[1] [1] M Shirk, P Molian. A review of ultrashort pulsed laser ablation of materials[J]. J Laser Appl, 1998, 10(1): 18-28.

[2] [2] R G Rafaelf, M Eric. Femtosecond laser micromachining in transparent materials[J]. Nature Photonics, 2008, 2: 219-225.

[3] [3] J R Vazquez de Aldana, P Moreno, L Roso. Ultrafast lasers: A new frontier for optical materials processing[J]. Opt Mater, 2012, 34(3): 572-578.

[4] [4] K M Davis, K Miura, N Sugimoto, et al.. Writing waveguides in glass with a femtosecond laser[J]. Opt Lett, 1996, 21(21): 1729-1731.

[5] [5] M Lenzner, J Kruger, S Sartania, et al.. Femtosecond optical breakdown in dielectrics[J]. Phys Rev Lett, 1998, 80(18): 4076-4079.

[6] [6] Li Dongjuan, Lin Ling, Lü Baida, et al.. Polarization- dependent optical guiding in low repetition frequency femtosecond laser photowritten type II fused silica waveguides[J]. Acta Optica Sinica, 2013, 33(5): 0532001.

[7] [7] Xuewen Long, Jing Bai, Xin Liu, et al.. Buried waveguide in neodymium-doped phosphate glass obtained by femtosecond laser writing using a double line approach[J]. Chin Opt Lett, 2013, 11(10): 102301.

[8] [8] Hou Fang, Li Weinan, Bai Jing, et al.. Femtosecond- laser- written waveguide in magnetic- optical glass[J]. Acta Optica Sinica, 2013, 33(3): 0314002.

[9] [9] T Calmano, A G Paschke, J Siebenmorgen, et al.. Characterization of an Yb:YAG ceramic waveguide laser, fabricated by the direct femtosecond-laser writing technique[J]. Appl Phys B, 2011, 103(2): 1-4.

[10] [10] Long Xuewen, Bai Jing, Liu Xin, et al.. Inscription of waveguides in terbium gallium garnet using femtosecond laser[J]. Acta Optica Sinica, 2014, 34(4): 0432002.

[11] [11] C Mauclair, G Cheng, N Huot, et al.. Dynamic ultrafast laser spatial tailoring for parallel micromachining of photonic devices in transparent materials[J]. Opt Express, 2009, 17(5): 3531-3542.

[12] [12] A M Streltsov, N F Borrelli. Fabrication and analysis of a directional coupler written in glass by nanojoule femtosecond laser pulses [J]. Opt Lett, 2001, 26(1): 42-43.

[13] [13] Liu J, Zhang Z, Chang S, et al.. Directly writing of 1- to- N optical waveguide power splitters in fused silica glass using a femtosecond laser[J]. Opt Commun, 2005, 253(4): 315-319.

[14] [14] G D Marshall, M Ams, M J Withford. Direct laser written waveguide-Bragg gratings in bulk fused silica[J]. Opt Lett, 2006, 31(18): 2690-2691.

[15] [15] Lin Ling, Yang Xiaojun, Bai Jing, et al.. Femtosecond laser photoinscription of waveguide polarizer[J]. Acta Photonic Sinica, 2011, 40(6): 818-822.

[16] [16] J Siebenmorgen, T Calmano, K Petermann, et al.. Highly efficient Yb∶YAG channel waveguide laser written with a femtosecond laser [J]. Opt Express, 2010, 18(15): 16035-16041.

[17] [17] R Mary, S J Beecher, G Brown, et al.. Compact, highly efficient ytterbium doped bismuthate glass waveguide laser[J]. Opt Lett, 2012, 37(10): 1691-1693.

[18] [18] Dai Shixun, Hu Lili, Liu Zhuping, et al.. Spectrum and laser properties of ytterbium doped phosphate glass at low temperature[J]. Acta Optica Sinica, 2002, 22(5): 627-631.

[19] [19] C Jiang, H Liu, Q Zeng, et al.. Yb∶phosphate laser glass with high emission cross-section[J]. J Phys Chem Solids, 2000, 61(8): 1217-1223.

[20] [20] M Ams, P Dekker, G D Marshall, et al.. Monolithic 100 mW Yb waveguide laser fabricated using the femtosecond-laser directwrite technique[J]. Opt Lett, 2009, 34(3): 247-249.

[21] [21] G Cerullo, R Osellame, S Taccheo, et al.. Femtosecond micromachining of symmetric waveguides at 1.5 μm by astigmatic beam focusing[J]. Opt Lett, 2002, 27(21): 1938-1941.

[22] [22] Bai Jing, Long Xuewen, Liu Xin, et al.. Experimental study of femtosecond laser written waveguide in Yb3 +∶phosphate glass and waveguide laser[J]. Acta Optica Sinica, 2014, 34(4): 0432003.

[23] [23] F Caccavale, F Segato, I Mansour, et al.. A finite differences method for the reconstruction of refractive index profiles from nearfield measurements[J]. J Lightwave Technol, 1998, 16(7): 1348-1353.

[24] [24] S V Rao, K Moutzouris, M Ebrahimzadeh, et al.. Measurements of optical loss in GaAs/Al2O3 nonlinear waveguides in the infrared using femtosecond scattering technique[J]. Opt Commun, 2002, 213: 223-228.

[25] [25] J Burghoff, S Nolte, A Tunnermann. Origins of waveguiding in femtosecond laser-structured LiNbO3[J]. Appl Phys A, 2007, 89(1): 127-132.