boudeile J, et al. Diode-pumped 99 fs Yb∶CaF2 oscillator［J］. Opt Lett, 2009, 34(9): 1474-1476.

[9] [9] Siebold M, Hornung M, Boedefeld R, et al. Terawatt diode-pumped Yb∶CaF2 laser［J］. Opt Lett, 2008, 33(23): 2770-2772.

[10] [10] Su L B, Wang Q G, Li H J, et al. Spectroscopic properties and CW laser operation of Nd, Y-codoped CaF2 single crystals［J］. Laser Phys Lett, 2013, 10(3): 035804.

[11] [11] Doualan J L, Su L B, Brasse G, et al. Improvement of infrared laser properties of Nd∶CaF2 crystals via codoping with Y3+ and Lu3+ buffer ions［J］. J Opt Soc Am B, 2013, 30(11): 3018-3021.

[12] [12] Zhang C, Hou Z, Chai R, et al. Mesoporous SrF2 and SrF2∶Ln3+ (Ln=Ce, Tb, Yb, Er) hierarchical microspheres: Hydrothermal synthesis, growing mechanism, and luminescent properties［J］. J Phys Chem C, 2010, 114(15): 6928-6936.

[13] [13] Chen D, Yu Y, Huang F, et al. Modifying the size and shape of monodisperse bifunctional alkaline-earth fluoride nanocrystals through lanthanide doping［J］. J Am Chem Soc, 2010, 132(29): 9976-9978.

[14] [14] Wang Xiaofa, Fan Zhongwei, Yu Jin, et al. High energy and high efficiency Nd∶glass regenerative amplifier［J］. Chinese J Lasers, 2012, 39(8): 0802002.

[15] [15] Tang Jingping, Hu Lili, Chen Shubin, et al. Properties of large size N31 Nd∶phosphate laser glass prepared by continuous melting［J］. Chinese J Lasers, 2015, 42(2): 0206003.

[16] [16] Liu Jian, Liu Junfang, Su Liangbi, et al. Effects of Gd3+/Y3+ co-doping on the spectral properties of Nd∶CaF2 crystals［J］. Acta Physica Sinica, 2016, 65(5): 054207.

[17] [17] Ma F K, Jiang D P, Su L B, et al. Spectral properties and highly efficient continuous-wave laser operation in Nd-doped Sr1-xYx F2+x crystals［J］. Optics Letters, 2016, 41(3): 501-503.

[18] [18] Cui Chengjia, Liu Zhanguo, Zhu Haidong. Habit of fluoride under heating and crystal growth［J］. Journal of Synthetic Crystals, 1997, 3(3-4): 323.

[19] [19] Zhang Xiangyu, Li Lin, Mao Duolu, et al. Rare-earth doped fluoride nanocrystals: Grown mechanism and spectroscopy property［J］. Scientia Sinica (Physica, Mechanica & Astronomica), 2013, 43(1): 23-30.

[21] [21] Cui Chengjia, Ogawa Tomoya. Growth and characterization of large CaF2 single crystals［J］. Journal of Synthetic Crystals, 1991, 20(1): 46-54.

[22] [22] Cheng Zhaonian, Zhang Jing, Jia Zhengming, et al. Ca2+ sublattice and F- sublattice in superionic conductor CaF2［J］. Acta Physico-Chimica Sinica, 1991, 7(4): 390-393.

[23] [23] Shigeru S, Tsutomu M, Kazuo K, et al. A manufacturing method for calcium fluoride and calcium fluoride for photolithography: EP0939147B1［P］. 2003-09-03.