[1] [1] Vincent F, Martin B, Bah S T, et al. 30 W fluoride glass all-fiber laser at 2.94 μm［J］. Optics Letters, 2015, 40(12): 2882-2885.

[2] [2] Percival R M, Szebesta D, Seltzer C P, et al. A 1.6-μm pumped 1.9-μm thulium-doped fluoride fiber laser and amplifier of very high efficiency［J］. IEEE Journal of Quantum Electronics, 1995, 31(3): 489-493.

[3] [3] Hfer S, Liem A, Limpert J, et al. Single-frequency master-oscillator fiber power amplifier system emitting 20 W of power［J］. Optics Letters, 2001, 26(17): 1326-1328.

[4] [4] Clément Q, Melkonian J M, Barrientos-Barria J, et al. Tunable optical parametric amplification of a single-frequency quantum cascade laser around 8 μm in ZnGeP2［J］. Optics Letters, 2013, 38(20): 4046-4049.

[5] [5] Stutzki F, Gaida C, Gebhardt M, et al. 152 W average power Tm-doped fiber CPA system［J］. Optics Letters, 2014, 39(16): 4671-4674.

[6] [6] Wang X, Zhou P, Zhang H W, et al. 100 W-level Tm-doped fiber laser pumped by 1173 nm Raman fiber lasers［J］. Optics Letters, 2014, 39(15): 4329-4332.

[7] [7] Hutcheon R J, Perrett B J, Mason P D. Modeling of thermal effects within a 2 μm pumped ZGP optical parametric oscillator operating in the mid-infrared［C］. SPIE, 2004, 5620: 264-274.

[8] [8] Lippert E, Rustad G, Nicolas S, et al. Fibre-laser-pumped mid-infrared source［C］. SPIE, 2004, 5620: 56-62.

[9] [9] Liu J, Shi H X, Liu K, et al. 210 W single-frequency, single-polarization, thulium-doped all-fiber MOPA［J］. Optics Express, 2014, 22(11): 13572-13578.

[10] [10] Goodno G D, Book L D, Rothenburg J E. Low-phase-noise, single-frequency, single-mode 608 W thulium fiber amplifier［J］. Optics Letters, 2009, 34(8): 1204-1206.

[11] [11] Zyskind J L, Sulhoff J W, Sun Y, et al. Single mode diode-pumped tunable erbium-doped fiber laser with linewidth less than 5.5 kHz［J］. Electronics Letters, 1991, 27(23): 2148-2149.

[12] [12] Lu Z G, Grover C P. A widely tunable narrow-linewidth triple-wavelength erbium-doped fiber ring laser［J］. IEEE Photonics Technology Letters, 2005, 17(1): 22-24.

[13] [13] Feng Z M, Mo S P, Xu S H, et al. A compact linearly polarized low-noise single-frequency fiber laser at 1064 nm［J］. Applied Physics Express, 2013, 6(5): 052701.

[14] [14] Poulsen C V, Sejka M. Highly optimized tunable Er3+-doped single longitudinal mode fiber ring laser, experiment and model［J］. IEEE Photonics Technology Letters, 1993, 5(6): 646-648.

[15] [15] Zhang W N, Li C, Mo S P, et al. A compact low noise single frequency linearly polarized DBR fiber laser at 1550 nm［J］. Chinese Physics Letters, 2012, 29(8): 084205.

[16] [16] Xu S H, Yang Z M, Liu T, et al. An efficient compact 300 mW narrow-linewidth single frequency fiber laser at 1.5 μm［J］. Optics Express, 2010, 18(2): 1249-1254.

[17] [17] Lwatsuki K, Okamura H, Saruwatari M. Wavelength-tunable single-frequency and single-polarisation Er-doped fiber ring-laser with 1.4 kHz linewidth［J］. Electronics Letters, 1990, 26(24): 2033-2035.

[18] [18] Spiegelberg C, Geng J, Hu Y D, et al. Low-noise narrow-linewidth fiber laser at 1550 nm［J］. Journal of Lightwave Technology, 2004, 22(1): 57-62.

[19] [19] Xu S H, Yang Z M, Zhang W N, et al. 400 mW ultrashort cavity low-noise single-frequency Yb3+-doped phosphate fiber laser［J］. Optics Letters, 2011, 36(18): 3708-3710.

[20] [20] Babin S A, Churkin D V, Kablukov S I, et al. Single frequency linearly polarized DFB fiber laser source［C］. SPIE, 2007, 6727: 672716.

[21] [21] Agger S, Povlsen J H, Varming P. Single-frequency thulium-doped distributed-feedback fiber laser［J］. Optics Letters, 2004, 29(13): 1503-1505.

[22] [22] Geng J H, Wang Q, Luo T, et al. Single-frequency narrow-linewidth Tm-doped fiber laser using silicate glass fiber［J］. Optics Letters, 2009, 34(22): 3493-3495.

[23] [23] Voo N Y, Sahu J K, Ibsen M. 345-mW 1836-nm single-frequency DFB fiber laser MOPA［J］. IEEE Photonics Technology Letters, 2005, 17(12): 2550-2552.

[24] [24] Gapontsev D, Platonov N, Meleshkevich M, et al. 20 W single-frequency fiber laser operating at 1.93 μm［C］. Conference on Lasers & Electro-Optics, 2007, 15(25): CF15.

[25] [25] Shen D Y, Zhang Z, Boyland A J, et al. Thulium-doped distributed-feedback fiber laser with >0.3 W output at 1935 nm［C］. Bragg Gratings, Photosensitivity, and Poling in Glass Waveguides, 2007: BTuC1.

[26] [26] Zhang Z, Shen D Y, Boyland A J, et al. High-power Tm-doped fiber distributed-feedback laser at 1943 nm［J］. Optics Letters, 2008, 33 (18): 2059-2061.

[27] [27] Zhang Z, Boyland A J, Sahu J K, et al. Single-frequency Tm-doped fiber master-oscillator power-amplifier with 10 W linearly polarized output at 1943 nm［C］. Conference on Lasers and Electro-Optics, 2008: CFD5.

[28] [28] Pearson L, Kim J W, Zhang Z, et al. High-power linearly-polarized single-frequency thulium-doped fiber master-oscillator power-amplifier［J］. Optics Express, 2010, 18(2): 1607-1612.

[29] [29] Wu J F, Yao Z D, Zong J, et al. Highly efficient high-power thulium-doped germanate glass fiber laser［J］. Optics Letters, 2007, 32(6): 638-640.

[30] [30] Wen X, Tang G W, Wang J W, et al. Tm3+ doped barium gallo-germanate glass single-mode fibers for 2.0 μm laser［J］. Optics Express, 2015, 23(6): 7722-7731.

[31] [31] Yang C S, Chen D, Xu S H, et al. Short all Tm-doped germanate glass fiber MOPA single-frequency laser at 1.95 μm［J］. Optics Express, 2016, 24(10): 10956-10961.

[32] [32] Geng J, Wu J, Jiang S B, et al. Efficient operation of diode-pumped single-frequency thulium-doped fiber lasers near 2 μm［J］. Optics Letters, 2007, 32(4): 355-357.

[33] [33] Yang Q, Xu S H, Li C, et al. A single-frequency linearly polarized fiber laser using a newly developed heavily Tm3+-doped germanate glass fiber at 1.95 μm［J］. Chinese Physics Letters, 2015, 32(9): 094206.

[34] [34] Yu S L, Yang Z M, Xu S H. Spectroscopic properties and energy transfer analysis of Tm3+-doped BaF2-Ga2O3-GeO2-La2O3 glass［J］. Journal of Fluorescence, 2010, 20(3): 745-751.

[35] [35] Wen X, Tang G W, Yang Q, et al. Highly Tm3+ doped germanate glass and its single mode fiber for 2.0 μm laser［J］. Scientific Reports, 2016, 6: 20344.

[36] [36] Higby P L, Aggarwal I D. Properties of barium gallium germanate glasses［J］. Journal of Non-Crystalline Solids, 1993, 163(3): 303-308.

[37] [37] Xu R R, Tian Y, Hu L L, et al. Enhanced emission of 2.7 μm pumped by laser diode from Er3+/Pr3+-codoped germanate glasses［J］. Optics Letters, 2011, 36(7): 1173-1175.

[38] [38] Srivastava S, Gopal R, Sai S, et al. Feedback Mach-Zehnder resonator with “reflector:”Analysis and applications in single frequency fiber lasers［J］. Applied Physics Letters, 2006, 89(14): 141118.

[39] [39] Sun J Q, Huang L. Single-longitudinal-mode fiber ring laser using internal lasing injection and self-injection feedback［J］. Optical Engineering, 2007, 46(7): 074201.

[40] [40] Srivastava S, Srinivasan K. Coupled-cavity analysis of the resonant loop mirror: Closed-form expressions and simulations for enhanced performance lasing［J］. Applied Optics, 2005, 44(4): 572-581.

[41] [41] Yeh C H, Shih F Y, Lee C N, et al. Wavelength-tunable erbium fiber ring laser in single-frequency operation utilizing Fabry-Perot laser with Sagnac cavity［J］. Optics Communications, 2008, 281(9): 2454-2458.

[42] [42] Feng T, Yan F P, Peng W J, et al. A high stability wavelength-tunable narrow-linewidth and single-polarization erbium-doped fiber laser using a compound-cavity structure［J］. Laser Physics Letters, 2014, 11 (4): 045101.

[43] [43] Yin M J, Huang S H, Lu B L, et al. Slope efficiency over 30% single-frequency ytterbium-doped fiber laser based on Sagnac loop mirror filter［J］. Applied Optics, 2013, 52(27): 6799-6803.

[44] [44] Park N, Dawson J W, Vahala K J, et al. All fiber, low threshold, widely tunable single-frequency, erbium-doped fiber ring laser with a tandem fiber Fabry-Perot filter［J］. Applied Physics Letters, 1991, 59 (19): 2369-2371.

[45] [45] He X, Xu S H, Li C, et al. 1.95 μm kHz-linewidth single-frequency fiber laser using self-developed heavily Tm3+-doped germanate glass fiber［J］. Optics Express, 2013, 21(18): 20800-20805.

[46] [46] Zhang Z, Boyland A J, Sahu J K, et al. High-power single-frequency thulium-doped fiber DBR laser at 1943 nm［J］. IEEE Photonics Technology Letters, 2011, 23(7): 417-419.

[47] [47] Fu S J, Shi W, Lin J C, et al. Single-frequency fiber laser at 1950 nm based on thulium-doped silica fiber［J］. Optics Letters, 2015, 40(22): 5283-5286.

[48] [48] Gray S, Liu A, Walton D T, et al. 502 Watt, single transverse mode, narrow linewidth, bidirectionally pumped Yb-doped fiber amplifier［J］. Optics Express, 2007, 15(25): 17044-17050.

[49] [49] Wang X L, Zhou P, Xiao H, et al. 310 W single-frequency all-fiber laser in master oscillator power amplification configuration［J］. Laser Physics Letters, 9(8): 591-595.

[50] [50] Yin K, Zhu R Z, Zhang B, et al. 300 W-level, wavelength-widely-tunable, all-fiber integrated thulium-doped fiber laser［J］. Optics Express, 2016, 24(10): 11085-11090.

[51] [51] Wang X, Zhou P, Wang X L, et al. 102 W monolithic single frequency Tm-doped fiber MOPA［J］. Optics Express, 2013, 21(26): 32386-32392.

[52] [52] Barnes N P, Walsh B M, Reichle D J, et al. Tm: germanate fiber laser: Tuning and Q-switching［J］. Applied Physics B, 2007, 89(2): 299-304.