复用信号放大过程动态行为的电路级研究
摘要
随着通信新业务的发展,语音、图像、数据等信息量呈现快速增长趋势,这对网络传输容量和传输距离等提出了更高的要求。波分复用(WDM)或副载波复用(SCM)与掺铒光纤放大器(EDFA)的结合应用是充分挖掘光纤带宽能力,实现大容量、长距离、高速率通信的有效手段,因此研究复用信号放大过程的动态行为有着重要的理论和实践意义。
本文以复用信号放大过程的物理方程为基础,不同于以往的处理方法,采用电子元件刻画基于受激辐射机制的光信号放大行为,并引入传输线宏模型表征掺铒光纤延迟的影响,在国内首次分别构建出波分复用信号放大和含啁啾效应的副载波复用信号放大的等效电路模型,将电路级仿真方法扩展到复用信号放大特性的研究中。
借助所构建的等效电路模型,利用电路仿真软件PSPICE,分别实施了直流、瞬态和交流输入信号情形下的动态仿真,模拟了WDM信号放大过程中通道数目对瞬态效应的影响、多通道放大输出功率谱以及信号间串话特性。并进一步对SCM信号放大情形进行了研究,分析了系统的互调失真(IM2)和输出功率谱特性。仿真结果表明,调整泵浦功率值可抑制瞬态效应,提高调制频率可使串话减弱,减小激光器的频率啁啾或增大EDFA的输入光功率都可改善IM2。这些分析与结果对实际系统的设计和优化有一定参考价值,也表明了基于等效电路模型的电路级仿真是研究光电系统相关问题的一种有效途径。
With the development of new communication services, the contents of information including voice, image and data increase quickly which bring a higher requirement for network's transmission capacity and distance. The technology of wavelength division multiplexing (WDM) system or subcarrier multiplexing (SCM) system combined with erbium-doped fiber amplifier (EDFA) is an effective method to realize high capacity, long haul, high speed communications, and can take fully advantage of the optical fiber's bandwidth. Therefore, studying on the dynamic behaviors of multiplexed signals in the amplification process has significant theoretical and practical meaning.In this paper, according to the basic physical equations of multiplexed signals in the amplification process, different from the traditional calculation methods, the electronic elements are adopted to describe the amplified behaviors of optical signals based on stimulated emission and the macro-model of transmission line is introduced to describe the time delay from the erbium-doped fiber. The equivalent circuit models of WDM signals and SCM signals including the chirping effect are established for the first time. Circuit-level simulation method is applied to investigate the amplified characteristics of multiplexed signals.Based on the equivalent circuit model, the dynamic simulations are implemented by performing the dc analysis, transient analysis and ac analysis through PSPICE. Typical characteristics are analyzed, including transient modulation, multi-channel output power spectrum and cross modulations of an eight-channel WDM. The intermodulation distortion and output power spectrum in an amplitude modulation SCM are demonstrated. The simulation results indicate that adjusting pump power properly can control transient effect, and increasing modulation frequency can weaken cross modulation, and decreasing frequency chirp of LD or enhancing the input power of signals can improve intermodulation distortion. These results will be useful for designing and optimizing the practical system and show that the method of circuit-level simulation based on circuit model is one of the effective methods in optoelectronic system simulations.
本文以复用信号放大过程的物理方程为基础,不同于以往的处理方法,采用电子元件刻画基于受激辐射机制的光信号放大行为,并引入传输线宏模型表征掺铒光纤延迟的影响,在国内首次分别构建出波分复用信号放大和含啁啾效应的副载波复用信号放大的等效电路模型,将电路级仿真方法扩展到复用信号放大特性的研究中。
借助所构建的等效电路模型,利用电路仿真软件PSPICE,分别实施了直流、瞬态和交流输入信号情形下的动态仿真,模拟了WDM信号放大过程中通道数目对瞬态效应的影响、多通道放大输出功率谱以及信号间串话特性。并进一步对SCM信号放大情形进行了研究,分析了系统的互调失真(IM2)和输出功率谱特性。仿真结果表明,调整泵浦功率值可抑制瞬态效应,提高调制频率可使串话减弱,减小激光器的频率啁啾或增大EDFA的输入光功率都可改善IM2。这些分析与结果对实际系统的设计和优化有一定参考价值,也表明了基于等效电路模型的电路级仿真是研究光电系统相关问题的一种有效途径。
With the development of new communication services, the contents of information including voice, image and data increase quickly which bring a higher requirement for network's transmission capacity and distance. The technology of wavelength division multiplexing (WDM) system or subcarrier multiplexing (SCM) system combined with erbium-doped fiber amplifier (EDFA) is an effective method to realize high capacity, long haul, high speed communications, and can take fully advantage of the optical fiber's bandwidth. Therefore, studying on the dynamic behaviors of multiplexed signals in the amplification process has significant theoretical and practical meaning.In this paper, according to the basic physical equations of multiplexed signals in the amplification process, different from the traditional calculation methods, the electronic elements are adopted to describe the amplified behaviors of optical signals based on stimulated emission and the macro-model of transmission line is introduced to describe the time delay from the erbium-doped fiber. The equivalent circuit models of WDM signals and SCM signals including the chirping effect are established for the first time. Circuit-level simulation method is applied to investigate the amplified characteristics of multiplexed signals.Based on the equivalent circuit model, the dynamic simulations are implemented by performing the dc analysis, transient analysis and ac analysis through PSPICE. Typical characteristics are analyzed, including transient modulation, multi-channel output power spectrum and cross modulations of an eight-channel WDM. The intermodulation distortion and output power spectrum in an amplitude modulation SCM are demonstrated. The simulation results indicate that adjusting pump power properly can control transient effect, and increasing modulation frequency can weaken cross modulation, and decreasing frequency chirp of LD or enhancing the input power of signals can improve intermodulation distortion. These results will be useful for designing and optimizing the practical system and show that the method of circuit-level simulation based on circuit model is one of the effective methods in optoelectronic system simulations.
引文
1 G. Keiser. Optical fiber communication, 3nd ed. BeiJing: Publishing House of Electronics Industry, 2002
2 A. A. M. Saleh, R. M. Jopson, J. D. Evenkow, et al. Modeling of gain in erbium-doped fiber amplifiers. IEEE J. Photonics Technology Letters. 1990, 2(10): 714-717
3 X. Zhang, A. Mitchell. A simple black box model for erbium-doped fiber amplifiers. IEEE J. Photonics Technology Letters. 2000, 12(1): 28-30
4 M. Yamada, H. Ono, T. Kanamori, et al. A low-noise and gain-flattened amplifier composed of a silica-based and a fluoride-based Er~(3+)-doped fiber amplifier in a cascade configuration. IEEE J. Photonics Technology Letters. 1996, 8(5): 620-622
5 K. Inoue, T. Kominato, H. Toba. Tunable gain equalization using a Mach-Zehnder optical filter in multistage fiber amplifier. IEEE J. Photonics Technology. Letters. 1991, 3(8): 718-720
6 J. Burgmeier, A. Cords, R. Marz, et al. A black box model of EDFA's operating in WDM systems. J. Lightwave Technology. 1998, 16(7): 1271-1275
7 A. E. Willner, S. M. Hwan. Transmission of many WDM channels through a cascade of EDFA's in long-distance links and ring networks. J. Lightwave Technology. 1995, 13(5): 802-816
8 S. Shikii, A. Sasaki, M. Suzuki, et al. EDFA for SCM transliaission systems. Lasers and Electro-Optics Society 1996, 2(11): 404-405
9 K. Rottwitt, A. Bjarklev, J. H. Povlsen, et al. Fundamental design of a distributed erbium-doped fiber amplifier for long-distance transmission. J. Lightwave Technology. 1992, 10(11): 1544-1552
10 C. K. Liu, J. J. Jou, F. S. Lai. Second-order harmonic distortion and optimal fiber length in erbium-doped fiber amplifiers. IEEE J. Photonics Technology Letters. 1995, 7(12): 1412-1414
11 Y. Sun, A. A. M. Saleh, J. L. Zyshind, et al. Modeling of small-signal cross-modulation in WDM optical systems with erbium-doped fiber amplifiers. Optical Fiber Communication 1997: 106-107
12 J. Ohya, H. Sato, M. Mitsuda, et al. Second-order distortion of amplified intensity-modulated signals with chii-ping in erbium-doped fiber. J. Lightwave Technology. 1995, 13(11): 2129-2135
13 Y. Sun, A. A. M. Saleh, J. L. Zyskind, et al. Time dependent perturbation theory and tones in cascaded erbium-doped fiber amplifier systems. J. Lightwave Technology. 1997, 15(7): 1083-1087
14 F. S. Lai, C. K. Liu, J.-J. Jou. Analyses of distortions and cross modulations in erbium-doped fiber amplifiers. IEEE J. Photonics Technology Letters. 1999, 11(5): 545-547
15 潘炜,张晓霞,罗斌,等.铁电液晶显示器记忆特性的Pspice可视化分析.光电子·激光.2002,13(6):571-574
16 潘炜,张晓霞,罗斌,等.铁电液晶光电响应特性的电路级模拟.电子学报.2002,30(5):708-710
17 R. S. Tucker, D. J. Pope. Microwave circuit models of semiconductor injection lasers. IEEE Tran. Microwave Theory and Techniques, 1983, 31(3): 289-294
18 李诺晗,潘炜,罗斌.VCSOA典型参数特性的电路级分析.固体电子学研究与进展.2004,24(2):233-237
19 Y. M. El-Batawy, M. J. Deen, N. R. Das. Analysis, optimization, and SPICE modeling of resonant cavity enhanced p-i-n photodetector. J. Lightwave Technology. 2003, 21(9): 2031-2043
20 S. W. Lee, E. C. Choi, W. Y. Choi. Optical interconnection system analysis using SPICE. Lasers and Electro-Optics 1999, 2(30): 391-392
21 A. Bononi, L. A. Rusch, L. Tancevski. Simple dynamic model of fiber amplifiers and equivalent electrical circuit. J. Electronics Letters. 1997, 33(22): 1887-1888
22 C. K. Liu, J. J. Jou, S. K. Liaw. Computer-aided analysis of transients in fiber lasers and gain-clamped fiber amplifiers in ring and line configurations through a circuit simulator. J. Optics Communication, 2002, 209(4-6): 427-436
23 J. J. Jou, C. K. Liu. Application of SPICE simulation to study WDM and SCM systems using EDFAs with chirping. IEEE Tran. on education. 2002, 45(3): 238-244
24 陈维友,杨树人,刘式墉.光电子器件模型与OEIC模拟.北京:国防工业出版社,2001
25 高燕梅,房蔓楠.Spice/Pspice编程技术.北京:电子工业出版社,2002
26 G. P. Agrawal. Nonlinear fiber optics & Applications of nonlinear fiber optics. BeiJing: Publishing House of Electronics Industry, 2002: 373-380
27 强则煊.低噪声、高增益、高平坦度掺铒光纤放大器的分析与实验研究.浙江大学博士论文.2004:14-20
28 G. P. Agrawal, N. K. Dutta. Semiconductor Lasers. 2nd edition. New York: Van Nostran Reinhold, 1993
29 A. W. T. Wu, A. J. Lowery. Efficient multiwavelength dynamic model for erbium-doped fiber amplifier. IEEE J. Qunantum Electronics. 1998, 34(8): 1325-1331
30 A. K. Srivastava, Y. Sun, J. L. Zyskind, et al. EDFA transient response to channel loss in WDM transmission system. IEEE J. Photonics Technology Letters. 1997, 9(3): 386-388
31 H. H. Lee, D. Lee, H. S. Chung, et al. Effective suppression of signal-wavelength transients in a pump-controlled L-band EDFA. Optical Fiber Communication 2004: 3-5
32 H. Ono, K. Shimano, M. Fukutoku, et al. An EDFA gain control and power monitoring scheme for fault detection in WDM networks by employing a power-stabilized control channel. J. Lightwave Technology. 2002, 20(8): 1335-1341
33 C. Tian, S, Kinoshita. Analysis and control of transient dynamics of EDFA pumped by 1480- and 980-nm lasers. J. Lightwave Technology. 2003, 21(8): 1728-1734
34 S. Y. Kim, J. Chung, B. Lee. Dynamic performance of the all-optical gain controlled EDFA cascade in multiwavelength optical networks. J. Electronics Letters. 1997, 33(17): 1475-1477
35 M. Karasek, F. W. Willems. Channel addition/removal response in cascades of strongly inverted erbium-doped fiber amplifiers. J. Lightwave Technology. 1998, 16(12):2311-2317
36 E. L. Goldstein, L. Eskildsen, C. Lin, et al. Multiwavelength propagation in lightwave systems with strongly inverted fiber amplifiers. IEEE J. Photonics Technology Letters. 1994, 6(2):266-269
37 J. Bryce, G Yoffe, Y. Zhao, et al. Tunable, gain-clamped EDFA incorporating chirped fibre Bragg grating. J. Electronics Letters. 1998,34(17): 1680-1681
38 P. F. Wysocki, J. B. Judkins, R. P. Espindola, et al. Broad-band erbium-doped fiber amplifier flattened beyond 40nm using long-period grating filter. IEEE J. Photonics Technology Letters. 1998, 9(10): 1343-1345
39 S. H. Huang, X. Y. Zou, E A. E. Willner, et al. Experimental demonstration of active equalization and ASE suppression of three 2.5-Gb/s WDM-network channels over 2500km using AOTF as transmission filters. IEEE J. Photonics Technology Letters. 1997, 9(3):389-391
40 K. E. Alameh, R. A. Minasian. Optimization of fiber amplifier SCM lightwave video systems using direct and external modulation. J. Lightwave Technology. 1993,11(1):76-81
41 K. Kikushima. Using equalizers to offset the deterioration in SCM video transmission due to fiber dispersion and EDFA gain tilt. J. Lightwave Technology. 1992,10(10):1443-1449
42 H. Sasai, M. Fuse, K. Utsumi, et al. Required performance for optical filter and EDFA in 32ch-WDM/310ch-SCM transmission system. Optoelectronics and Communications 1999, l(10):420-423
43 E. Yoneda, K. I. Suto, K. Kikushima, et al. All-fiber video distribution (AFVD) systems using SCM and EDFA techniques. J. Lightwave Technology. 1993,
44 A. A. M. Saleh. Fundamental limit on number of channels in subcarrier-multiplexed lightwave CATV system. J. Electronics Letters. 1989,25(6):776-777
45 C. Y. Kuo. Fundamental nonlinear distortions in analog links with fiber amplifiers. J. Lightwave Technology. 1993,11(1):7-15
46 B. Clesca, P. Bousselet, L. Hamon. Second-order distortion improvements or degradations brought by erbium-doped fiber amplifiers in analog links using
2 A. A. M. Saleh, R. M. Jopson, J. D. Evenkow, et al. Modeling of gain in erbium-doped fiber amplifiers. IEEE J. Photonics Technology Letters. 1990, 2(10): 714-717
3 X. Zhang, A. Mitchell. A simple black box model for erbium-doped fiber amplifiers. IEEE J. Photonics Technology Letters. 2000, 12(1): 28-30
4 M. Yamada, H. Ono, T. Kanamori, et al. A low-noise and gain-flattened amplifier composed of a silica-based and a fluoride-based Er~(3+)-doped fiber amplifier in a cascade configuration. IEEE J. Photonics Technology Letters. 1996, 8(5): 620-622
5 K. Inoue, T. Kominato, H. Toba. Tunable gain equalization using a Mach-Zehnder optical filter in multistage fiber amplifier. IEEE J. Photonics Technology. Letters. 1991, 3(8): 718-720
6 J. Burgmeier, A. Cords, R. Marz, et al. A black box model of EDFA's operating in WDM systems. J. Lightwave Technology. 1998, 16(7): 1271-1275
7 A. E. Willner, S. M. Hwan. Transmission of many WDM channels through a cascade of EDFA's in long-distance links and ring networks. J. Lightwave Technology. 1995, 13(5): 802-816
8 S. Shikii, A. Sasaki, M. Suzuki, et al. EDFA for SCM transliaission systems. Lasers and Electro-Optics Society 1996, 2(11): 404-405
9 K. Rottwitt, A. Bjarklev, J. H. Povlsen, et al. Fundamental design of a distributed erbium-doped fiber amplifier for long-distance transmission. J. Lightwave Technology. 1992, 10(11): 1544-1552
10 C. K. Liu, J. J. Jou, F. S. Lai. Second-order harmonic distortion and optimal fiber length in erbium-doped fiber amplifiers. IEEE J. Photonics Technology Letters. 1995, 7(12): 1412-1414
11 Y. Sun, A. A. M. Saleh, J. L. Zyshind, et al. Modeling of small-signal cross-modulation in WDM optical systems with erbium-doped fiber amplifiers. Optical Fiber Communication 1997: 106-107
12 J. Ohya, H. Sato, M. Mitsuda, et al. Second-order distortion of amplified intensity-modulated signals with chii-ping in erbium-doped fiber. J. Lightwave Technology. 1995, 13(11): 2129-2135
13 Y. Sun, A. A. M. Saleh, J. L. Zyskind, et al. Time dependent perturbation theory and tones in cascaded erbium-doped fiber amplifier systems. J. Lightwave Technology. 1997, 15(7): 1083-1087
14 F. S. Lai, C. K. Liu, J.-J. Jou. Analyses of distortions and cross modulations in erbium-doped fiber amplifiers. IEEE J. Photonics Technology Letters. 1999, 11(5): 545-547
15 潘炜,张晓霞,罗斌,等.铁电液晶显示器记忆特性的Pspice可视化分析.光电子·激光.2002,13(6):571-574
16 潘炜,张晓霞,罗斌,等.铁电液晶光电响应特性的电路级模拟.电子学报.2002,30(5):708-710
17 R. S. Tucker, D. J. Pope. Microwave circuit models of semiconductor injection lasers. IEEE Tran. Microwave Theory and Techniques, 1983, 31(3): 289-294
18 李诺晗,潘炜,罗斌.VCSOA典型参数特性的电路级分析.固体电子学研究与进展.2004,24(2):233-237
19 Y. M. El-Batawy, M. J. Deen, N. R. Das. Analysis, optimization, and SPICE modeling of resonant cavity enhanced p-i-n photodetector. J. Lightwave Technology. 2003, 21(9): 2031-2043
20 S. W. Lee, E. C. Choi, W. Y. Choi. Optical interconnection system analysis using SPICE. Lasers and Electro-Optics 1999, 2(30): 391-392
21 A. Bononi, L. A. Rusch, L. Tancevski. Simple dynamic model of fiber amplifiers and equivalent electrical circuit. J. Electronics Letters. 1997, 33(22): 1887-1888
22 C. K. Liu, J. J. Jou, S. K. Liaw. Computer-aided analysis of transients in fiber lasers and gain-clamped fiber amplifiers in ring and line configurations through a circuit simulator. J. Optics Communication, 2002, 209(4-6): 427-436
23 J. J. Jou, C. K. Liu. Application of SPICE simulation to study WDM and SCM systems using EDFAs with chirping. IEEE Tran. on education. 2002, 45(3): 238-244
24 陈维友,杨树人,刘式墉.光电子器件模型与OEIC模拟.北京:国防工业出版社,2001
25 高燕梅,房蔓楠.Spice/Pspice编程技术.北京:电子工业出版社,2002
26 G. P. Agrawal. Nonlinear fiber optics & Applications of nonlinear fiber optics. BeiJing: Publishing House of Electronics Industry, 2002: 373-380
27 强则煊.低噪声、高增益、高平坦度掺铒光纤放大器的分析与实验研究.浙江大学博士论文.2004:14-20
28 G. P. Agrawal, N. K. Dutta. Semiconductor Lasers. 2nd edition. New York: Van Nostran Reinhold, 1993
29 A. W. T. Wu, A. J. Lowery. Efficient multiwavelength dynamic model for erbium-doped fiber amplifier. IEEE J. Qunantum Electronics. 1998, 34(8): 1325-1331
30 A. K. Srivastava, Y. Sun, J. L. Zyskind, et al. EDFA transient response to channel loss in WDM transmission system. IEEE J. Photonics Technology Letters. 1997, 9(3): 386-388
31 H. H. Lee, D. Lee, H. S. Chung, et al. Effective suppression of signal-wavelength transients in a pump-controlled L-band EDFA. Optical Fiber Communication 2004: 3-5
32 H. Ono, K. Shimano, M. Fukutoku, et al. An EDFA gain control and power monitoring scheme for fault detection in WDM networks by employing a power-stabilized control channel. J. Lightwave Technology. 2002, 20(8): 1335-1341
33 C. Tian, S, Kinoshita. Analysis and control of transient dynamics of EDFA pumped by 1480- and 980-nm lasers. J. Lightwave Technology. 2003, 21(8): 1728-1734
34 S. Y. Kim, J. Chung, B. Lee. Dynamic performance of the all-optical gain controlled EDFA cascade in multiwavelength optical networks. J. Electronics Letters. 1997, 33(17): 1475-1477
35 M. Karasek, F. W. Willems. Channel addition/removal response in cascades of strongly inverted erbium-doped fiber amplifiers. J. Lightwave Technology. 1998, 16(12):2311-2317
36 E. L. Goldstein, L. Eskildsen, C. Lin, et al. Multiwavelength propagation in lightwave systems with strongly inverted fiber amplifiers. IEEE J. Photonics Technology Letters. 1994, 6(2):266-269
37 J. Bryce, G Yoffe, Y. Zhao, et al. Tunable, gain-clamped EDFA incorporating chirped fibre Bragg grating. J. Electronics Letters. 1998,34(17): 1680-1681
38 P. F. Wysocki, J. B. Judkins, R. P. Espindola, et al. Broad-band erbium-doped fiber amplifier flattened beyond 40nm using long-period grating filter. IEEE J. Photonics Technology Letters. 1998, 9(10): 1343-1345
39 S. H. Huang, X. Y. Zou, E A. E. Willner, et al. Experimental demonstration of active equalization and ASE suppression of three 2.5-Gb/s WDM-network channels over 2500km using AOTF as transmission filters. IEEE J. Photonics Technology Letters. 1997, 9(3):389-391
40 K. E. Alameh, R. A. Minasian. Optimization of fiber amplifier SCM lightwave video systems using direct and external modulation. J. Lightwave Technology. 1993,11(1):76-81
41 K. Kikushima. Using equalizers to offset the deterioration in SCM video transmission due to fiber dispersion and EDFA gain tilt. J. Lightwave Technology. 1992,10(10):1443-1449
42 H. Sasai, M. Fuse, K. Utsumi, et al. Required performance for optical filter and EDFA in 32ch-WDM/310ch-SCM transmission system. Optoelectronics and Communications 1999, l(10):420-423
43 E. Yoneda, K. I. Suto, K. Kikushima, et al. All-fiber video distribution (AFVD) systems using SCM and EDFA techniques. J. Lightwave Technology. 1993,
44 A. A. M. Saleh. Fundamental limit on number of channels in subcarrier-multiplexed lightwave CATV system. J. Electronics Letters. 1989,25(6):776-777
45 C. Y. Kuo. Fundamental nonlinear distortions in analog links with fiber amplifiers. J. Lightwave Technology. 1993,11(1):7-15
46 B. Clesca, P. Bousselet, L. Hamon. Second-order distortion improvements or degradations brought by erbium-doped fiber amplifiers in analog links using