[1] [1] Hamzaoui M, Soltani M T, Baazouzi M, et al. Physica Status Solidi, 2012, 249: 2213.

[2] [2] Fan B, Xue B, Zhang X, et al. Optics Letters, 2013, 38: 2280.

[3] [3] Sun C Y, Wang X L, Zhang X, et al. Nature Communications, 2013, 4: 2717.

[4] [4] Babu B H, Kumar V V R K. Journal of Materials Science, 2014, 49: 415.

[5] [5] Messing G L, Zhang S C, Jayanthi G V. Journal of the American Ceramic Society, 1993, 76: 2707.

[6] [6] Yu Y, Liu Z, Dai N, et al. Optics Express, 2011, 19: 19473.

[7] [7] Samsudin N F, Matori K A, Wahab Z A, et al. Optik-International Journal for Light and Electron Optics, 2016, 127: 8076.

[8] [8] Kumar M V S, Rajesh D, Balakrishna A, et al. Journal of Molecular Structure, 2013, 1041: 100.

[9] [9] Yuan Y, Zheng R, Lu Q, et al. Optics Letters, 2016, 41: 3122.

[10] [10] Vincent A C, Scott P. Journal of Cosmology & Astroparticle Physics, 2014, (4): 19.

[11] [11] Babu P, Jang K H, Rao C, et al. Optics Express, 2011, 19(3): 1836.

[12] [12] Kesavulu C R, Jayasankar C K. Materials Chemistry & Physics, 2011, 130(3): 1078.

[13] [13] Okamoto H, Kasuga K, Kubota Y, et al. Optics Express, 2013, 21(19): 22043.

[14] [14] Vijaya N, Upendra K K, Jayasankar C K. Spectrochimica Acta Part A Molecular & Biomolecular Spectroscopy, 2013, 113: 145.

[15] [15] Rosemann N W, Eu ner J P, Beyer A, et al. Science, 2016, 352: 1301.