[6] [6] CHOI J H, SHI F G, MARGARYAN A A, et al. Optical absorption and emission properties of Nd3+ doped fluorophosphates glass for broadband fiber amplifier applications[J]. Proceedings of SPIE-The International Society for Optical Engineering, 2003, 4974: 106-111.

[8] [8] YANG P, CHEN Z, CHEN N, et al. Raman scattering enhancement characteristic of NbCl5- and Nb2O5-doped silica fibers[J]. Chinese Optics Letters, 2016, 14(10): 20-23.

[12] [12] GE J, WANG J, ZHANG H, et al. Orthogonal PbS nanowire arrays and networks and their Raman scattering behavior[J]. Chemistry - A European Journal, 2010, 11(6): 1889-1894.

[13] [13] BARANOV A V, BOGDANOV K V, USHAKOVA E V, et al. Comparative analysis of Raman spectra of PbS macro- and nanocrystals[J]. Optics & Spectroscopy, 2010, 109(2): 268-271.

[14] [14] OVSYANNIKOV S V, SHCHENNIKOV V V, CANTARERO A, et al. Raman spectra of (PbS)1.18(TiS2)2 misfit compound[J]. Materials Science & Engineering A, 2007, 462(1): 422-426.

[15] [15] SMITH G D, FIRTH S, CLARK R J H, et al. First- and second-order Raman spectra of galena (PbS)[J]. Journal of Applied Physics, 2002, 92(8): 4375-4380.