[1] Gaimard Q, Triki M, Nguyen-Ba T, et al. Distributed feedback GaSb based laser diodes with buried grating: a new field of single-frequency sources from 2 to 3 μm for gas sensing applications[J]. Optics Express, 2015, 23(15): 19118-19128.

[2] Koopmann P, Lamrini S, Scholle K, et al. Holmium-doped Lu2O3, Y2O3, and Sc2O3 for lasers above 21 μm[J]. Optics Express, 2013, 21(3): 3926-3931.

[3] Zhao J Q, Li Y, Zhang S, et al. Diode-pumped actively Q-switched Tm∶YAP/BaWO4 intracavity Raman laser[J]. Optics Express, 2015, 23(8): 10075-10080.

[4] Jiao Z X, He G Y, Guo J, et al. High average power 2 μm generation using an intracavity PPMgLN optical parametric oscillator[J]. Optics Letters, 2012, 37(1): 64-66.

[5] Stievater T H, Mahon R, Park D, et al. Mid-infrared difference-frequency generation in suspended GaAs waveguides[J]. Optics Letters, 2014, 39(4): 945-948.

[6] Pask H M. The design and operation of solid-state Raman lasers[J]. Progress in Quantum Electronics, 2003, 27(1): 3-56.

[7] Pask H M, Dekker P, Mildren R P, et al. Wavelength-versatile visible and UV sources based on crystalline Raman lasers[J]. Progress in Quantum Electronics, 2008, 32(3/4): 121-158.

[8] Zhang X L, Ding Y, Qiao Y, et al. Diode-end-pumped efficient 2533 nm intracavity Raman laser with high peak power[J]. Optics Communications, 2015, 355: 433-437.

[9] Zhao J Q, Zhang X L, Guo X, et al. Diode-pumped actively Q-switched Tm, Ho∶GdVO4/BaWO4 intracavity Raman laser at 2533 nm[J]. Optics Letters, 2013, 38(8): 1206-1208.

[10] Kuzucu O. Watt-level, mid-infrared output from a BaWO4 external-cavity Raman laser at 2.6 μm[J]. Optics Letters, 2015, 40(21): 5078-5081.

[11] Wang X, Fan Z, Yu H H, et al. Characterization of ZnWO4 Raman crystal[J]. Optical Materials Express, 2017, 7(6): 1732-1744.

[12] Liu Y, Wang H, Chen G, et al. Analysis of Raman spectra of ZnWO4 single crystals[J]. Journal of Applied Physics, 1988, 64(9): 4651-4653.

[13] Band Y B, Ackerhalt J R, Krasinski J S, et al. Intracavity Raman lasers[J]. IEEE Journal of Quantum Electronics, 1989, 25(2): 208-213.