基于MEMS技术的波长选择开关研究
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摘要
随着光通信技术的发展,尤其是光密集波分复用(Dense WaveLength Division Multiplexing, DWDM)技术的广泛应用,光交叉连接技术(Optical Cross Connection, OXC)和可重构光分插复用技术( Reconfigurable Optical Add/Drop Multiplexer, ROADM)受到了越来越多的关注。波长选择开关(Wavelength Selective Switch,WSS)因具有对不同波长自由选取的功能而在以上两种技术中起到了十分重要的作用,已经成为目前国内外的研究热点。
论文介绍了几种典型的WSS结构,对它们的特点进行了分析和比较,在此基础上提出了一种基于微电机系统(Micro Electro Mechanical Systems, MEMS)技术的WSS研究方案。该方案分别以透射式相位光栅和MEMS微镜阵列作为色散元件和光路控制元件,二者分别位于一个分析透镜的前后焦面上,构成一个2f系统;以准直器阵列作为输入/输出端口,光束经过棱镜组扩束之后再入射在光栅上,以提高光栅分辨本领;为了缩小器件体积,以一个反射镜和一个转向棱镜对光路进行折叠。
利用波动光学的相关理论推导了基模高斯光束的耦合效率公式,继而得出通带宽度与MEMS微镜阵列的占空比和限制因子之间的关系。分析了光栅角色散、分析透镜焦距、信道间隔与MEMS微镜间距之间的关系;推导出了棱镜组的顶角、扩束比与光束入射角之间的关系;重点分析了高斯光场在光路中的变换与匹配问题,分析了光场失配造成的器件损耗。这些分析结果对于WSS的光学设计和光路调试都有着重要的指导意义。
基于以上分析结果,对各个元件进行参数设计和加工,制作了一个1×4端口的WSS器件,测试了器件性能,插入损耗<5.08dB,端口串扰<-45dB,偏振相关损耗<0.186dB。实验结果表明,所设计的WSS具有结构简单、扩展性好、插入损耗低等诸多优点。该器件作为构成ROADM和OXC的关键部件,可以提高光网络中网元节点的灵活性和稳定性。
With the development of optical communication, especially the wide applications of dense wavelength division multiplexing (DWDM) technology, technologies such as optical cross connection (OXC) and reconfigurable optical add/drop multiplexer (ROADM) are attracting more and more attention. Wavelength selective switch (WSS) is characterized by free switching of individual wavelength, which enables it as an important part in above two technologies and thus becames a global research focus in optical communication.
The present typical structures for a WSS were introduced and the respective characteristics were analyzed and compared. A new WSS structure based on MEMS (micro-electro-mechanical system) technology was presented. A transmitting phase grating and a MEMS mirror array were employed as the wavelength dispersiing and beam controlling elements respectively. The two elements were located on the front and rear focal plane of a resolution lens, which constructs a 2f optical system. An optical fiber collimator array was employed as the input/output ports. The optical beam is first expanded by a prism group and then incidents on the grating, thus the resolving power of the grating is improved. In order to reduce the WSS size, a mirror and a steering prism were employed to fold the optical path.
The formula to calculate the power-coupling efficiency of the fundamental-mode gaussian beam was developed based on wave optics theory, thus the passband under given mirror array parameters, such as filling ratio and beam confining factor, was obtained. The relationship among the angular dispersion of the grating, the focal length of the resolution lens, the channel spacing and the pitch of the MEMS mirror array was analyzed. The beam expanding ratio of the prism group was deduced under a given prism angle and beam incident angle. The transforming and matching of Gaussian field in the optical system were anslyzed in emphasis. The power loss resulting from mismatch of Gaussian field was studied. These analyses are most important for the WSS design and optical adjustment.
Based on above analyses, the elements for the WSS were designed and fabricated andd a 1×4 WSS was assembled. The device specifications were tested. The insertion loss is <5.08dB, the crosstalk between ports is <-45dB, the polarization dependent loss is <0.186dB. The results show that the designed WSS is characterized by simple structure, good scalibility and low loss. It can be employed as the key part in a ROADM and OXC, thus the flexibility and stability of network node is improved.
论文介绍了几种典型的WSS结构,对它们的特点进行了分析和比较,在此基础上提出了一种基于微电机系统(Micro Electro Mechanical Systems, MEMS)技术的WSS研究方案。该方案分别以透射式相位光栅和MEMS微镜阵列作为色散元件和光路控制元件,二者分别位于一个分析透镜的前后焦面上,构成一个2f系统;以准直器阵列作为输入/输出端口,光束经过棱镜组扩束之后再入射在光栅上,以提高光栅分辨本领;为了缩小器件体积,以一个反射镜和一个转向棱镜对光路进行折叠。
利用波动光学的相关理论推导了基模高斯光束的耦合效率公式,继而得出通带宽度与MEMS微镜阵列的占空比和限制因子之间的关系。分析了光栅角色散、分析透镜焦距、信道间隔与MEMS微镜间距之间的关系;推导出了棱镜组的顶角、扩束比与光束入射角之间的关系;重点分析了高斯光场在光路中的变换与匹配问题,分析了光场失配造成的器件损耗。这些分析结果对于WSS的光学设计和光路调试都有着重要的指导意义。
基于以上分析结果,对各个元件进行参数设计和加工,制作了一个1×4端口的WSS器件,测试了器件性能,插入损耗<5.08dB,端口串扰<-45dB,偏振相关损耗<0.186dB。实验结果表明,所设计的WSS具有结构简单、扩展性好、插入损耗低等诸多优点。该器件作为构成ROADM和OXC的关键部件,可以提高光网络中网元节点的灵活性和稳定性。
With the development of optical communication, especially the wide applications of dense wavelength division multiplexing (DWDM) technology, technologies such as optical cross connection (OXC) and reconfigurable optical add/drop multiplexer (ROADM) are attracting more and more attention. Wavelength selective switch (WSS) is characterized by free switching of individual wavelength, which enables it as an important part in above two technologies and thus becames a global research focus in optical communication.
The present typical structures for a WSS were introduced and the respective characteristics were analyzed and compared. A new WSS structure based on MEMS (micro-electro-mechanical system) technology was presented. A transmitting phase grating and a MEMS mirror array were employed as the wavelength dispersiing and beam controlling elements respectively. The two elements were located on the front and rear focal plane of a resolution lens, which constructs a 2f optical system. An optical fiber collimator array was employed as the input/output ports. The optical beam is first expanded by a prism group and then incidents on the grating, thus the resolving power of the grating is improved. In order to reduce the WSS size, a mirror and a steering prism were employed to fold the optical path.
The formula to calculate the power-coupling efficiency of the fundamental-mode gaussian beam was developed based on wave optics theory, thus the passband under given mirror array parameters, such as filling ratio and beam confining factor, was obtained. The relationship among the angular dispersion of the grating, the focal length of the resolution lens, the channel spacing and the pitch of the MEMS mirror array was analyzed. The beam expanding ratio of the prism group was deduced under a given prism angle and beam incident angle. The transforming and matching of Gaussian field in the optical system were anslyzed in emphasis. The power loss resulting from mismatch of Gaussian field was studied. These analyses are most important for the WSS design and optical adjustment.
Based on above analyses, the elements for the WSS were designed and fabricated andd a 1×4 WSS was assembled. The device specifications were tested. The insertion loss is <5.08dB, the crosstalk between ports is <-45dB, the polarization dependent loss is <0.186dB. The results show that the designed WSS is characterized by simple structure, good scalibility and low loss. It can be employed as the key part in a ROADM and OXC, thus the flexibility and stability of network node is improved.
引文
[1]张宝富.全光网络. (第1版).北京:人民邮电出版社, 2002. 2~8
[2] Thomas E.Stem著.多波长光网络. (第1版).徐荣、龚倩译.北京:人民邮电出版社, 2001. 1~14
[3] Richard A. Barry, Vincent W. S. Chan, Katherine L. Hall, et al. All-Optical Network Consortium Ultrafast TDM Networks. Journal on Selected Areas in Communications, 1996, 14(5): 999~1013
[4] Rhee J K, Tomkos I, Ming-Jun L. A broadcast-and-select OADM optical network with dedicated optical-channel protection. Lightwave Technology, 2003, 21(1):25-31
[5] Eldada L, Fujita J, Radojevic A, et al. 40-channel ultra-low-power compact PLC-based ROADM subsystem[A]. OFC2006
[6] Lei Zong, Xiaodong Huan, Ting Wang, et al. A Novel Tunable DeMUX/MUX Solution for WSS-Based ROADM and WXC Nodes. NFOEC, 2007. 1~7
[7] Doerr C. R, Stulz L. W, Levy D. S. Wavelength add-drop node using silica waveguide integration. J. Lightwave Technol, 2004, 12(22): 2755~2762
[8] Doerr C. R, Stulz L. W, Levy D. S. Silica-waveguide 1×9 wavelength- selective cross connect. OFC2002: FA3-1
[9] Ducellier T, Hnatiw A, Mala M. Novel high performance hybrid waveguide MEMS 1×9 wavelength selective switch in a 32-cascade loop experiment. ECOC2004: Th4.2.2
[10] Fondeur B. Crafts D. E., and Ranalli E. Planar lightwave circuit based wavelength selective switch. United States Patent 0,031,570A1, 2008
[11] Doerr C.R., Marom D.M. Wavelength-selective switch and integrated wavelength demultiplexer using stacked planar lightwave circuits. United States Patent 0,198,575A1, 2006
[12]李新碗.波长选择光开关与突发交换系统关键技术研究: [博士学位论文].上海:上海交通大学图书馆, 2005
[13]申中华,李勇.一种基于MEMS光开关的波长选择开关的设计方法.中国通信学会第五届学术年会论文集. 2008
[14]许端,谢卉,胡强高等.基于液晶技术的1×2 WSS的设计和实验.光通信研究,2008, 6: 40~42
[15]胡强高,孙莉萍,施伟等.具有无干扰切换的波长选择开关.中国,国家发明专利,专利公开号: CN 201194034, 2009. 1~5
[16]胡强高,刘德明,张玓.一种基于微机电系统技术的新型波长选择开关.光学学报, 2010, 30(4): 1168~1172
[17] B.C.Collings. Wavelength Selectable Switches and Future Photonic Network Applications. 2008 International Conference on Photonics in Switching. 2008, 1~4
[18] Pierre Wall, Paul Colbourne, Christopher Reimer, et al. WSS Switching Engine Technologies. Conference on OFC/NFOEC’08, 2008. 1~5
[19]许端.波长选择开关的实现技术分析.中国高校通信类院系学术研讨会论文集(下册), 2009. 445~448
[20]许端,谢卉,胡强高等.基于液晶技术的1×2 WSS的设计和实验.光通信研究, 2008, 150(6): 40~42
[21] Glenn Baxter, Steven Frisken, Dmitri Abakoumov, et al., Highly programmable Wavelength Selective Switch based on Liquid Crystal on Silicon switching elements. Proc OFC/ NFOEC, 2006. 1~3
[22] D.M.Marom, David.T.Neilson, Dennis.S.Greywall, et al. Wavelength-Selective 1×K Switches Using Free Space Optics and MEMS Micromirrors: Theory, Design and Implementation. J.Lightwave Tech., 2005, 23(4): 1620~1630
[23] Jui-che Tsai, Ming C.Wu. Design, Fabrication, and Characterization of a High Fill Factor, Large Scan-Angle,Two-Axis Scanner Array Driven by a Leverage Mechanism. Journal of Microelectromechanical Systems, 2006, 15(5):1209~1213
[24]马志波. MEMS微变形镜测试及工艺防粘附技术研究: [硕士学位论文].西安:西北工业大学图书馆, 2007
[25] Capella光子学公司.减少MEMS微镜边缘衍射的方法.美国,国家发明专利,专利公开号: CN 101384933A, 2009. 1~2
[26]郁道银,谈恒英.工程光学. (第1版).北京:机械工业出版社, 1994. 267~268
[27]陈洪璆,王杰波,曹向群.离子刻蚀矩形位相光栅衍射特性研究.中国光学学会2004年学术大会论文集, 2004. 50~54
[28]刘全,吴建宏.光栅的标量衍射理论与耦合波理论的分析比较.激光杂志, 2004, 25(2): 31~33
[29]樊叔维.二元光栅衍射特性的矢量理论分析.光学精密工程, 1999, 7(5): 30~36
[30]王鹏,徐毓光,余勤跃等.矩形光栅的衍射特性.光子学报, 1999, 28(5): 446~450
[31] M. G. Moharam, Eric B. Grann, and Drew A. Pommet. Formulation for stable and efficient implementation oft he rigorous coupled-wave analysis of binary gratings. J.Opt.Soc.Am. 1995, 12(5): 1068~1076
[32]郑辉.闪耀光栅对厄米—高斯光束的衍射.中国激光, 1982, 10(1): 1~7
[33]赵继德,李应良.全光网络中的MEMS光开关.激光杂志, 2005, 26(3): 10~12
[34]柯昌剑,刘德明.球透镜准直器耦合效率的研究.中国激光, 2002, 6(A29): 371~374
[35]王素芹,阮玉,殷东亮. C-lens准直器回波损耗的理论计算与分析.光电子技术与信息, 2003, 16(1): 24~28
[36]陈海清,曹向英.光盘光学头整形棱镜光学系统的设计.光电工程, 1997, 24(1): 21~25
[37]陈清海.消色差棱镜扩束器.激光与红外, 1987, 7(1): 30~33
[38]刘鈞,高明编.光学设计. (第1版).西安:西安电子科技大学出版社, 2006. 244~ 259
[39] David C.Hanna. Astigmatic Gaussian Beams Produced by Axially Asymmetric Laser Cavities. Journal of Quantum Electronics, 1969, 5(10):483~488
[40]沈学举,郭晓维.三棱镜对圆高斯光束的变换.光学技术, 1999, 1(4): 63~67
[41]赵道木,林强,王绍民.运用张量ABCD定律分析简单象散高斯光束的对称化.杭州大学学报, 1994, 21(1): 36~40
[42] Shifu Yuan, Nabeel A.Riza. General formula for coupling-loss characterization of single-mode fiber collimators by use of gradient-index rod lenses. Applied Optics, 1999, 38(15): 3214~3222
[43]林学煌.光无源器件. (第1版).北京:人民邮电出版社, 1998. 183~187
[44]杨四刚,潘晴,胡必春.基于固体腔F-P标准具的可调谐自适应光滤波器.半导体光电, 2003, 24(2): 107~134
[45] Renzhong Hua, Satoshi Wada, Hideo Tashiro. Principles and limitations of a quarter-wave plate for reducing the depolarization loss from thermally induced birefringence in Nd:YAG lasers. Optics Communications, 2000, 175(1):189~200
[2] Thomas E.Stem著.多波长光网络. (第1版).徐荣、龚倩译.北京:人民邮电出版社, 2001. 1~14
[3] Richard A. Barry, Vincent W. S. Chan, Katherine L. Hall, et al. All-Optical Network Consortium Ultrafast TDM Networks. Journal on Selected Areas in Communications, 1996, 14(5): 999~1013
[4] Rhee J K, Tomkos I, Ming-Jun L. A broadcast-and-select OADM optical network with dedicated optical-channel protection. Lightwave Technology, 2003, 21(1):25-31
[5] Eldada L, Fujita J, Radojevic A, et al. 40-channel ultra-low-power compact PLC-based ROADM subsystem[A]. OFC2006
[6] Lei Zong, Xiaodong Huan, Ting Wang, et al. A Novel Tunable DeMUX/MUX Solution for WSS-Based ROADM and WXC Nodes. NFOEC, 2007. 1~7
[7] Doerr C. R, Stulz L. W, Levy D. S. Wavelength add-drop node using silica waveguide integration. J. Lightwave Technol, 2004, 12(22): 2755~2762
[8] Doerr C. R, Stulz L. W, Levy D. S. Silica-waveguide 1×9 wavelength- selective cross connect. OFC2002: FA3-1
[9] Ducellier T, Hnatiw A, Mala M. Novel high performance hybrid waveguide MEMS 1×9 wavelength selective switch in a 32-cascade loop experiment. ECOC2004: Th4.2.2
[10] Fondeur B. Crafts D. E., and Ranalli E. Planar lightwave circuit based wavelength selective switch. United States Patent 0,031,570A1, 2008
[11] Doerr C.R., Marom D.M. Wavelength-selective switch and integrated wavelength demultiplexer using stacked planar lightwave circuits. United States Patent 0,198,575A1, 2006
[12]李新碗.波长选择光开关与突发交换系统关键技术研究: [博士学位论文].上海:上海交通大学图书馆, 2005
[13]申中华,李勇.一种基于MEMS光开关的波长选择开关的设计方法.中国通信学会第五届学术年会论文集. 2008
[14]许端,谢卉,胡强高等.基于液晶技术的1×2 WSS的设计和实验.光通信研究,2008, 6: 40~42
[15]胡强高,孙莉萍,施伟等.具有无干扰切换的波长选择开关.中国,国家发明专利,专利公开号: CN 201194034, 2009. 1~5
[16]胡强高,刘德明,张玓.一种基于微机电系统技术的新型波长选择开关.光学学报, 2010, 30(4): 1168~1172
[17] B.C.Collings. Wavelength Selectable Switches and Future Photonic Network Applications. 2008 International Conference on Photonics in Switching. 2008, 1~4
[18] Pierre Wall, Paul Colbourne, Christopher Reimer, et al. WSS Switching Engine Technologies. Conference on OFC/NFOEC’08, 2008. 1~5
[19]许端.波长选择开关的实现技术分析.中国高校通信类院系学术研讨会论文集(下册), 2009. 445~448
[20]许端,谢卉,胡强高等.基于液晶技术的1×2 WSS的设计和实验.光通信研究, 2008, 150(6): 40~42
[21] Glenn Baxter, Steven Frisken, Dmitri Abakoumov, et al., Highly programmable Wavelength Selective Switch based on Liquid Crystal on Silicon switching elements. Proc OFC/ NFOEC, 2006. 1~3
[22] D.M.Marom, David.T.Neilson, Dennis.S.Greywall, et al. Wavelength-Selective 1×K Switches Using Free Space Optics and MEMS Micromirrors: Theory, Design and Implementation. J.Lightwave Tech., 2005, 23(4): 1620~1630
[23] Jui-che Tsai, Ming C.Wu. Design, Fabrication, and Characterization of a High Fill Factor, Large Scan-Angle,Two-Axis Scanner Array Driven by a Leverage Mechanism. Journal of Microelectromechanical Systems, 2006, 15(5):1209~1213
[24]马志波. MEMS微变形镜测试及工艺防粘附技术研究: [硕士学位论文].西安:西北工业大学图书馆, 2007
[25] Capella光子学公司.减少MEMS微镜边缘衍射的方法.美国,国家发明专利,专利公开号: CN 101384933A, 2009. 1~2
[26]郁道银,谈恒英.工程光学. (第1版).北京:机械工业出版社, 1994. 267~268
[27]陈洪璆,王杰波,曹向群.离子刻蚀矩形位相光栅衍射特性研究.中国光学学会2004年学术大会论文集, 2004. 50~54
[28]刘全,吴建宏.光栅的标量衍射理论与耦合波理论的分析比较.激光杂志, 2004, 25(2): 31~33
[29]樊叔维.二元光栅衍射特性的矢量理论分析.光学精密工程, 1999, 7(5): 30~36
[30]王鹏,徐毓光,余勤跃等.矩形光栅的衍射特性.光子学报, 1999, 28(5): 446~450
[31] M. G. Moharam, Eric B. Grann, and Drew A. Pommet. Formulation for stable and efficient implementation oft he rigorous coupled-wave analysis of binary gratings. J.Opt.Soc.Am. 1995, 12(5): 1068~1076
[32]郑辉.闪耀光栅对厄米—高斯光束的衍射.中国激光, 1982, 10(1): 1~7
[33]赵继德,李应良.全光网络中的MEMS光开关.激光杂志, 2005, 26(3): 10~12
[34]柯昌剑,刘德明.球透镜准直器耦合效率的研究.中国激光, 2002, 6(A29): 371~374
[35]王素芹,阮玉,殷东亮. C-lens准直器回波损耗的理论计算与分析.光电子技术与信息, 2003, 16(1): 24~28
[36]陈海清,曹向英.光盘光学头整形棱镜光学系统的设计.光电工程, 1997, 24(1): 21~25
[37]陈清海.消色差棱镜扩束器.激光与红外, 1987, 7(1): 30~33
[38]刘鈞,高明编.光学设计. (第1版).西安:西安电子科技大学出版社, 2006. 244~ 259
[39] David C.Hanna. Astigmatic Gaussian Beams Produced by Axially Asymmetric Laser Cavities. Journal of Quantum Electronics, 1969, 5(10):483~488
[40]沈学举,郭晓维.三棱镜对圆高斯光束的变换.光学技术, 1999, 1(4): 63~67
[41]赵道木,林强,王绍民.运用张量ABCD定律分析简单象散高斯光束的对称化.杭州大学学报, 1994, 21(1): 36~40
[42] Shifu Yuan, Nabeel A.Riza. General formula for coupling-loss characterization of single-mode fiber collimators by use of gradient-index rod lenses. Applied Optics, 1999, 38(15): 3214~3222
[43]林学煌.光无源器件. (第1版).北京:人民邮电出版社, 1998. 183~187
[44]杨四刚,潘晴,胡必春.基于固体腔F-P标准具的可调谐自适应光滤波器.半导体光电, 2003, 24(2): 107~134
[45] Renzhong Hua, Satoshi Wada, Hideo Tashiro. Principles and limitations of a quarter-wave plate for reducing the depolarization loss from thermally induced birefringence in Nd:YAG lasers. Optics Communications, 2000, 175(1):189~200