[8] [8] PAN Yu, Research on ultra-high Q whispering gallery mode resonators[D]. Hangzhou: Zhejiang University, 2017.

[9] [9] SHEN Yuan. Research on optical frequency comb generation in magnesium fluoride micro-resonator[D]. Hefei: University of Science and Technology of China, 2021.

[10] [10] LU Xiaoyun. The fabrication and coupling test of high Q value calcium fluoride disk[D]. Taiyuan: North University of China, 2016.

[11] [11] YANG Xu. Raman modulation of whispering Gallery mode microresonators and its application[D]. Beijing: Tsinghua University, 2016.

[12] [12] LIN G P, RÉMI H, AURÉLIEN C, et al. Dependence of quality factor on surface roughness in crystalline whispering-gallery mode resonators[J]. Optical Letters, 2018, 43(3): 495-498.