乙基红掺杂有机薄膜的制备及全光开关性能研究

用溶胶-凝胶法及重复旋转涂膜法制备了乙基红偶氮染料与聚甲基丙烯酸甲酯(PMMA)掺杂聚合物薄膜样品,测量薄膜样品的全光开关特性的结果表明,选择合适的掺杂浓度(2wt%～6wt%)和偶极矩较大的极性溶剂(环已酮)制备的薄膜样品,在室温条件下对8mW的控制光功率及周期为0.66ms的控制光乙基红有机聚合物薄膜来说,具有毫秒量级的开关响应速度和40%以上的开关调制深度,最大的调制深度达72%.     

核壳结构偶氮聚合物的全光开关效应研究

分别用主客掺杂法和种子乳液聚合法制备了含相同浓度偶氮染料分散红4-(2-hydroxyethyl) ethylamino-2-chloro-4-nitroazobenzene(Disperse Red 13,DR13)的聚甲基丙烯酸甲酯poly(methyl methacrylate)(PMMA)均匀薄膜样品.用经斩波器调制的线偏振氩离子激光(514 nm,CW)作用于样品产生光致双折射.作为探测光的线偏振氦氖激光(633nm,CW)经过样品,通过与原来偏振方向垂直的检偏器的透射光强强度的调制,实现了光控光的全光开关效应.研究比较了两种样品在控制不同光功率下的光致双折射效应和全光开关效应,比较发现用种子乳液聚合法制备的具有核壳结构的样品在控制光功率、开关时间及开关调制深度等方面均优于主客掺杂样品.     

线-圆双偏振态光束抽运有机聚合物全光开关

为了有效降低偶氮苯聚合物薄膜全光开关信号的本底,提高全光开关信号的调制深度,利用线偏振光合成圆偏振光的原理,设计了一种新的线-圆双偏振态光束抽运光路。实验用532 nm光作为抽运光,632.8 nm的He-Ne激光作为探测光。532 nm的光先分为功率相等但偏振正交、相位差为π/2奇数倍的两束线偏振光,然后再合成一束抽运光。通过调制其中的一束来实现线偏振与圆偏振抽运光之间的转换,从而实现样品光致双折射的产生与擦除。以掺杂分散红1(DR1)的聚甲基丙烯酸甲酯薄膜(PMMA)为样品进行实验。结果表明,用此光路,样品全光开关信号的调制深度达到92%,远远高于传统的单一线偏振光束抽运光路的实验结果。     

毫秒有机聚合物薄膜全光开关

用聚甲基丙烯酸甲酯(PMMA)和偶氮染料DRl以一定的比例混合，制成各向同性均匀薄膜样品。用经斩波器调制的线偏振氩离子激光(514nm，CW)作用样品产生光致双折射。作为探测光的线偏振氦氖激光(633nm，CW)经过样品，在与其原来偏振方向垂直的检偏器后的透射光强强度受控制光的调制作用，实现了光控光的全光开关效应。通过改变控制光的光功率及薄膜样品的温度。对样品的开关响应速度和开关调制深度进行了研究。在一定的实验条件下，用毫瓦量级的控制光功率实现了几个毫秒的开关响应速度和60％以上的开关调制深度。     

主客体掺杂的偶氮类聚合物

摘　要: 采用旋转甩膜法制备了主客体掺杂型的偶氮类聚合物薄膜, 构成薄膜的光学活性生色团包括分散红1、分散橙 25、分散黄7、分散红54, 基体为聚甲基丙烯酸甲酯( PM MA) 或聚碳酸酯( PC) 。利用扫描电镜( SEM) 、X 射线衍射 ( XRD) 、差示扫描量热计( DSC) 、红外光谱法( IR) 、紫外-可见吸收谱仪和显微硬度仪等对样品的表面、染料的结晶性、玻 璃化转变温度、掺杂聚合物的结构、薄膜的吸收谱以及硬度进行了分析。并系统研究了工艺条件对偶氮类聚合物薄膜的 全光极化特性的影响。实验表明, 分散染料浓度越大光极化产生的二阶非线性效应越强, 这与单位面积内聚合物薄膜中含有较高浓度的分散红有关。通过普通热处理的聚合物薄膜样品, 在避光保存的条件下, 产生的全光极化效果最明显。总 之, 偶氮类聚合物薄膜全光极化下的二次谐波强度与其制备过程中的参数有密切的关系。     

主客体掺杂的偶氮类聚合物薄膜的制备和全光极化特性

采用旋转甩膜法制备了主客体掺杂型的偶氮类聚合物薄膜．构成薄膜的光学活性生色团包括分散红1、分散橙25、分散黄7、分散红54,基体为聚甲基丙烯酸甲酯(PMMA)或聚碳酸酯(PC)。利用扫描电镜(SEM)、X射线衍射(XRD)、差示扫描量热计(DSC)、红外光谱法(IR)、紫外-可见吸收谱仪和显微硬度仪等对样品的表面、染料的结晶性、玻璃化转变温度、掺杂聚合物的结构、薄膜的吸收谱以及硬度进行了分析。并系统研究了工艺条件对偶氮类聚合物薄膜的全光极化特性的影响。实验表明,分散染料浓度越大光极化产生的二阶非线性效应越强,这与单位面积内聚合物薄膜中含有较高浓度的分散红有关。通过普通热处理的聚合物薄膜样品,在避光保存的条件下,产生的全光极化效果最明显。总之,偶氮类聚合物薄膜全光极化下的二次谐波强度与其制备过程中的参数有密切的关系。     

二芳基乙烯薄膜双稳态全光开关的实验研究

采用二芳基乙烯(DA,diarylethene)材料顺-1,2-二氰基-1,2-双(2,4,5-三甲基-3-噻吩基) 乙烯cis-1,2-Dicyano-1,2-bis(2,4,5-trimethyl-3-thie nyl)ethene掺杂到聚甲基丙烯酸甲酯 (PMMA)制成有机掺杂薄膜样品(掺杂质量百分比为10%),基于薄膜 光致吸收特性的变化 构建了有机掺杂薄膜双稳态全光开关,分别以波长为375nm的紫外激 光(CW,40mW)和 波长为532nm的可见激光(CW,5mW)作为激发光,以波长为632.8nm的He-Ne激光(CW,3μW)为探 测光,实验研究并获得了薄膜样品的双稳态全光开关实验结果,开关信号的调制深 度为8.2%,开关上升时间约为36s,下降时间 约为47s。根据光致变色系统二能级 理论,对全光开关的实验结果和机理作了较深入分析。本文的双稳态全光开关具有简单 容易实现的特点,作为一种低速的双稳态全光开关有潜在应用价值。     

氧化钒薄膜的制备及其在光激励下对太赫兹波的调制

采用磁控溅射法在蓝宝石基底上制备金属钒薄膜,然后在O2中快速热处理获得具有相变特性的VOx薄膜。实验对比了不同的热处理温度和热处理时间对薄膜性能的影响,薄膜的结晶状况用X射线衍射(XRD)进行分析;利用THz时域频谱系统,观测薄膜在不同激励光功率下的相变特性及其对THz波的调制作用。结果表明,在570℃条件下快速热处理60s所制得的VOx薄膜性能最佳,薄膜对THz波透过性最好,光激励后对THz波的调制作用最大,调制幅度达到83.9%,且引发相变的功率阈值低。     

太赫兹时间分辨系统研究有机卤化物钙钛矿薄膜的超快太赫兹调制

研究了利用太赫兹时间分辨系统研究有机卤化物钙钛矿薄膜(CH_3NH_3PbI_3 and CH_3NH_3PbI_(3-x)Cl_x)的皮秒尺度的超快太赫兹调制特性.在光激发作用下出现了太赫兹透射波的瞬时下降.相比于CH_3NH_3PbI_3薄膜,在光激发作用下CH_3NH_3PbI_(3-x)Cl_x薄膜展现了更高的调制深度(10%).通过测算材料的电导率及载流子浓度,其调制机理为瞬态光激发载流子浓度上升.实验结果表明,CH_3NH_3PbI_(3-x)Cl_x薄膜可作为一种高效超快太赫兹调制器件.     

太赫兹时间分辨系统研究有机卤化物钙钛矿薄膜的超快太赫兹调制（英文）

研究了利用太赫兹时间分辨系统研究有机卤化物钙钛矿薄膜(CH_3NH_3PbI_3 and CH_3NH_3PbI_(3-x)Cl_x)的皮秒尺度的超快太赫兹调制特性.在光激发作用下出现了太赫兹透射波的瞬时下降.相比于CH_3NH_3PbI_3薄膜,在光激发作用下CH_3NH_3PbI_(3-x)Cl_x薄膜展现了更高的调制深度(10%).通过测算材料的电导率及载流子浓度,其调制机理为瞬态光激发载流子浓度上升.实验结果表明,CH_3NH_3PbI_(3-x)Cl_x薄膜可作为一种高效超快太赫兹调制器件.     

Electron-beam controlled switching using quartz and polycrystallineZnS

Results of electron-beam controlled switching experiments with switch samples of quartz crystal and polycrystalline zinc selenide (ZnSe) are presented. For switch samples of both materials, drastic reductions of the switch resistance were induced by the electron beam. The quartz sample showed very fast temporal response (less than 1 ns) with potential applicability for current control. The ZnSe samples, on the other hand, showed longer current transients (on the order of 10 ns) with exponential development of the switch resistance after the electron beam pulse     

分子束外延In掺杂硅基碲镉汞研究

利用分子束外延(Molecular Beam Epitaxy, MBE)系统生长了In掺杂硅基碲镉汞(Mercury Cadmium Telluride, MCT)材料。通过控制In源温度获得了不同掺杂水平的高质量MCT外延片。二次离子质谱仪(Secondary Ion Mass Spectrometer, SIMS)测试结果表明,In掺杂浓度在1×10¹⁵～2×10¹⁶ cm^-3之间。表征了不同In掺杂浓度对MCT外延层位错的影响。发现位错腐蚀坑形态以三角形为主(沿<■>方向排列),且位错密度与未掺杂样品基本相当。对不同In掺杂浓度的材料进行汞饱和低温处理后,样品的电学性能均有所改善。结果表明,In掺杂能够提高材料的均匀性,从而获得较高的电子迁移率。     

Photoluminescence Characterization of Boron-doped Si Layers Grown by Molecular Beam Epitaxy

Photoluminescence spectra were used to characterize the boron-doped Si layers grown by molecular beam epitaxy using HBO2 as the doping source. The influence of boron doping concentration on the dislocation-related photoluminescence spectra of molecular beam epitaxy Si layers annealed at 900 ℃ was studied with different doping concentrations and growth temperature. The broad photoluminescence band（from 0.75 eV to 0. 90 eV） including D1 and D2 bands was associated with high boron doping concentration in the samples, while D3 and D4 bands might be related to oxygen precipitates.     

Design of multimode interference optical switches with area modulation

Based on the self-imaging effect, multimode interference (MMI) optical switches with area modulation were proposed. The field transfer matrix was introduced to analyze the MMI switches. As an example, the phase modulation parameters of a 3 × 3 MMI switch for different switching cases were obtained by solving the field transfer equation. And the finite-difference beam propagation method (FD-BPM) was used to confirm the analytical results.     

Laser beam modulation using corner reflector and deep diffraction grating

A new scheme of the power modulator of laser beam is based on a corner-reflector unit with a relief diffraction grating that is placed on a plane of the unit and has a relief depth of several wavelengths of the laser radiation. It is shown that angular oscillations of the unit make it possible to implement modulation of the zero-order diffraction beam at a modulation depth of almost 100% and a relatively high linearity of the modulation characteristic that is reached at modulation depths of greater than 50%.     

Accurate measurement of composition, carrier concentration, and photoconductive lifetime in Hg1−xCdxTe grown by molecular beam epitaxy

Variable magnetic field Hall and transient photoconductance lifetime measurements were performed on a series of undoped, In-doped, and As-doped HgCdTe samples grown by molecular beam epitaxy and metalorganic chemical vapor deposition. Temperature variation and, in the case of Hall, magnetic-field variation are needed to give a more complete picture of the mechanisms that control lifetimes in HgCdTe samples. Recent predictions of recombination lifetimes from full band structure calculations were compared to experimental lifetimes at various doping levels at long-wave infrared (LWIR) and mid-wave infrared (MWIR) compositions. For n-type material, lifetimes from low doping levels fall well below the predictions, implying that Shockley-Read-Hall (SRH) recombination is still dominant. MWIR samples have a lifetime that increases somewhat with carrier concentration, suggesting that In doping passivates the SRH defects for that composition. Lifetimes in p-type MWIR material appear to be well-explained by recent theoretical calculations. In p-type material, trapping states may be introduced during the incorporation and activation of As, since some samples with unusually long lifetimes had a distinctly different type of temperature dependence.     

2×2 InP/InGaAsP MMI-MZI型光开关设计与实验

主要研究基于多模干涉耦合器(MMI)的2×2 InP/InGaAsP马赫曾德型(MMI-MZI)光开关.开关的特性采用BPM(光束传输法)进行器件建模、参数分析与性能优化.开关的结构按照传输波导保证单模传输、低偏振敏感要求进行了设计.光开关通过载流子电注入产生的载流子吸收和带填充效应改变移相臂传输光相位.实验测得光开关在控制电压为6.4 V时可实现交叉态到直通态的倒换,开关和关态串扰分别为-20.49 dB、-19.19 dB.这种开关具有结构紧凑、制作容差大和偏振无敏感等优点,它可以很方便地和其它半导体有源器件集成,在未来DWDM系统中有着非常广泛的应用前景.