M-Z型极化DANS聚合物电光波导强度调制器研究

研究了Mach-Zehnder型极化聚合物电光波导强度调制器的制备工艺.器件采用DANS (4-dimethylamino-4′nitro-stlibene)聚合物为电光波导材料,由电光波导层、上下介质缓冲层、上下金属电极层构成五层波导结构.对五层光波导各层之间的光学、化学以及微加工工艺的相互兼容性进行了深入研究.采用紫外光漂白方法制备出侧壁光滑的条波导,采用钨丝电晕极化方法对DANS聚合物波导进行有效极化,使其具有电光特性.通过优化器件制备工艺,研制出工作波长为1300 nm的M-Z型电光波导强度调制器原型器件.实验测得器件半波电压约为10 V,调制带宽约为1 GHz.     

PT-PEK-c电光聚合物薄膜的厚度和介电性质

研制了新的PT-PEK-c电光聚合物薄膜材料,用准波导耦合m线方法测量了PT-PEK-c电光聚合物薄膜的厚度,并测量了该聚合物薄膜在1×10²Hz到1×10⁷Hz频率范围内的室温介电常数.测量结果为:厚度d=2.328±0.315μm,在10KHz下,介电常数ε_r＝4023±0.063,介电损耗tanδ＝0.003.     

聚合物电光调制器的热稳定性研究

聚合物波导器件的稳定性是影响其实用化的一个关键问题。聚合物波导器件的热稳定性是由波导层(聚合物材料)的热稳定性决定的。采用侧链型和交联型聚氨酯材料分别制成波导电光调制器研究波导器件的热稳定性,热稳定性的判断依据是通过对聚合物调制器升温过程中测量器件的电光性能的变化。研究结果显示两种器件在常温时具有相同的电光性能,在器件升温过程中发现交联型聚氨酯调制器比侧链型聚氨酯调制器有优异的热稳定性。     

基于电光聚合物的表面等离激元调制器

基于电光聚合物,提出了一种结构简单,尺寸小,效率高的表面等离激元(SPP)调制器.该调制器采用M-Z干涉仪结构的金属波导,金属周围是均匀极化后的电光聚合物,通过在金属波导两臂间加电压对聚合物折射率进行调制,折射率调制再通过M-Z干涉仪结构转化为对金属波导中SPP强度的调制. 通过求解金属波导附近的电场分布,并结合SPP场分布的特点,在理论上说明了这种结构可以通过外加电压有效地调制金属波导输出端SPP的强度,调制所需的半波电压约为2.8V. 关键词： 表面等离激元 电光调制 电光聚合物     

用高斯分布法计算非晶态聚合物聚氯乙烯主转变过程中的动态力学弛豫时间谱分布

对非晶态聚合物聚氯乙烯PVC进行不同频率升温扫描的动态力学弛豫谱测量,发现主转变内耗峰(α峰)峰形及其他峰参数均随频率变化。本文根据连续分布谱的理论讨论PVC主转变内耗峰弛豫时间τ的分布情况,并通过高斯分布时方法,计算出PVC主转变弛豫过程中弛豫时间常数τ₀和激活能△H对弛豫时间τ的贡献权重。指出τ₀和△H在PVC主转变过程中都有明显的分布。     

低阈值极化电压玻璃光波导电光效应的研究

采用热极化技术对掺锗玻璃条形光波导进行极化,通过光纤连接 (单模) 的Mach Zehnder Interferometer 系统测量条形波导内诱导出的电光效应,系统地研究了大气环境下极化条件(极化温度、极化时间、极化电压)对电光效应的影响.结果表明:在最佳极化条件下(406℃、-2.4 kV、20 min),波导内的电光系数为r_TM=0.059±0.001 pm/V, r_TE=0.053±0.001 pm/V,且波导结构中存在一个较低的阈值极化电压(100 V)和阈值极化温度(80℃),此时在波导样品内仍能被激发出可观察的电光效应;实验还发现采用负极化诱导方式产生的电光系数较正极化提高15%左右.     

包层调制的聚合物电光调制器及其理论分析

器件损耗偏高是当前聚合物电光调制器的研究中需要解决的问题之一。在调制器的插损之中,波导传播损耗(包括吸收和散射损耗)的贡献举足轻重。特别是在追求高电光系数的材料同时,传播损耗也将会不可避免地增加。如何改善器件的损耗是聚合物调制器实用化的一个重要课题。为此提出了一种在波导包层中调制光波的设想。理论分析表明,这种方法能够大幅度降低波导传播性能,因而有助于改善器件损耗。由于包层中光波强度比芯层中要弱,因此在包层中调制光波会引起场—模交叠因子的弱化,但是优化计算发现,通过调节波导的尺寸尤其是芯层厚度可以控制交叠因子使其弱化程度降低到最小,在最优的情况下,场一模交叠因子可达0．89。随着波导传播损耗的降低,器件调制区的长度可以做得更长,有助于进一步降低器件的半波电压。     

新型极化聚合物薄膜电光调制器研究

用对硝基偶氮苯类为侧链的键合型聚合物，采用高温电晕极化的方法制作电光薄膜，设计并构造极化聚合物薄膜电光调制器。当通光方向和极化方向平行并且垂直于极化聚合物薄膜的表面时，利用法布里-帕罗（F-P）腔中多光束干涉，可以把通过的光由位相调制转化为强度调制，有利于电光调制器的小型化和高速封装。用这种聚合物薄膜电光调制器测量了锢锡氧化物共面波导上的电信号，并对系统的工作原理进行了分析。实验结果表明，薄膜调制器具有线性电光效应；当F-P腔的精细因子为20（为1.3μm的光），调制电场为1V/μm时，研制的极化聚合物电光调制器的调制深度可达到0.01%。     

钴基金属玻璃感生磁各向异性弛豫时间分布参数的温度依赖关系

从三种钴基金属玻璃的磁场退火感生磁各向异性的弛豫曲线的分析,得出弛豫时间τ的对数正态分布宽度β与温度倒数1/T呈线性关系,分析结果说明,在此弛豫过程中,lnτ₀和激活能E都服从正态分布,前者的分布宽度β₀≈3,后者的分布宽度β_e≈0.34eV。     

基于长周期光栅的有机聚合物高速电光调制器

TN761 2004064380 基于长周期光栅的有机聚合物高速电光调制器=A novel electro-optic polymer modulator based on long period fiber gratings[刊,中]/董小伟(北京交通大学光波技术研究所.北京(100044)),裴丽…∥光学技术.—2004,30(3).—289-291,295 结合长周期光栅的特性和有机聚合物的优点,首次提出了一种新型的基于长周期光栅的有机聚合物高速电光调制器结构。应用多层光波导理论,分析计算了聚合     

紫外胶在聚合物准矩形电光波导中的应用

基于聚合物材料的波导型电光器件对提升光通信网络的带宽容量具有重要的意义。设计并制备了一种基于有机/无机杂化非线性材料的准矩形聚合物电光波导,采用SiO2作为下包层,紫外胶SU-8作为引导芯层,掺有生色团DR1的有机/无机杂化非线性材料DR1/SiO2-TiO2作为电光层,通过优化感应耦合等离子体刻蚀工艺的天线功率、偏置功率和氧气流量,将SU-8同时作为引导芯层和刻蚀工艺的掩模,制备了准矩形电光波导。实验测得波导传输损耗为-3.5 dB/cm。     

Integration of electro-optic polymer modulators with low-loss fluorinated polymer waveguides

We have demonstrated a hybrid Mach-Zehnder optical modulator consisting of a large-core, low-loss fluorinated passive polymer waveguide and an electro-optic (EO) polymer waveguide. The combination exhibits low fiber coupling loss to the passive waveguide and reduced transmission loss because the EO polymer waveguide is used only in the active region. The two waveguides are connected by vertical tapers that permit low-loss adiabatic coupling between the two modes. The half-wave voltage and the insertion loss of the fabricated modulator are 3.6 V and 6 dB, respectively, at a wavelength of 1.55 microm . The estimated coupling loss with the standard single-mode fiber is ~0.5 dB.     

Wave-field formation in a hollow x-ray waveguide

Diffraction and refraction phenomena at the entrance of a hollow x-ray waveguide with weakly absorbing dielectric cladding layers are investigated using two independent approaches: (a) analytical and (b) numerical solutions of the wave equation in the paraxial (parabolic) approximation. It is shown that the wave penetrating through the cladding material substantially modifies the wave field near the waveguide entrance. It results in a significant increase of the total energy flux inside the guiding layer and in additional spatial modulation of the electromagnetic field.     

一种基于导模共振的电光调制器研究

实验研究了基于导模共振的反射型电光调制器采用的棱镜耦合方式,在棱镜上面镀有4层膜,依次为银膜下电极-极化聚合物-缓冲层-金膜上电极。对这种衰减全反射（ATR）型的聚合物波导电光调制器进行了视频调制实验,采用静态偏置电压稳定模式同步角方法,结合对入射激光束进行监测,解决了视频调制中激光器噪声对模拟信号调制影响的问题,提高了工作稳定性。实验结果表明：该电光调制器具有良好的线性和较高的灵敏度。     

Low voltage electro-optic polymer light modulator using attenuated total internal reflection

An improved electro-optic (EO) polymer light modulator based on attenuated-total-internal-reflection (ATR) is demonstrated. The modulator consists of a prism–metal–EO-polymer–metal multilayer structure. An applied electric field across the EO polymer layer electrically modulates the energy coupling efficiency of incoming light into guided wave resonance at fixed angles. Compared with conventional ATR modulators based on surface plasmon resonance, the driving voltage for this modulator has been greatly reduced because of the newly chosen working interior angle. It also offers advantages in terms of insertion loss and aperture size over other techniques for the amplitude modulation of a collimated light beam.     

Numerical model of the polymer electro-optic waveguide

A numerical design model is presented for the polymer waveguide in an electro-optic modulator. The effective index method is used to analyze the height of the core waveguide and rib waveguide, an improved Marcatili method is presented to design the rib waveguide width in order to keep the strong single mode operation and have a good match with the standard fiber. Also, the thickness of the upper cladding layer is discussed through calculating the effective index of the multilayer planar waveguide structure has been obtained by setting the optical loss due to the metallic absorption to an acceptable value (<0.1 dB/cm). As a consequence, we take the EO polymer waveguide structure of UV15:CLD/APC:UFC170 as an example, an optimized design is reported.     

Electrodynamic properties of a waveguide with layered-periodic walls

We study a waveguide with layered-periodic walls for different relations between the dielectric permittivities of the central (guiding) layer and the superlattice layers. We consider guided propagation in such a waveguide, predict the appearance of surface waves in the guiding layer, and discuss the case where almost all energy is transferred in the periodic walls.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 1, pp. 53–62, January 2005.     

A wide-band polymeric electro-optic modulator array based on unidirectional coupling between multi-mode waveguide array and a vertical configured dumping planar waveguide

A polymeric wide-band electro-optic (EO) modulator array based on unidirectional mode-coupling between the guiding multi-mode waveguide array and a vertical configured planar dumping waveguide was developed. A low insertion loss of <1.7 dB was obtained due to asymmetrically designed guiding waveguide and the dumping waveguide. A modulation depth of 91% was achieved with the device length of 3.5 cm at a low driving voltage of 3.2 V. The employment of the dumping planar waveguide not only provides an efficient way to achieve the unidirectional coupling mechanism, but also effectively confines the light coupled from the guiding waveguides within the planar dumping waveguide. The combination of unidirectional coupling and light confinement effects ensures low cross talk of <22 dB between adjacent guiding waveguides. Since the proposed modulator is based on the unidirectional coupling mechanism, it is intrinsically wide-band. A wide-band operation from 1308 to 1324 nm was experimentally obtained. The unidirectional mode-coupling-based wide-band modulation principle can be readily applied to other wavelengths, such as 1330 and 1550 nm ranges.     

A Novel Electro-Optic Polymer Modulator Based on Long Period Fiber Gratings

A novel high-speed electro-optic (EO) polymer modulator based on long period gratings (LPG) is designed. Using the theory of multi-cladding optical waveguide, we achieved relationship between modulate voltage and LPG’s resonant wavelength.     

Migration polarization in dielectrics and semiconductors

It is shown that during migration polarization the relaxation time is governed by the carrier lifetime in the bound state, by the thickness of the layer through which the migration occurs, and by the drift velocity. An equation is found for ion migration by generalizing the equation for ion-relaxation polarization. Experimental data found by the Ioffe method on the ion mobility in Al₂O₃ are reported and compared with the mobilities obtained by the method of this paper, on the basis of the equation for the relaxation time. Migration polarization must be taken into account in analyzing the mechanism for the excess noise and certain cases of current oscillations in semiconductors, dielectric loss of a relaxation nature, relaxation phenomena in film-type active devices, etc.