Ag-Na离子交换玻璃波导的折射率分布研究

用Ag-Na离子交换技术制备了玻璃平面波导.通过棱镜耦合技术测量了波导的模折射率,用反WKB方法拟合得到了平面波导的折射率分布为高斯分布.发现Ag-Na离子交换的扩散系数与交换时间有关,并且随着交换时间的增加而减小.使用随离子浓度变化的扩散系数求解扩散方程得到了玻璃内部Ag离子浓度分布,并通过SEM谱证实了求解的正确性;使用一次多项式模拟的方法求解折射率变化与Ag离子浓度变化之间的关系,得到了平面波导的折射率分布.与反WKB法只能获得多模离子交换平面波导的折射率分布相比,这种方法可以得到任意扩散时间下折射率变化与Ag离子浓度,可以获得单模平面波导的折射率分布.     

掩埋型离子交换玻璃光波导的变分分析

用变分法对离子交换法制备的掺铒光波导的传播特性进行了分析,推导出了适用于掩埋型离子交换玻璃沟道光波导中场分布传播常量的变分表达式,构建了场分布的厄米-高斯型试探解,在两种不同实验条件下,采用变分法确定了试探解中的待定参量,获得光波导中的场分布,利用传播常量的变分公式和已确定的场分布计算得到了传播常量和有效折射率。计算数据表明:导波区域的有效折射率稍稍地大于限制层的折射率,说明离子交换法制备的波导器件是弱波导;高的辅助退火电场强度和适当的退火时间下,所制备的光波导可以支持更多光模式的传输。该方法计算过程简洁、快速,计算结果与实验结果吻合。     

掺铒玻璃波导放大器中抽运光信号光重叠因子分析

通过分析掺铒(Er3 )玻璃波导放大器(EDWA)的放大增益机理,提出抽运光与信号光光模场分布之间的归一化重叠积分因子(Γ),并引入到掺铒波导放大器增益模拟计算中,使理论模型更切合实际。以Ag -Na 二次离子交换工艺制作的具有埋入型渐变折射率分布的掺铒波导放大器为例,采用数值方法模拟了条形波导截面上的二维折射率分布及抽运光、信号光的光模场分布。计算了不同工艺参量设置下的Γ大小,讨论Γ对放大器增益的影响。结果显示,在二次离子交换制作过程中设置适当工艺参量优化折射率分布,能有效改善波导中抽运光与信号光光模场分布之间的重叠因子,提高掺铒波导放大器的增益。计算结果显示,在一定条件下,Γ从0.5增至0.8,每厘米长度掺铒波导放大器的放大增益可提高近1.5 dB。     

K-Na离子交换单模平面波导的制备及其表征

通过K-Na离子交换技术制备了多模玻璃平面波导.采用棱镜耦合技术测量了波导的有效折射率,用IWKB方法拟合得到K-Na离子交换波导的折射率分布符合高斯分布,由色散曲线得到单模波导的制备条件(即扩散深度范围),从而得出单模波导的离子交换时间范围,制备出单模波导,并通过求解WKB色散方程得出单模波导的表面折射率.用普通数码相机,通过对离子交换平面玻璃光波导传输线进行数字成像,根据传输线上的光强分布拟合出光强传输衰减曲线,计算出单模波导的传输损耗大约为0.4 dB/cm.     

Ag+-Li+离子交换制作Er3+/Yb3+共掺磷酸盐玻璃平面光波导

制备了化学稳定的Er3+/Yb3+共掺的磷酸盐玻璃,并在其中制作了用于光放大器和激光器的平面光波导.这种磷酸盐玻璃的失重速率为4.7×10－5g·cm－2·hr－1,小于Kigre公司商业化的磷酸盐玻璃QX/Er的失重速率.采用Ag+-Li+交换技术制作了平面光波导并用m-线光谱在632.8 nm测量了平面光波导的有效折射率.根据反WKB法得到折射率形貌,计算了离子交换参数如:离子交换深度、表面折射率,折射率改变和扩散系数等.     

玻璃波导及两次离子交换法

本文报道Soda-lime玻璃的Ag~+-Na~+和K~+-Na~+离子交换波导的制备、特性分析;并介绍制作表面折射率元件(例如棱镜、透镜)的两次离子交换法,以及用卢瑟福后向散射谱分析玻璃离子交换后表面层的离子分布轮廓。     

K+-Na+和Ag+-Na+两步离子交换技术制作玻璃基光波导研究

利用K+-Na+和Ag+-Na+两步离子交换得到掩埋型光波导.该方法抑制Ag+-Na+离子交换时产生的Ag+微粒,降低波导损耗,增加波导截面的圆对称性,从而提高光波导器件的性能.用该方法制作了1×8光功分器,其插入损耗平均为10.9 dB.     

K~+-Na~+二次离子交换制作玻璃波导

通过数值计算模拟了K + Na+ 二次扩散玻璃波导的折射率轮廓 ,阐述了利用K + Na+ 二次离子交换的方法 ,在BK7玻璃上制作波导的过程 ,分析了极化率不同的扩散离子对的选择对波导有效折射率变化的影响 ,以及扩散平衡时体积变化对表面折射率的影响 ,描述了扩散引起的波导内部诱导应力变化 设计了测试波导损耗以及波导表面折射率改变的实验装置 ,对尺寸 1 0mm×1 0mm× 1 .5mm和 1 0mm× 5mm× 1 .5mm两组BK7玻璃基片上的玻璃波导进行了测试 ,测试结果与理论吻合较好     

质子交换和热退火LiTaO3光波导特性

本文报道了质子交换ＬｉＴａＯ３光波导层的晶格常数变化、质子浓度分布和折射率分布以及红外吸收谱等的测量方法和结果，并与热退火后的测量结果进行了比较。实验结果表明：热退火处理的光波导其非寻常折射率的增高不依赖于质子浓度。     

气相质子交换LiTaO3光波导及其特性

本文利用苯甲酸气相质子交换技术制备了LiTaO3光波导，测量了Z-切LiTaO3光波导的参数（交换深度d和表面折射率增量△nc）和X-切LiTaO3光波导的红外吸收谱，给出了光波导层的折射率分布，并与液相质子交换热退火光波导的结果进行了比较。实验结果表明：非寻常折射率分布与热退火液相质子交换方法制备的LiTaO3光波导基本相近，但表面非寻常折射率增量（△nc）更大，其折射率分布更接近于高斯型。     

光通信中的玻璃无源器件的制备与研究

本文报道了以高质量的BK7光学玻璃为衬底,通过稀释Ag+-Na+离子交换技术,制备出低损耗的表面条波导,并用近场法测量出条波导的模场分布曲线。给出光纤与波导耦合的失配损耗为0.54dB,条波导传输损耗为0.21dB/cm.以及在此工作基础上,成功地研制了适用于大容量相于光通信系统的1×2和1×4单模波导分束器。     

Numerical study of an ion-exchanged glass waveguide using both two-dimensional and three-dimensional models

A numerical study is carried out to compare the two-dimensional (2-D) case and three-dimensional (3-D) case for the modelling of an ion-exchanged glass waveguide. It is shown that different waveguide widths on the photomask correspond to different ion concentration distributions after an annealing process. A numerical example is presented of two waveguide sections with different widths indicates that due to the abrupt change of the waveguide width, a 3-D theoretical model is required for an accurate prediction of the parameters of ion-exchanged glass waveguides. The good agreement between the modelled and measured results proves that the developed 3-D numerical model can be beneficially utilized in the generalized design of optical devices based on ion-exchange waveguides.     

Evolution of CoSi2 buried structures created by high temperature Co+ ion implantation into Si(1 0 0) during post-implantation annealing

The evolution of buried structures of cobalt disilicide, which are formed in a Si(1 0 0) matrix by 400 keV Co⁺ ion implantation at 875 K substrate temperature with subsequent rapid thermal annealing at 1275 K was studied by cross-sectional transmission electron microscopy (X-TEM). The analysis of identical samples with successive variations of the implanted doses and annealing times allows a detailed observation of the role of defects, created by the ion flux, on the process of ripening and growth of CoSi₂ precipitates. We found that transport of the implanted material along diffusive links leads to the formation of a secondary CoSi₂ distribution between the main layer and the surface. Post-implantation annealing results in the evolution of defects into dislocations, which affects the mobility and therefore the growth of CoSi₂ precipitates. Increasing the annealing time leads to the separate growth of precipitates in each layer. The result is not the formation of a single uniform buried layer because the distance between the individual layers is too large due to a screening effect, which operates during the ripening stage.     

集成光学波导光栅研究进展

报道了20世纪80年代以来,研究组在集成光学波导光栅研究领域的主要工作及研究成果。其中包括集成光学波导光栅的制备研究;若干非线性波导光栅器件研究;高效体相位全息布拉格光栅-光导板的耦合互连;单片集成波导光栅波分复用等。这些研究工作为光通信、光计算、光传感和光学信息处理等应用领域提供小型化、低功耗、超快速全光型器件奠定了技术基础。     

酞菁铜LB薄膜覆盖层光波导的光学双稳特性

利用LB薄膜技术在一定尺寸的钾离子交换玻璃波导上制备了30层四—4—(2、4—二特戊基苯氧基)酞菁铜(简称tapCuPc)Z型LB薄膜,形成覆盖有LB薄膜的四层介质波导.首次报道在室温下采用不同激光脉冲观察覆盖有LB薄膜的光波导片上的光学双稳特性,除去LB薄膜覆盖层后没有观察到光双稳特征.     

Plasmonics: influence of the intermediate (or stick) layer on the efficiency of sensors

This paper reports the formation of Ge nanoclusters in a multi-layer structure consisting of alternating thin films of Ge-doped silica glass and SiGe, deposited by plasma-enhanced chemical vapor deposition (PECVD) and post annealed at 1100 °C in N₂ atmosphere. We studied the annealed samples by transmission electron microscopy (TEM) and Raman spectroscopy. As-deposited and annealed samples were analyzed by secondary ion mass spectroscopy (SIMS). TEM investigation shows that Ge nanoclusters were formed in the as-deposited SiGe layer and the SiGe layer was transformed into a silicon dioxide layer embedded with Ge nanoclusters after annealing. These nanoclusters are crystalline and varied in size. There were no clusters in the Ge-doped glass layer. Raman spectra verified the existence of crystalline Ge clusters. The positional shift of the Ge vibrational peak with the change of the focus depth indicates that the distribution of the stress applied to the Ge clusters varies with depth. SIMS measurements show clearly the dramatic O increase in the as-deposited SiGe layer after annealing. The creation of Ge nanoclusters by the combination of PECVD and annealing makes possible the application in complicated waveguide components. PACS 81.07.Bc; 78.66.Jg; 42.65.Wi     

Ti~+离子注入结合热退火法制备TiO_2纳米薄膜研究

利用金属蒸发真空多弧离子源(MEVVA源)注入机将Ti+离子注入到高纯石英玻璃衬底中,离子注入的加速电压为20 k V,注入剂量为1.5×1017和3×1017ions/cm2,将注入样品在氧气气氛下进行热退火处理,制备了TiO2纳米薄膜。采用光吸收谱、拉曼光谱、X射线光电子能谱、扫描电子显微镜和透射电子显微镜对注入样品进行了测试和表征,分析了TiO2薄膜的形成机理。在热退火过程中衬底中离子注入的Ti原子向外扩散到衬底表面被氧化形成了TiO2。TiO2的形成、晶粒尺寸和晶体结构依赖于热退火温度,而形成TiO2薄膜的厚度主要受离子注入剂量和热退火时间的影响。实验结果表明,该方法制备的TiO2纳米薄膜将有望应用于制备具有光催化、自清洁等特殊性能的自清洁玻璃。     

All-Optical Bistability in Grating Coupling to Nonlinear Waveguide

１ＩｎｔｒｏｄｕｃｔｉｏｎＮｏｎｌｉｎｅａｒｄｉｓｔｒｉｂｕｔｅｄｃｏｕｐｌｉｎｇｔｈｒｏｕｇｈｐｒｉｓｍｔｏｎｏｎｌｉｎｅａｒｐｌａｎａｒｗａｖｅｇｕｉｄｅｈａｓｂｅｎｉｎｖｅｓｔｉｇａｔｅｄａｎｄｔｈｅｃｈａｒａｃｔｅｒｓｏｆｏｐｔｉｃａｌｌｉ...     

Er-Yb co-doped glass waveguide amplifiers using ion exchange and field-assisted annealing

Er³⁺-Yb³⁺ co-doped waveguide amplifiers fabricated using thermal two-step ion-exchange are demonstrated. K⁺-Na⁺ ion-exchange process was first carried out in pure KNO₃ molten bath, and then field-assisted annealing (FAA) was used to make the buried waveguides. The effective buried depth is estimated to be ∼3.4 μm for the buried FAA waveguides. With the use of cut-back method, the fiber-to-guide coupling loss of ∼4.38 dB, the waveguide loss of ∼2.27 dB/cm, and Er³⁺ absorption loss ∼5.7 dB were measured for a ∼1.24-cm-long waveguide. Peak relative gain of ∼7.0 dB is obtained for a ∼1.24-cm-long waveguide. The potential for the fabrication of compact optical amplifiers operating in the range of 1520-1580 nm is also demonstrated.     

Modeling of graded index waveguide fabricated by ion exchange on Er3+ doped glass

A general numerical tool,based on thermal diffusion equation and full-vectorial eigen-mode equation,has been presented for the systematic analysis of graded index channel waveguide fabricated by ion exchange on Er3+ doped glass.Finite difference method with full-vectorial formulation(FV-FDM) is applied to solving the full-vectorial modes of graded index channel waveguide for the first time.The coupled difference equations based on magnetic fields in FV-FDM are derived from the Taylor series expansion and accurate formulation of boundary conditions.Hybrid nature of vectorial guided modes for both pump(980 nm) and signal light(1550 nm) are demonstrated by the simulation.Results show that the fabrication parameters of ion exchange,such as channel opening width and time ratio of second step to first step in ion exchange,have large influence on the properties of waveguide.By optimizing the fabrication parameters,maintenance of monomode for signal light and improvement of the gain dynamics can be achieved in Er3+ doped waveguide amplifier(EDWA) fabricated by ion exchange technique.This theoretical model is significant for the design and fabrication of EDWA with ion exchange technique.Furthermore,a single polarization EDWA,which operates at wavelength from 1528 nm to 1541 nm for HE polarization,is numerically designed.