有机聚合物电光调制器的设计与实验研究
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摘要
Mach-Zehnder光波导电光调制器是重要的集成光学器件,在民用,国防,科研等领域都起着重要的作用。有机非线性电光聚合物具有电光系数大、易于制备、与半导体工艺兼容、在红外到毫米波波段色散小、响应速度快等优点,已经成为集成光学器件发展的有力推动力量。基于非线性有机聚合物光波导的Mach-Zehnder(M-Z)电光强度调制器目前已经成为各国研究的热点。
本文比较全面地介绍了聚合物电光调制器的发展现状以及未来的发展趋势,然后对基于有机电光聚合物光波导的M-Z强度调制器的制作工艺,理论,测试三个方面做了详细的研究:
对聚合物波导的主要工艺步骤进行了详细的研究。利用真空热蒸发的方法在硅基片上制备了波导下电极;用旋涂的方法制备了聚合物下包层;利用聚合物薄膜电晕极化系统对一种新型生色团DCDHF-2-V和聚甲基丙烯酸甲脂(PMMA)主客掺杂型电光聚合物进行了极化实验;初步研究了针对下包层材料的反应离子刻蚀工艺,并通过对刻蚀样品的台阶仪测试得到了一系列实验参数。这些工作为制作聚合物波导强度调制器的原型器件提供了实验基础。
分别利用两种方法对泰勒级数展开法进行了算法优化和编程实现,并对实际聚合物光波导调制器进行了二维模拟,分析了不同参数下光在M-Z调制器结构中TM基模的模场分布,并得到了以损耗最小为依据的优化结果。还利用二维宽角度Padé方法对对调制器进行了编程实现和模拟,并对比了两种方法的结果。接下来又将Padé方法扩展到三维,不仅得到了波导中横截面TM模基模的模场分布,而且还直观的给出了由于模式形状失配而产生的能量损耗过程。
利用基于简单发射法的聚合物薄膜电光系数测量系统对极化样品进行了测量,但结果明显偏小,随后又对误差产生的原因进行了详细的分析;其次利用棱镜耦合法对波导样品进行了折射率和厚度的测量并利用MATLAB软件实现了求解折射率和厚度的数值方法。
Optical intensity modulator based on Mach-Zehnder waveguide is an important device of Integrated Optics and plays an important role in the field of civilian use, defense,and scientific research.Nonlinear organic E-O polymer has a high E-O coefficient,low fabrication difficulty,compatibility with semiconductor techniques, small dispersion in infrared to millimeter band,fast response and is therefore regarded as an important driving force for the development of integrated optical device. Mach-Zehnder(M-Z) E-O intensity modulator based on nonlinear E-O polymer waveguides is an attractrive research area for many countries.
The current development and the prospect of polymer-waveguide-based devises were introduced at first.Then the theory,fabrication techniques and measurement methods were studied systematically.
The major processing steps of polymer waveguide were studied.The sub-electrode is deposited with the vacuum thermal evaporation technique;the lower cladding layer was obtained by spin-casting;the polling system for polymer thin film was used and experiments are conducted on the sample of the host-guest system of a novel chromophore DCDHF-2-V and PMMA;the Reactive Ion Etch for processing the lower cladding was studied preliminarily and results were obtained with surface profilometry. These works give a solid foundation for the final realization of the prototype of polymer waveguide M-Z modulator.
A numerical method based on the Taylor Series Expansion method was optimized by two methods,realized and will be applied to a real design.The fundamental TM mode distribution in the M-Z modulator with various parameters was analysied,and the optimized result based on the minimum optical power loss was obtained. Two-dimensional simulation employing Padémethod was also realized and the results of the two methods were compared.By expanding the Padémethod to 3-dimension case, the distribution of the fundamental TM mode of the cross section was obtained and a direct view of how the optical power caused by the mode mismatch is lost in the propagation was also obtained.
A system for measuring the E-O coefficient based on the Simple Reflection Method is used to test a polled sample.However,the result was much lower than the reported value,therefore,the possible cause of the difference was analyzed;a waveguide sample is tested with the Prism Coupling Method and the refractive index and thickness is solved numerically using a program designed with Matlab.
本文比较全面地介绍了聚合物电光调制器的发展现状以及未来的发展趋势,然后对基于有机电光聚合物光波导的M-Z强度调制器的制作工艺,理论,测试三个方面做了详细的研究:
对聚合物波导的主要工艺步骤进行了详细的研究。利用真空热蒸发的方法在硅基片上制备了波导下电极;用旋涂的方法制备了聚合物下包层;利用聚合物薄膜电晕极化系统对一种新型生色团DCDHF-2-V和聚甲基丙烯酸甲脂(PMMA)主客掺杂型电光聚合物进行了极化实验;初步研究了针对下包层材料的反应离子刻蚀工艺,并通过对刻蚀样品的台阶仪测试得到了一系列实验参数。这些工作为制作聚合物波导强度调制器的原型器件提供了实验基础。
分别利用两种方法对泰勒级数展开法进行了算法优化和编程实现,并对实际聚合物光波导调制器进行了二维模拟,分析了不同参数下光在M-Z调制器结构中TM基模的模场分布,并得到了以损耗最小为依据的优化结果。还利用二维宽角度Padé方法对对调制器进行了编程实现和模拟,并对比了两种方法的结果。接下来又将Padé方法扩展到三维,不仅得到了波导中横截面TM模基模的模场分布,而且还直观的给出了由于模式形状失配而产生的能量损耗过程。
利用基于简单发射法的聚合物薄膜电光系数测量系统对极化样品进行了测量,但结果明显偏小,随后又对误差产生的原因进行了详细的分析;其次利用棱镜耦合法对波导样品进行了折射率和厚度的测量并利用MATLAB软件实现了求解折射率和厚度的数值方法。
Optical intensity modulator based on Mach-Zehnder waveguide is an important device of Integrated Optics and plays an important role in the field of civilian use, defense,and scientific research.Nonlinear organic E-O polymer has a high E-O coefficient,low fabrication difficulty,compatibility with semiconductor techniques, small dispersion in infrared to millimeter band,fast response and is therefore regarded as an important driving force for the development of integrated optical device. Mach-Zehnder(M-Z) E-O intensity modulator based on nonlinear E-O polymer waveguides is an attractrive research area for many countries.
The current development and the prospect of polymer-waveguide-based devises were introduced at first.Then the theory,fabrication techniques and measurement methods were studied systematically.
The major processing steps of polymer waveguide were studied.The sub-electrode is deposited with the vacuum thermal evaporation technique;the lower cladding layer was obtained by spin-casting;the polling system for polymer thin film was used and experiments are conducted on the sample of the host-guest system of a novel chromophore DCDHF-2-V and PMMA;the Reactive Ion Etch for processing the lower cladding was studied preliminarily and results were obtained with surface profilometry. These works give a solid foundation for the final realization of the prototype of polymer waveguide M-Z modulator.
A numerical method based on the Taylor Series Expansion method was optimized by two methods,realized and will be applied to a real design.The fundamental TM mode distribution in the M-Z modulator with various parameters was analysied,and the optimized result based on the minimum optical power loss was obtained. Two-dimensional simulation employing Padémethod was also realized and the results of the two methods were compared.By expanding the Padémethod to 3-dimension case, the distribution of the fundamental TM mode of the cross section was obtained and a direct view of how the optical power caused by the mode mismatch is lost in the propagation was also obtained.
A system for measuring the E-O coefficient based on the Simple Reflection Method is used to test a polled sample.However,the result was much lower than the reported value,therefore,the possible cause of the difference was analyzed;a waveguide sample is tested with the Prism Coupling Method and the refractive index and thickness is solved numerically using a program designed with Matlab.
引文
[1]唐天同,王兆宏,陈时.集成光电子学.西安:科学出版社,2005,20-21
[2]西原浩,春名正光,栖原敏明.集成光路.北京:科学出版社,2004,4-5
[3]Miller S E.Integrated Optics:An Introduction.Bell System Technical Journal,1969,48:2059-2061
[4]于荣金.集成光学和光子学.光电子激光,1998,9(2):162-165
[5]Dalton L R,Harper A W,et al.Adv Master.,1995,7(6):519
[6]SHI Y Q,WANG W S,BECH J H,et al.Fabrication and characterization of high-speed poly-urethane-disperse red 19 integrated electro-optic modulators for analog system applications.IEEE J Slected Topics in Quan Electron,1996,2(2):289-299.
[7]Sang-Shin Lee,Sean M,Garner,et al.Optical Intensity Modulator Based on a Novel Electrooptic Polymer Incorporating a High μβ Chromophore.IEEE Jounal of Quantum Electronics,2000,36(5):527-532
[8]吕新杰,杨军,明海.聚合物光波导器件的最新进展.光电子技术与信息,2004,17(6):6-11
[9]Eldada L,Yin S,Poga C,et al.IEEE Photon Technol Lett,1998,10:1416
[10]Smith BA,Junch M,Moerner W E,et al.Proc SPIE,1996,2852:258
[11]Chen D,Fetterman H R,Chen A,et al.Proc SPIE,1997,3006:314
[12]http://spie.org/x16998.xml
[13]Y.Huang,G.T.Paloczi,A.Yariv,C.Zhang,et al.Fabrication and replication of polymer integrated optical devices using electron-beam lithography and softlithography.Phys.Chem.,2004,B(108):8606-8613.
[12]Professor Larry R.Dalton,Chemistry Department,University of Washington,Box 351700,Seattle,WA,98195(personal communication 2006)
[13]W.warzanskij,F.Heismann and R.C.Alferness.Polarization-independent electro-optically tunable narrow-band wavelength filter.Appl Phys Lett,1988,53:13
[14]Siong-ku Kim,H.Zhang,D.H.Chang,et al.Electrooptic polymer modulators with an inverted-rib waveguide structure.Photonics Technology Letters,2003,15(2):218-220
[15]A.S.Liu,R.Jones,L.Liao,etc al.A high-speed silicon optical modulator based on a metal-oxide-semiconductor capacitor.Nature,2004,427:615-618
[16]O.Mitomi,K.Noguchi and H.Miyazawa.Broadband and low driving-voltage LiNbO3 optical modulators.IEEE Proc.Optoelectron.,1998,135:360-364
[17]Y.Q.Shi,C.Zhang,H.Zhang,J.H.Bechtel,et al.Low(sub-1-volt) halfwave voltage polymeric electro-optic modulators achieved by controlling chromophore shape.Science,2000,288:119-122
[18]Y.Enami,C.T.Derose,D.Mathine,et al.Hybrid polymer/sol-gel waveguide modulators with exceptionally large electro-optic coefficients.Nature Photon,2007 6:180-185
[19]M.Hochberg,T.Baehr-Jones,G.Wang,et al.Towards a millivolt optical modulator with nano-slot waveguides.Optics Express,2007,15(3):8401-8410
[20]Tom Baehr-Jones,Michael Hochberg,Chris Walker,etc al.Analysis of tuning sensitivity of SOI optical ring resonatior.Journal of Lightwave Technology,2005,23(12):4215-4221
[21]L.R.Dalton.Novel polymer-based high speed electrooptic devices,in Proceedings of the 23rd European Conference on Optical Communications/14th International Conference on Integrated Optics and Optical Fibre Communication,2003,vol.2:246-249
[22]Larry Dalton,A Harper,A Ren,etc al.Polymeric electro-optic modulators:from chromophore design to Integration with Semiconductor Very Large Scale Integration Electronics and Silica Fiber Optics.Chem.Res.,1999,38:8-33
[23]Anurag Sharma,Arti Agrawal.A new finite-differene-based method for wide-angle beam propagation.Photonics Technology,2006,18(8):944-946
[24]Srinivasan R,Braren B.Ultraviolet laser ablation and etching of polymethyl methacrylate sensitized with an organic dopant.Appl.Phys.A,1988,45(289):111-114
[25]徐建东,鲍信先,李淳飞.非线性光学聚合物的极化技术.高技术通讯,1997,10,59-61
[26]Michal Quik,Julian Serda.半导体制造技术.北京:电子工业出版社,2003,310-336
[27]田民波.薄膜技术与薄膜材料.北京:清华大学出版社,2006,610-619
[28]廖进昆,刘永智,廖翊韬,等.聚合物电光调制器中M—Z波导TM模分析.应用光学,2006,27(2):129-132
[29]A Splett,M Majd,K Petermann.A Novel Beam Propagation Method for Large Refractive Index Steps and Large Propagation Distances.IEEE Photonics Technology Letters,1991,3(5):466-468
[30]Kenji Kawano.T.K,Introduction to optical waveguide analysis:Solving maxwells equations and Schrodinger equation.New York:John Wily & Sons,Inc.,Publisher,2001,70-72
[31]Anurag Sharma,Arti Agrawal.A new finite-differene-based method for wide-angle beam propagation.Photonics Technology,2006,18(8):944-946
[32]G.Ronald Hadley.Transparent boundary condition for the beam propagation method.IEEE Quantum Electronics,1992,28(1):551-554
[33]G.Ronald Hadley.Wide angle beam propagation using pade approximant operatiors.Optics Letters,1992,17(20):224-228
[34]G.Ronald Hadley.Multistep method for wide-angle beam propagation.Integrated Photon.Res.,1993,Itu(I5-1):387-391
[35]S.H.Han,J.W.Wu.Single-beam polarization intefferomentry measurement of the linear electro-optical effect in poled polymer films with a reflection configuration.1997,14(5):1131-1137
[36]C.C.Teng,H.T.Man,Simple reflection technique for measuring the electro-optical coefficient of poled polymers,Appl Phys.Lett,1990,56(18):1734-1736
[37]史伟,房昌水,潘奇伟,等.简单反射法测量聚合物薄膜线性电光系数的研究.物理学报2000,49(2):262-266
[38]蔡伯荣,谭志飞,孙守瑶,等.集成光学.成都:电子科技大学出版社,1990,252-254
[39]I.P.Kaminow,L.W.Stulz.Loss in deaved Ti-diffused LiNbO3 wavegides.Appl.Phys.Lett.,1978,33(1):62
[40]H.P.Weber,F.A.Dunn,W.N.Leibolt.Loss measurements in thin film optical waveguides.Appl.Opt.,1973,12(4):3445
[41]J.E.Goell,R.D.Standley.Sputtered glass waveguide for integrated optical circuits.Bell Syst.Tech,1969,48(10):3445
[42]Cha-Chi Teng.Precision measurements of the optical attenuation profile along the propagation path in thin-film waveguides.Applied Optics,1993,32(7):1051-1054
[2]西原浩,春名正光,栖原敏明.集成光路.北京:科学出版社,2004,4-5
[3]Miller S E.Integrated Optics:An Introduction.Bell System Technical Journal,1969,48:2059-2061
[4]于荣金.集成光学和光子学.光电子激光,1998,9(2):162-165
[5]Dalton L R,Harper A W,et al.Adv Master.,1995,7(6):519
[6]SHI Y Q,WANG W S,BECH J H,et al.Fabrication and characterization of high-speed poly-urethane-disperse red 19 integrated electro-optic modulators for analog system applications.IEEE J Slected Topics in Quan Electron,1996,2(2):289-299.
[7]Sang-Shin Lee,Sean M,Garner,et al.Optical Intensity Modulator Based on a Novel Electrooptic Polymer Incorporating a High μβ Chromophore.IEEE Jounal of Quantum Electronics,2000,36(5):527-532
[8]吕新杰,杨军,明海.聚合物光波导器件的最新进展.光电子技术与信息,2004,17(6):6-11
[9]Eldada L,Yin S,Poga C,et al.IEEE Photon Technol Lett,1998,10:1416
[10]Smith BA,Junch M,Moerner W E,et al.Proc SPIE,1996,2852:258
[11]Chen D,Fetterman H R,Chen A,et al.Proc SPIE,1997,3006:314
[12]http://spie.org/x16998.xml
[13]Y.Huang,G.T.Paloczi,A.Yariv,C.Zhang,et al.Fabrication and replication of polymer integrated optical devices using electron-beam lithography and softlithography.Phys.Chem.,2004,B(108):8606-8613.
[12]Professor Larry R.Dalton,Chemistry Department,University of Washington,Box 351700,Seattle,WA,98195(personal communication 2006)
[13]W.warzanskij,F.Heismann and R.C.Alferness.Polarization-independent electro-optically tunable narrow-band wavelength filter.Appl Phys Lett,1988,53:13
[14]Siong-ku Kim,H.Zhang,D.H.Chang,et al.Electrooptic polymer modulators with an inverted-rib waveguide structure.Photonics Technology Letters,2003,15(2):218-220
[15]A.S.Liu,R.Jones,L.Liao,etc al.A high-speed silicon optical modulator based on a metal-oxide-semiconductor capacitor.Nature,2004,427:615-618
[16]O.Mitomi,K.Noguchi and H.Miyazawa.Broadband and low driving-voltage LiNbO3 optical modulators.IEEE Proc.Optoelectron.,1998,135:360-364
[17]Y.Q.Shi,C.Zhang,H.Zhang,J.H.Bechtel,et al.Low(sub-1-volt) halfwave voltage polymeric electro-optic modulators achieved by controlling chromophore shape.Science,2000,288:119-122
[18]Y.Enami,C.T.Derose,D.Mathine,et al.Hybrid polymer/sol-gel waveguide modulators with exceptionally large electro-optic coefficients.Nature Photon,2007 6:180-185
[19]M.Hochberg,T.Baehr-Jones,G.Wang,et al.Towards a millivolt optical modulator with nano-slot waveguides.Optics Express,2007,15(3):8401-8410
[20]Tom Baehr-Jones,Michael Hochberg,Chris Walker,etc al.Analysis of tuning sensitivity of SOI optical ring resonatior.Journal of Lightwave Technology,2005,23(12):4215-4221
[21]L.R.Dalton.Novel polymer-based high speed electrooptic devices,in Proceedings of the 23rd European Conference on Optical Communications/14th International Conference on Integrated Optics and Optical Fibre Communication,2003,vol.2:246-249
[22]Larry Dalton,A Harper,A Ren,etc al.Polymeric electro-optic modulators:from chromophore design to Integration with Semiconductor Very Large Scale Integration Electronics and Silica Fiber Optics.Chem.Res.,1999,38:8-33
[23]Anurag Sharma,Arti Agrawal.A new finite-differene-based method for wide-angle beam propagation.Photonics Technology,2006,18(8):944-946
[24]Srinivasan R,Braren B.Ultraviolet laser ablation and etching of polymethyl methacrylate sensitized with an organic dopant.Appl.Phys.A,1988,45(289):111-114
[25]徐建东,鲍信先,李淳飞.非线性光学聚合物的极化技术.高技术通讯,1997,10,59-61
[26]Michal Quik,Julian Serda.半导体制造技术.北京:电子工业出版社,2003,310-336
[27]田民波.薄膜技术与薄膜材料.北京:清华大学出版社,2006,610-619
[28]廖进昆,刘永智,廖翊韬,等.聚合物电光调制器中M—Z波导TM模分析.应用光学,2006,27(2):129-132
[29]A Splett,M Majd,K Petermann.A Novel Beam Propagation Method for Large Refractive Index Steps and Large Propagation Distances.IEEE Photonics Technology Letters,1991,3(5):466-468
[30]Kenji Kawano.T.K,Introduction to optical waveguide analysis:Solving maxwells equations and Schrodinger equation.New York:John Wily & Sons,Inc.,Publisher,2001,70-72
[31]Anurag Sharma,Arti Agrawal.A new finite-differene-based method for wide-angle beam propagation.Photonics Technology,2006,18(8):944-946
[32]G.Ronald Hadley.Transparent boundary condition for the beam propagation method.IEEE Quantum Electronics,1992,28(1):551-554
[33]G.Ronald Hadley.Wide angle beam propagation using pade approximant operatiors.Optics Letters,1992,17(20):224-228
[34]G.Ronald Hadley.Multistep method for wide-angle beam propagation.Integrated Photon.Res.,1993,Itu(I5-1):387-391
[35]S.H.Han,J.W.Wu.Single-beam polarization intefferomentry measurement of the linear electro-optical effect in poled polymer films with a reflection configuration.1997,14(5):1131-1137
[36]C.C.Teng,H.T.Man,Simple reflection technique for measuring the electro-optical coefficient of poled polymers,Appl Phys.Lett,1990,56(18):1734-1736
[37]史伟,房昌水,潘奇伟,等.简单反射法测量聚合物薄膜线性电光系数的研究.物理学报2000,49(2):262-266
[38]蔡伯荣,谭志飞,孙守瑶,等.集成光学.成都:电子科技大学出版社,1990,252-254
[39]I.P.Kaminow,L.W.Stulz.Loss in deaved Ti-diffused LiNbO3 wavegides.Appl.Phys.Lett.,1978,33(1):62
[40]H.P.Weber,F.A.Dunn,W.N.Leibolt.Loss measurements in thin film optical waveguides.Appl.Opt.,1973,12(4):3445
[41]J.E.Goell,R.D.Standley.Sputtered glass waveguide for integrated optical circuits.Bell Syst.Tech,1969,48(10):3445
[42]Cha-Chi Teng.Precision measurements of the optical attenuation profile along the propagation path in thin-film waveguides.Applied Optics,1993,32(7):1051-1054