【作者】 孙强；

【导师】 任诠； 王新强；

【作者基本信息】 山东大学 ， 光学工程， 2010， 硕士

【摘要】 随着三网融合和3G时代的到来,人们对带宽的需求越来越高,高速宽带综合业务网络已成为本世纪通信网络的发展趋势。由于全光网络中的信号传输全部在光域内进行,因此,全光网络具有对信号的透明性,它通过波长选择器件实现路由选择。全光网络以其良好的透明性、波长路由特性、兼容性和可扩展性,成为下一代高速(超高速)宽带网络的首选。全光开关作为全光网络的关键器件,可实现在全光层的路由选择、波长选择、光交叉连接以及自愈保护等重要功能。当前,国际上还没有找到适合做全光开光的材料,对全光开关材料的研究日益成为全光通信领域关注的焦点。全光开关是利用材料的三阶非线性光学效应,即光学克尔效应。用一束控制光引起材料的非线性折射率变化,使信号光通过该器件时产生相位变化,从而实现光开关的开关动作。全光开关器件要求材料具有高非线性折射率、低的线性和非线性吸收和快的响应速度。三阶非线性光学材料性能参数的准确表征是研究材料性能的重要手段,可以对材料的探索、改进和器件的设计提供参考和依据。本论文的主要内容如下：第一,根据全光网络中全光开关器件材料品质因子W(W=n2I/α0λ)和T(T=βλ/n2)的要求,结合1,3-二硫杂环戊烯-2-硫酮-4,5-二硫基(DMIT)类材料具有优良的平面π电子共轭结构特点,设计和合成了两种DMIT类材料—多硫酮衍生物材料4,5-二苯甲酰硫基-1,3-二硫杂环戊烯-2-硫酮(BBDT)和金属有机配合物材料1,3-二硫杂环戊烯-2-硫酮-4,5-二硫基合金十六烷基三甲基铵盐(CtAu)。其中,CtAu材料的三阶非线性光学性质被首次报道。为了给以后器件设计提供理论和实验依据,将上述两种材料与光学透明性好,玻璃化温度高,容易成膜的聚甲基丙烯酸甲酯(PMMA)采用旋涂法制备成聚合物复合薄膜。第二,用准波导方法对聚合物复合薄膜BBDT/PMMA和CtAu/PMMA的线性折射率和厚度进行了表征。准波导方法是基于平面波的光波簇干涉理论和米氏散射理论发展而来,测量中只要求角度测量,方便且精度高。运用Z扫描技术对BBDT和CtAu材料的溶液与聚合物复合薄膜在1064和532nm波长下的非线性折射和非线性吸收性质进行了表征和研究。Z扫描技术是基于基模高斯光束的空间光束畸变的原理,利用光束横向效应来测量材料光学非线性性质。利用获得的两种材料在1064和532nm波长下的闭孔和开孔归一化Z扫描透过率曲线,通过数据拟合可以计算出材料的非线性折射率,非线性吸收系数和三阶非线性极化率。结果表明,BBDT材料的溶液和薄膜均表现出白聚焦性质,即非线性折射率n2为负值；CtAu材料的溶液和薄膜均表现出自散焦性质,即非线性折射率n2为正值。第三,通过运用Z扫描技术对BBDT和CtAu材料的溶液与聚合物复合薄膜在1064和532nm波长下的非线性折射和非线性吸收性质的表征和研究,得到一系列研究结论：激光脉冲宽度(1064nm时,脉冲宽度为20ps；532nm时,脉冲宽度为14ps)小,重复频率(10Hz)低,因此热效应可以忽略,两种材料的非线性折射率来源于DMIT材料大π电子共轭结构；CtAu材料由于金属原子的引入,产生了金属到配位体和配位体到会属的电荷转移态,导致其非线性光学系数比BBDT大；在共振波长532nm处由于存在非线性吸收,因此,此处的三阶非线性极化率比非共振波长1064nm处的大；材料聚合物复合薄膜的非线性光学系数由于其表面局域场增强效应比溶液的大；随着薄膜掺杂浓度的增大,其非线性光学系数也随之增大。通过对浓度1.0×10-3mol／L的CtAu／乙腈溶液的响应时间的测量发现,它的响应时间为195fs。短的响应时间和大的非线性极化率表明该类材料是很有前途的光子学材料。本研究工作得到了国家自然科学基金(批准号：60778037)和高等学校全国优秀博士学位论文专项资金课题(批准号：200539)的支持。更多还原

【Abstract】 With the appearance of the 3G era and the integration of telecommunications networks, cable television networks and the internet, the demand for bandwidth is greater and greater, so the high-speed broadband integrated service network has become the development trend of the modern communications network. As the signal transmits in all-optical network is in optical domain, therefore, all-optical network has the advantage of the transparency of the signal and achieves the routing selection through wavelength routing device. All-optical network becomes the first choice of the next-generation high speed (ultra-high speed) broadband network for its good transparency, wavelength routing feature, compatibility and scalability.As the key device of all-optical networks, all-optical switching can realize the functions of routing selection, wavelength selection, optical cross-connect and self-healing protection in all-optical layer. At present, the nonlinear optical material which is suitable for all-optical switching hasn’t been found yet, hence its investigation has increasingly become the focus of the all-optical communication field.The principle of all-optical switching is taking advantage of the third-order nonlinear optical effect of materials, namely optical Kerr effect. With a control beam inducing the change of refractive index of materials, the other signal beam transmitting in the material will produce an additional phase difference, therefore to realize the function "on" and "off"of optical switching. All-optical switching devices require materials with high third-order nonlinear refractive index, lower linear and nonlinear absorption and faster response time.Therefore, the precise characterization of third-order nonlinear optical properties is significant to explore materials, optimize materials to satisfy the requirement of optical devices.My main work is as follows:Firstly, according to merit factors W(w=n2I/a0λ)and T(T=βλ/n2)of material which is suitable for all-optical switching, we designed and synthesized two materials with conjugation of theπelectron, one is multi-thione derivatives material 4,5-bis(benzoylthio)-1,3-dithiole-2-thione (BBDT) and the other is metal-organic material hexadecyltrimethylammonium bis(1,3-dithiole-2-thione-4,5-dithiolato) aurate(III), (CtAu).The third-order nonlinear optical properties of the CtAu material were first reported.In order to provide theoretical and experimental evidence for the device design, We mixed BBDT and CtAu with polymethyl methacrylate (PMMA) which has the advantage of high glass transition temperature, excellent optical transparency, ease of film forming polymer. We prepared CtAu/PMMA, BBDT/PMMA composite film by spin-coating method.Secondly, the linear refractive indexes and thicknesses of polymer composite film BBDT/PMMA and CtAu/PMMA were characterized by quasi-waveguide method. Quasi-waveguide method is developed from plane light wave interference theory and the Mie scattering cluster theory. The method is convenient and with high accuracy which only needs angle measurement. The nonlinear refraction and absorption properties of BBDT and CtAu solution and polymer composite film at the wavelength of 1064 and 532nm were characterized and studied using Z scan technique. Z scan technique is based on the principle of special fundamental mode Gaussian beam distortion, which measures the nonlinear optical properties of materials using the horizontal effect of fundamental mode Gaussian beam. The nonlinear refractive index, nonlinear absorption and third-order nonlinear susceptibility of the two materials can be calculated by fitting the data we got from closed aperture and open aperture Z scan experiment. The results show that BBDT solution and BBDT/PMMA exhibit self-focusing property and CtAu solution and CtAu/PMMA exhibit self-defocusing property.Thirdly, by characterizing and studying the nonlinear refraction and nonlinear absorption of BBDT and CtAu solution and polymer composite film at the wavelength of 1064 and 532nm using Z scan technique, a series of conclusions are as follows:Laser pulse width (20ps when wavelength is 1064nm,14ps when wavelength is 532nm) is small and repetition rate(lOHz) is low, so thermal effects can be neglected. The nonlinear refractive indexes of two materials are from the structure of largeπ-electron conjugation.The third-order nonlinear susceptibility of CtAu material is larger than BBDT because of the introduction of the metal atom, which results in the charge transfer state of metal to the ligand and ligand to metal.The third-order nonlinear susceptibility at the wavelength of 532nm is larger than that at the wavelength of 1064nm because of the nonlinear absorption at the wavelength of 532nm. The nonlinear optical coefficient of the film is larger than that of the solution because of the surface local field enhancement.The nonlinear optical coefficient increases as thin film doping concentration increases. The response time of CtAu/acetonitrile solution with the concentration of 1.O×10-3mol/L is measured to be 195fs.Short response time and large nonlinear susceptibility showed that these materials are promising photonic materials.The study is supported by the National Natural Science Foundation of China (Grant No.60778037) and the Foundation for the Author of National Excellent Doctoral Dissertation of P. R. China (Grant No.200539).更多还原