硅基集成光波导放大器的最新研究进展
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摘要
在信息化进程中,随着摩尔定律越来越接近极限,将微电子和光电子结合起来,开发硅基大规模光电子集成技术已经成为技术发展的必然和业界的普遍共识.在硅基光电子集成器件中,硅基光源是重中之重.虽然硅是间接带隙半导体材料,发光效率很低,但人们一直没有放弃制备硅基光源.硅基光源包括硅基光波导放大器、发光二极管、激光器等,其中硅基光波导放大器又是激光器的基础,是硅基光电子集成回路中不可或缺的器件,如果光波导放大器有足够高的净增益,在光波导放大器的两端设计合适的谐振腔就可以获得光泵的激光.本文着眼于硅基光波导放大器,介绍了目前硅基光波导放大器最主要的两个研究方向,即硅基混合集成Ⅲ- Ⅴ族半导体光波导放大器和硅基掺稀土离子光波导放大器.并分别讨论了这两个研究方向的原理、制备方法、发展过程等,列举了相关的典型研究成果,最后简单介绍了其他光放大技术,并做了相应的分析、总结和展望.
In the process of informatization, the Moore’s Law is getting closer to the limit. Combining microelectronics and optoelectronics to develop silicon-based large-scale integrated optoelectronic technology has become the industry consensus. It is also the inevitable direction of technology development. In recent years, silicon photonics has made great progress, many key devices have reached the commercial standard, and some of the performance is even higher than the current commercial device performance. In silicon based optoelectronic integrated devices, silicon based light source is the most important but has not yet been completely resolved. Although silicon is an indirect band gap semiconductor material and luminous efficiency is very low, people have not given up efforts to prepare silicon based light source. Silicon based light sources include silicon based optical waveguide amplifiers, light emitting diodes, lasers, etc., of which silicon based optical waveguide amplifier is the basis for lasers and the indispensable device in a silicon based optoelectronic integrated circuit. If the optical waveguide amplifier has a high net gain, optically pumped lasers can be obtained by designing the appropriate resonant cavities at both ends of the optical waveguide amplifier. In this paper, we focus on silicon based optical waveguide amplifier, introducing the two main research directions of silicon based waveguide amplifier, silicon based hybrid integrated III-V semiconductor optical waveguide amplifier and silicon based rare earth ion doped optical waveguide amplifier. This paper discusses the principle, preparation method and development process of these two research directions in detail respectively, and lists relevant typical research results. And we briefly introduce other optical amplification technology. Finally, summary and prospect are given.
In the process of informatization, the Moore’s Law is getting closer to the limit. Combining microelectronics and optoelectronics to develop silicon-based large-scale integrated optoelectronic technology has become the industry consensus. It is also the inevitable direction of technology development. In recent years, silicon photonics has made great progress, many key devices have reached the commercial standard, and some of the performance is even higher than the current commercial device performance. In silicon based optoelectronic integrated devices, silicon based light source is the most important but has not yet been completely resolved. Although silicon is an indirect band gap semiconductor material and luminous efficiency is very low, people have not given up efforts to prepare silicon based light source. Silicon based light sources include silicon based optical waveguide amplifiers, light emitting diodes, lasers, etc., of which silicon based optical waveguide amplifier is the basis for lasers and the indispensable device in a silicon based optoelectronic integrated circuit. If the optical waveguide amplifier has a high net gain, optically pumped lasers can be obtained by designing the appropriate resonant cavities at both ends of the optical waveguide amplifier. In this paper, we focus on silicon based optical waveguide amplifier, introducing the two main research directions of silicon based waveguide amplifier, silicon based hybrid integrated III-V semiconductor optical waveguide amplifier and silicon based rare earth ion doped optical waveguide amplifier. This paper discusses the principle, preparation method and development process of these two research directions in detail respectively, and lists relevant typical research results. And we briefly introduce other optical amplification technology. Finally, summary and prospect are given.
引文
[1] Zhou Z P. Silicon Photonics (in Chinese). Beijing: Peking University Press, 2012 [周治平. 硅基光电子学. 北京: 北京大学出版社, 2012]
2 Wang X J, Su Z T, Zhou Z P. Recent progress of silicon photonics (in Chinese). Sci Sin-Phys Mech Astron, 2015, 45: 014201 [王兴军, 苏昭棠, 周治平. 硅基光电子学的最新进展. 中国科学: 物理学力学天文学, 2015, 45: 014201]
3 Mason B, Barton J, Fish G A, et al. Design of sampled grating DBR lasers with integrated semiconductor optical amplifiers. IEEE Photon Technol Lett, 2000, 12: 762–764
4 Murthy S, Kato M, Nagarajan R, et al. Large-scale photonic integrated circuit transmitters with monolithically integrated semiconductor optical amplifiers. In: Proceedings of Optical Fiber Communication/National Fiber Optic Engineers Conference. New York: IEEE Press, 2008
5 Nagarajan R, Kato M, Hurtt S, et al. Monolithic, 10 and 40 channel InP receiver photonic integrated circuits with on-chip amplification. In: Proceedings of Optical Fiber Communication Conference. Anaheim: Optical Society of America Press, 2007. PDP32
6 Durhuus T, Mikkelsen B, Joergensen C, et al. All-optical wavelength conversion by semiconductor optical amplifiers. J Lightw Technol, 1996, 14: 942–954
7 Dutta N K, Wang Q. Semiconductor Optical Amplifiers. Singapore: World Scientific, 2006
8 Davenport M L, Skendzic S, Volet N, et al. Heterogeneous Silicon/III-V Semiconductor Optical Amplifiers. IEEE J Select Topics Quantum Electron, 2016, 22: 78–88
9 Wang H C, Huang L R, Shi Z W. Amplified spontaneous emission spectrum and gain characteristic of a two-electrode semiconductor optical amplifier. J Semicond, 2011, 32: 064010
10 Duan G H, Jany C, Le Liepvre A, et al. Hybrid III-V on silicon lasers for photonic integrated circuits on silicon. IEEE J Sel Top Quantum Electron, 2014, 20: 90020X
11 Hawkins A R, Wu W, Abraham P, et al. High gain-bandwidth-product silicon heterointerface photodetector. Appl Phys Lett, 1997, 70: 303–305
12 Liang D, Chapman D C, Li Y, et al. Uniformity study of wafer-scale InP-to-silicon hybrid integration. Appl Phys A, 2011, 103: 213–218
13 Adler F, Moutzouris K, Leitenstorfer A, et al. Phase-locked two-branch erbium-doped fiber laser system for long-term precision measurements of optical frequencies. Opt Express, 2004, 12: 5872–5880
14 Keyvaninia S, Muneeb M, Stankovi? S, et al. Ultra-thin DVS-BCB adhesive bonding of III-V wafers, dies and multiple dies to a patterned silicon-on-insulator substrate. Opt Mater Express, 2013, 3: 35–46
15 Coldren L A. Diode Lasers and Photonic Integrated Circuits. Opt Eng, 1997, 36: 616
16 Linghan L, Higo A, Higurashi E, et al. SOI platform and III-V integrated active photonic device by direct bonding for data communication. In: Proceedings of Low Temperature Bonding for 3D Integration. New York: IEEE, 2012
17 Park H, Fang A W, Cohen O, et al. A hybrid AlGaInAs-silicon evanescent amplifier. IEEE Photon Technol Lett, 2007, 19: 230–232
18 Cheung S, Kawakita Y, Shang K, et al. Theory and design optimization of energy-efficient hydrophobic wafer-bonded III-V/Si hybrid semiconductor optical amplifiers. J Lightw Technol, 2013, 31: 4057–4066
19 Kaspar P, de Valicourt G, Brenot R, et al. Hybrid III-V/silicon SOA in optical network based on advanced modulation formats. IEEE Photon Technol Lett, 2015, 27: 2383–2386
20 Mears R J, Reekie L, Jauncey I M, et al. Low-noise erbium-doped fibre amplifier operating at 1.54 μm. Electron Lett, 1987, 23: 1026–1028
21 Bradley J D, Pollnau M. Erbium-doped integrated waveguide amplifiers and lasers. Laser Photon Rev, 2011, 5: 368–403
22 Polman A. Erbium implanted thin film photonic materials. J Appl Phys, 1997, 82: 1–39
23 Kenyon A J. Recent developments in rare-earth doped materials for optoelectronics. Prog Quantum Electron, 2002, 26: 225–284
24 Zimmerman D R, Spiekman L H. Amplifiers for the masses: EDFA, EDWA, and SOA amplets for metro and access applications. J Lightw Technol, 2004, 22: 63–70
25 Brinkmann R, Baumann I, Dinand M, et al. Erbium-doped single- and double-pass Ti:LiNbO3 waveguide amplifiers. IEEE J Quantum Electron, 1994, 30: 2356–2360
26 Suche H, Baumann I, Hiller D, et al. Modelocked Er:Ti:LiNbO3-waveguide laser. Electron Lett, 1993, 29: 1111–1112
27 van den Hoven G N, Koper R J I M, Polman A, et al. Net optical gain at 1.53 μm in Er‐doped Al2O3 waveguides on silicon. Appl Phys Lett, 1996, 68: 1886–1888
28 Chryssou C E, Di Pasquale F, Pitt C W. Improved gain performance in Yb3+-sensitized Er3+-doped alumina (Al2O3) channel optical waveguide amplifiers. J Lightw Technol, 2001, 19: 345–349
29 Daldosso N, Pavesi L. Nanosilicon photonics. Laser Photon Rev, 2009, 3: 508–534
30 Barrios C A, Lipson M. Electrically driven silicon resonant light emitting device based on slot-waveguide. Opt Express, 2005, 13: 10092–10101
31 Yin Y, Sun K, Xu W J, et al. 1.53 μm photo- and electroluminescence from Er3+ in erbium silicate. J Phys-Condens Matter, 2009, 21: 012204
32 Wang B, Guo R M, Wang X J, et al. Near-infrared electroluminescence in ErYb silicate based light-emitting device. Opt Mater, 2012, 34: 1371–1374
33 Nykolak G, Haner M, Becker P C, et al. Systems evaluation of an Er3+-doped planar waveguide amplifier. IEEE Photon Technol Lett, 1993, 5: 1185–1187
34 Wang X J, Nakajima T, Isshiki H, et al. Fabrication and characterization of Er silicates on SiO2/Si substrates. Appl Phys Lett, 2009, 95: 041906
35 Strohhofer C, Polman A. Silver as a sensitizer for erbium. Appl Phys Lett, 2002, 81: 1414–1416
36 Strohh?fer C, Kik P G, Polman A. Selective modification of the Er3+4I11/2 branching ratio by energy transfer to Eu3+. J Appl Phys, 2000, 88: 4486–4490
37 van den Hoven G N, Snoeks E, Polman A, et al. Photoluminescence characterization of Er‐implanted Al2O3 films. Appl Phys Lett, 1993, 62: 3065–3067
38 Han H S, Seo S Y, Shin J H, et al. Coefficient determination related to optical gain in erbium-doped silicon-rich silicon oxide waveguide amplifier. Appl Phys Lett, 2002, 81: 3720–3722 127301-18
39 Isshiki H, de Dood M J A, Polman A, et al. Self-assembled infrared-luminescent Er-Si-O crystallites on silicon. Appl Phys Lett, 2004, 85: 4343–4345
40 Wang X J, Wang B, Wang L, et al. Extraordinary infrared photoluminescence efficiency of Er0.1Yb1.9SiO5 films on SiO2/Si substrates. Appl Phys Lett, 2011, 98: 071903
41 Guo R, Wang X, Zang K, et al. Optical amplification in Er/Yb silicate strip loaded waveguide. Appl Phys Lett, 2011, 99: 161115
42 Guo R, Wang B, Wang X, et al. Optical amplification in Er/Yb silicate slot waveguide. Opt Lett, 2012, 37: 1427
43 Wang L, Guo R M, Wang B, et al. Hybrid silicate waveguides for amplifier application. IEEE Photon Technol Lett, 2012, 24: 900–902
44 Wang X, Zhuang X, Yang S, et al. High gain submicrometer optical amplifier at near-infrared communication band. Phys Rev Lett, 2015, 115: 027403
45 Shu H W, Su Z T, Wang X J, et al. Recent progress of silicon photonics for middle-infrared application (in Chinese). Telecommun Sci, 2015, 31: 2015274 [舒浩文, 苏昭棠, 王兴军, 等. 面向中红外应用的硅基光电子学最近研究进展. 电信科学, 2015, 31: 2015274]
46 Ye R, Xu C, Wang X, et al. Room-temperature near-infrared up-conversion lasing in single-crystal Er-Y chloride silicate nanowires. Sci Rep, 2016, 6: 34407
47 Liu J, Sun X, Pan D, et al. Tensile-strained, n-type Ge as a gain medium for monolithic laser integration on Si. Opt Express, 2007, 15: 11272–11277
48 Liu J, Sun X, Camacho-Aguilera R, et al. Ge-on-Si laser operating at room temperature. Opt Lett, 2010, 35: 679–681
49 Claps R, Dimitropoulos D, Raghunathan V, et al. Observation of stimulated Raman amplification in silicon waveguides. Opt Express, 2003, 11: 1731–1739
50 Eichhorn M, Pollnau M. Spectroscopic Foundations of Lasers: Spontaneous Emission Into a Resonator Mode. IEEE J Select Topics Quantum Electron, 2015, 21: 486–501
51 Patel F D, Dicarolis S, Lum P, et al. A compact high-performance optical waveguide amplifier. IEEE Photon Technol Lett, 2004, 16: 2607–2609
52 Pollnau M. Rare-earth-ion-doped waveguide lasers on a silicon chip. In: Proceedings of SPIE 9359, Optical Components and Materials XII. San Francisco: SPIE, 2015. 935910
53 Bradley J D B, Costa e Silva M, Gay M, et al. 170 Gbit/s transmission in an erbium-doped waveguide amplifier on silicon. Opt Express, 2009, 17: 22201–22208
54 Zhou X, Yu J J, Huang M F, et al. Transmission of 32-Tb/s capacity over 580 km using RZ-shaped PDM-8QAM modulation format and cascaded multimodulus blind equalization algorithm. J Lightw Tech, 2010, 28: 456–465
55 Soulard R, Zinoviev A, Doualan J L, et al. Detailed characterization of pump-induced refractive index changes observed in Nd:YVO4, Nd:GdVO4 and Nd:KGW. Opt Express, 2010, 18: 1553–1568
56 Blaize S, Bastard L, Cassagnetes C, et al. Multiwavelengths DFB waveguide laser arrays in Yb-Er codoped phosphate glass substrate. IEEE Photon Technol Lett, 2003, 15: 516–518
57 Seufert J, Fischer M, Legge M, et al. DFB laser diodes in the wavelength range from 760 nm to 2.5 μm. Spectrochim Acta Part A-Mol Biomol Spectr, 2004, 60: 3243–3247
2 Wang X J, Su Z T, Zhou Z P. Recent progress of silicon photonics (in Chinese). Sci Sin-Phys Mech Astron, 2015, 45: 014201 [王兴军, 苏昭棠, 周治平. 硅基光电子学的最新进展. 中国科学: 物理学力学天文学, 2015, 45: 014201]
3 Mason B, Barton J, Fish G A, et al. Design of sampled grating DBR lasers with integrated semiconductor optical amplifiers. IEEE Photon Technol Lett, 2000, 12: 762–764
4 Murthy S, Kato M, Nagarajan R, et al. Large-scale photonic integrated circuit transmitters with monolithically integrated semiconductor optical amplifiers. In: Proceedings of Optical Fiber Communication/National Fiber Optic Engineers Conference. New York: IEEE Press, 2008
5 Nagarajan R, Kato M, Hurtt S, et al. Monolithic, 10 and 40 channel InP receiver photonic integrated circuits with on-chip amplification. In: Proceedings of Optical Fiber Communication Conference. Anaheim: Optical Society of America Press, 2007. PDP32
6 Durhuus T, Mikkelsen B, Joergensen C, et al. All-optical wavelength conversion by semiconductor optical amplifiers. J Lightw Technol, 1996, 14: 942–954
7 Dutta N K, Wang Q. Semiconductor Optical Amplifiers. Singapore: World Scientific, 2006
8 Davenport M L, Skendzic S, Volet N, et al. Heterogeneous Silicon/III-V Semiconductor Optical Amplifiers. IEEE J Select Topics Quantum Electron, 2016, 22: 78–88
9 Wang H C, Huang L R, Shi Z W. Amplified spontaneous emission spectrum and gain characteristic of a two-electrode semiconductor optical amplifier. J Semicond, 2011, 32: 064010
10 Duan G H, Jany C, Le Liepvre A, et al. Hybrid III-V on silicon lasers for photonic integrated circuits on silicon. IEEE J Sel Top Quantum Electron, 2014, 20: 90020X
11 Hawkins A R, Wu W, Abraham P, et al. High gain-bandwidth-product silicon heterointerface photodetector. Appl Phys Lett, 1997, 70: 303–305
12 Liang D, Chapman D C, Li Y, et al. Uniformity study of wafer-scale InP-to-silicon hybrid integration. Appl Phys A, 2011, 103: 213–218
13 Adler F, Moutzouris K, Leitenstorfer A, et al. Phase-locked two-branch erbium-doped fiber laser system for long-term precision measurements of optical frequencies. Opt Express, 2004, 12: 5872–5880
14 Keyvaninia S, Muneeb M, Stankovi? S, et al. Ultra-thin DVS-BCB adhesive bonding of III-V wafers, dies and multiple dies to a patterned silicon-on-insulator substrate. Opt Mater Express, 2013, 3: 35–46
15 Coldren L A. Diode Lasers and Photonic Integrated Circuits. Opt Eng, 1997, 36: 616
16 Linghan L, Higo A, Higurashi E, et al. SOI platform and III-V integrated active photonic device by direct bonding for data communication. In: Proceedings of Low Temperature Bonding for 3D Integration. New York: IEEE, 2012
17 Park H, Fang A W, Cohen O, et al. A hybrid AlGaInAs-silicon evanescent amplifier. IEEE Photon Technol Lett, 2007, 19: 230–232
18 Cheung S, Kawakita Y, Shang K, et al. Theory and design optimization of energy-efficient hydrophobic wafer-bonded III-V/Si hybrid semiconductor optical amplifiers. J Lightw Technol, 2013, 31: 4057–4066
19 Kaspar P, de Valicourt G, Brenot R, et al. Hybrid III-V/silicon SOA in optical network based on advanced modulation formats. IEEE Photon Technol Lett, 2015, 27: 2383–2386
20 Mears R J, Reekie L, Jauncey I M, et al. Low-noise erbium-doped fibre amplifier operating at 1.54 μm. Electron Lett, 1987, 23: 1026–1028
21 Bradley J D, Pollnau M. Erbium-doped integrated waveguide amplifiers and lasers. Laser Photon Rev, 2011, 5: 368–403
22 Polman A. Erbium implanted thin film photonic materials. J Appl Phys, 1997, 82: 1–39
23 Kenyon A J. Recent developments in rare-earth doped materials for optoelectronics. Prog Quantum Electron, 2002, 26: 225–284
24 Zimmerman D R, Spiekman L H. Amplifiers for the masses: EDFA, EDWA, and SOA amplets for metro and access applications. J Lightw Technol, 2004, 22: 63–70
25 Brinkmann R, Baumann I, Dinand M, et al. Erbium-doped single- and double-pass Ti:LiNbO3 waveguide amplifiers. IEEE J Quantum Electron, 1994, 30: 2356–2360
26 Suche H, Baumann I, Hiller D, et al. Modelocked Er:Ti:LiNbO3-waveguide laser. Electron Lett, 1993, 29: 1111–1112
27 van den Hoven G N, Koper R J I M, Polman A, et al. Net optical gain at 1.53 μm in Er‐doped Al2O3 waveguides on silicon. Appl Phys Lett, 1996, 68: 1886–1888
28 Chryssou C E, Di Pasquale F, Pitt C W. Improved gain performance in Yb3+-sensitized Er3+-doped alumina (Al2O3) channel optical waveguide amplifiers. J Lightw Technol, 2001, 19: 345–349
29 Daldosso N, Pavesi L. Nanosilicon photonics. Laser Photon Rev, 2009, 3: 508–534
30 Barrios C A, Lipson M. Electrically driven silicon resonant light emitting device based on slot-waveguide. Opt Express, 2005, 13: 10092–10101
31 Yin Y, Sun K, Xu W J, et al. 1.53 μm photo- and electroluminescence from Er3+ in erbium silicate. J Phys-Condens Matter, 2009, 21: 012204
32 Wang B, Guo R M, Wang X J, et al. Near-infrared electroluminescence in ErYb silicate based light-emitting device. Opt Mater, 2012, 34: 1371–1374
33 Nykolak G, Haner M, Becker P C, et al. Systems evaluation of an Er3+-doped planar waveguide amplifier. IEEE Photon Technol Lett, 1993, 5: 1185–1187
34 Wang X J, Nakajima T, Isshiki H, et al. Fabrication and characterization of Er silicates on SiO2/Si substrates. Appl Phys Lett, 2009, 95: 041906
35 Strohhofer C, Polman A. Silver as a sensitizer for erbium. Appl Phys Lett, 2002, 81: 1414–1416
36 Strohh?fer C, Kik P G, Polman A. Selective modification of the Er3+4I11/2 branching ratio by energy transfer to Eu3+. J Appl Phys, 2000, 88: 4486–4490
37 van den Hoven G N, Snoeks E, Polman A, et al. Photoluminescence characterization of Er‐implanted Al2O3 films. Appl Phys Lett, 1993, 62: 3065–3067
38 Han H S, Seo S Y, Shin J H, et al. Coefficient determination related to optical gain in erbium-doped silicon-rich silicon oxide waveguide amplifier. Appl Phys Lett, 2002, 81: 3720–3722 127301-18
39 Isshiki H, de Dood M J A, Polman A, et al. Self-assembled infrared-luminescent Er-Si-O crystallites on silicon. Appl Phys Lett, 2004, 85: 4343–4345
40 Wang X J, Wang B, Wang L, et al. Extraordinary infrared photoluminescence efficiency of Er0.1Yb1.9SiO5 films on SiO2/Si substrates. Appl Phys Lett, 2011, 98: 071903
41 Guo R, Wang X, Zang K, et al. Optical amplification in Er/Yb silicate strip loaded waveguide. Appl Phys Lett, 2011, 99: 161115
42 Guo R, Wang B, Wang X, et al. Optical amplification in Er/Yb silicate slot waveguide. Opt Lett, 2012, 37: 1427
43 Wang L, Guo R M, Wang B, et al. Hybrid silicate waveguides for amplifier application. IEEE Photon Technol Lett, 2012, 24: 900–902
44 Wang X, Zhuang X, Yang S, et al. High gain submicrometer optical amplifier at near-infrared communication band. Phys Rev Lett, 2015, 115: 027403
45 Shu H W, Su Z T, Wang X J, et al. Recent progress of silicon photonics for middle-infrared application (in Chinese). Telecommun Sci, 2015, 31: 2015274 [舒浩文, 苏昭棠, 王兴军, 等. 面向中红外应用的硅基光电子学最近研究进展. 电信科学, 2015, 31: 2015274]
46 Ye R, Xu C, Wang X, et al. Room-temperature near-infrared up-conversion lasing in single-crystal Er-Y chloride silicate nanowires. Sci Rep, 2016, 6: 34407
47 Liu J, Sun X, Pan D, et al. Tensile-strained, n-type Ge as a gain medium for monolithic laser integration on Si. Opt Express, 2007, 15: 11272–11277
48 Liu J, Sun X, Camacho-Aguilera R, et al. Ge-on-Si laser operating at room temperature. Opt Lett, 2010, 35: 679–681
49 Claps R, Dimitropoulos D, Raghunathan V, et al. Observation of stimulated Raman amplification in silicon waveguides. Opt Express, 2003, 11: 1731–1739
50 Eichhorn M, Pollnau M. Spectroscopic Foundations of Lasers: Spontaneous Emission Into a Resonator Mode. IEEE J Select Topics Quantum Electron, 2015, 21: 486–501
51 Patel F D, Dicarolis S, Lum P, et al. A compact high-performance optical waveguide amplifier. IEEE Photon Technol Lett, 2004, 16: 2607–2609
52 Pollnau M. Rare-earth-ion-doped waveguide lasers on a silicon chip. In: Proceedings of SPIE 9359, Optical Components and Materials XII. San Francisco: SPIE, 2015. 935910
53 Bradley J D B, Costa e Silva M, Gay M, et al. 170 Gbit/s transmission in an erbium-doped waveguide amplifier on silicon. Opt Express, 2009, 17: 22201–22208
54 Zhou X, Yu J J, Huang M F, et al. Transmission of 32-Tb/s capacity over 580 km using RZ-shaped PDM-8QAM modulation format and cascaded multimodulus blind equalization algorithm. J Lightw Tech, 2010, 28: 456–465
55 Soulard R, Zinoviev A, Doualan J L, et al. Detailed characterization of pump-induced refractive index changes observed in Nd:YVO4, Nd:GdVO4 and Nd:KGW. Opt Express, 2010, 18: 1553–1568
56 Blaize S, Bastard L, Cassagnetes C, et al. Multiwavelengths DFB waveguide laser arrays in Yb-Er codoped phosphate glass substrate. IEEE Photon Technol Lett, 2003, 15: 516–518
57 Seufert J, Fischer M, Legge M, et al. DFB laser diodes in the wavelength range from 760 nm to 2.5 μm. Spectrochim Acta Part A-Mol Biomol Spectr, 2004, 60: 3243–3247