由相对工作波长等参数确定单模光纤色散

在理论分析和大量数值计算的基础上,本文提出了由单模光纤的相对工作波长(?)、相对折射率差△和芯半径α确定其色散的近似解析公式。此外,利用本文给出的有关公式还可以计算出单模光纤的传播常数和纤芯中功率流所占比率等重要参数。     

焦磷酸质子交换LiNbO3光波导制备技术研究

采用焦磷酸质子交换技术制备LiNbO3光波导,总结了交换条件、退火工艺和波导特性的实验结果,报告了表面腐蚀情况和单模条件。测量分析了退火前后波导折射率分布的变化,采用循环迭代法拟合折射率分布。结果显示退火前后的折射率分别呈近似阶梯和近似指数的分布,均可用费米函数良好地描述。     

焦磷酸质子交换LiNbO_3光波导制备技术研究

采用焦磷酸质子交换技术制备 ＬｉＮｂＯ３光波导,总结了交换条件、退火工艺和波导特性的实验结果,报告了表面腐蚀情况和单模条件。测量分析了退火前后波导折射率分布的变化,采用循环迭代法拟合折射率分布。结果显示退火前后的折射率分别呈近似阶梯和近似指数的分布,均可用费米函数良好地描述。     

单模光纤组合波导的模型及熔锥工艺

本文首先用理论分析的方法证明了将单模光纤组合波导腰部区域的物理模型简化成等效平行波导的近似模型，必须作弱导近似和弱耦合近似．据此理论在弱熔工艺条件下研制成了高性能的，在１．２４～１．６０ μｍ波长范围内频谱响应平坦的２×２定向耦合器件，其具有哑铃形结构的腰部横截面，满足弱导近似和弱耦合近似的条件．     

用高斯近似计算单模α光纤的色散参数

本文提出了一套计算波导色散参数的新方法。用它检验了两种常用的高斯近似对色散参数计算的影响。並在此基础土,提出了光斑的一个新定义,给出了用它近似计算单模α光纤波导色散参数的简单解析公式及其计算结果,还对一些例子做了比较。     

同时存在横向位移和角度偏差时两平板光波导的连接损耗

用对称平板光波导基模场的高斯近似来计算同时存在横向位移、角度偏差以及波导参数不一样情况两单模平板波导的连接损耗，导出了非常简单的公式，同时也给出了数值计算的实例。     

同时存在横向位移和角度偏差时两平板光波导的连接损耗

用对称平板光波导基模场的高斯近似来计算同时存在横向位移，角度偏差以及波导参数不一样情况两单模平板波导的连接损耗，导出了非常简单的公式，同时也给出了数值计算的实例。     

微纳纤芯/包层结构大模场单模聚合物光纤设计

提出了一种微纳纤芯/包层结构大模场单模聚合物 光纤。建立了光纤结构模型,在非 弱导近似条件下,根据波导理论,分析了微纳光纤的单模和波导特性;讨论了微纳纤芯直径 、 芯/包层折射率差以及包层直径等结构参数对微纳纤芯/包层结构聚合物光纤的模场分布、有 效 模场直径等导波特性的影响。结果表明,在传输波长λ＝650nm、微纳纤芯直径Dcore＝172μm、包层 直径Dclad＝250μm和芯/ 包层折射率差δn=0.128时,可获得有效模场直径达126.56μm和芯内能流比为10.66% 的大模场单模聚合物光纤。     

单模光纤模斑尺寸测量

一、引言单模光纤的模斑尺寸是光纤芯径、折射率分布及工作波长的函数。在弱导单模光纤中,电磁场的径向分布可近似用高斯函数来描述,因而只需要单一参数——模斑尺寸(?)即可表达单模光纤中的电磁场径向分布。模斑尺寸ω_0定义为单模光纤中 HE_(11)模式功率密度下降到最大值的1/e 处的宽度。     

MMI型1.31／1.55umGaAs波分复用／解复用器的研制

利用多模波导的自镜像原理,分析设计了一种能直接与单模光纤相耦合的具有最小循环比的1031/1.55um波长的GaAs/G aAlAs波分复用／解复用器。该器件的输入、输出单模波导和SIE多模波导采用离散谱折射率法进行了优化设计,最后获得了当输入、输出单模波导宽为3um、SIE多模波导宽度和最佳耦合长度分别为18um和5602.8um时,该器件的1.31um和1.55um两个波长的隔离度均在70dB以上,且传输损耗小于0.1 dB.     

On Single-Mode Bandwidth in Rectangular-Groove Guide by Finite Element Method

The single-mode bandwidth in rectangular-groove guides with different dimensions has been studied by finite element method. The actual single-mode bandwidth in a rectangular-groove guide is the same with a rectangular guide with the similiar dimensions. The dominant single-mode transmission in a rectangular-groove guide at millimetric waveband by adjusting the guide dimensions can only be an approximate one.     

Optical directional coupler using deposited silica waveguides (DS guides)

A new optical directional coupler using embedded single-mode glass waveguides is presented. The glass waveguides, called deposited silica waveguides (DS guides), were fabricated by depositing doped glass on a silica substrate after forming grooves by reactive sputter etching. Waveguide transmission loss was measured to be 1.3 dB/cm, and fiber-to-waveguide coupling loss was 0.1 dB. Using a tunable monochromatic light source, 96 percent power transfer or 14 dB isolation was measured. The DS guide directional coupler is compatible with single-mode fiber and is expected to be a useful component for future wavelength division multiplexing transmission systems.     

Surface-acoustic-wave guidance produced by ion implantation in quartz

An increase in the surface-acoustic-wave velocity is produced by ion implantation in quartz (y-cut, x-propagating). A 2.5% relative-velocity increase has been measured at 395 MHz, with 100 keV Li+ ions, the flux being 1016 ions/cm2. Slot acoustic waveguides have been realised at about 100 and 400 MHz by these techniques. Horns were used for matching the launched acoustic beams to the guides. An optical probe has been employed for investigating the spatial distribution of the acoustic power. The 100 MHz guide is 148 ?m wide. The guided-power profile along a section of the guide has been measured. The 6 dB beamwidth is about 230 ?m. The 400 MHz guide is 18 ?m wide, and the propagation loss is about 0.75 dB/?s.     

Groove- and H-Waveguide Design and Characteristics at Short Millimetric Wavelengths

The design of the H guide and groove guide for use in the short millimetric range with relatively low-loss, Iow-dispersion, and single-mode operation is considered. Measurements at 40 and 100 GHz show encouraging characteristics. It is considered feasible to construct components to form complete systems in these guides.     

Basic mode characteristics and the contrast range of the refractive index profile of a W light guide

Characteristics of the modes of a planar five-layer W light guide with different values of the inter-layer refractive index are analyzed. It is shown that, in the case of appropriate selection of the geometrical and optical parameters, W light guides can readily ensure single-mode operation in a broad wave band and necessary field concentration in the large-diameter guiding optical core, as well as, simultaneously, guarantee efficient filtering of leaky modes.     

GaAs/GaAlAs curved rib waveguides

Curved dielectric optical waveguides suffer from radiation loss due to bending. To minimize the bending loss and reduce the radius of curvature, it is necessary to fabricate guides which provide strong optical confinement. This paper gives a brief review of curved waveguide analysis and presents some experimentally measured loss values for GaAs/GaAlAs curved rib waveguides. The rib waveguides, fabricated using ion beam milling, have a large rib height and are tightly guided structures. When corrected for reflection losses and input coupling efficiency, a minimum loss of approximately 3 dB has been achieved for a multimode 90° curved guide with a radius of curvature of 300 μm, and 8.5 dB for a single-mode curved guide with a radius of curvature of 400 μm. It is believed that most of this residual loss is not radiation loss due to bending, but rather scattering loss due to rib wall imperfections.     

A study on the development of transmission-type extrinsicFabry-Perot interferometric optical fiber sensor

The conventional reflection-type extrinsic Fabry-Perot interferometric (EFPI) optical fiber sensor has good sensitivity and resolution compared with other types of optical fiber sensors. However, they have the disadvantage that the distinction of strain direction of EFPI is difficult because of measurement method by only fringe counting. This paper presents the newly developed transmission-type EFPI (TEFPI) optical fiber sensor, which has been improved by additional functions, and whose measuring system differs from that of the reflection-type EFPI optical fiber sensors using a single-mode fiber (SMF) and multimode (MMF) fibers as light guides and reflectors, respectively. The output signal of the TEFPI optical fiber sensor was analyzed with the uniform plane wave-based model, the SMF power distribution-based model and the splice loss-based model; the analyzed signals were then verified experimentally. Based on the results of analysis, the TEFPI optical fiber sensor was fabricated using two single-mode fibers connected to the light source and optical receiver; this was then used in strain measurement. The strain measured by the TEFPI optical fiber sensor was compared with that measured by the electric strain gauge     

Analysis of the propagation properties in an inverted strip dielectric guide

In this paper the conditions are derived which the three lowest modes satisfy respectively in an inverted strip dielectric guide (ISDG). The method of optimal design is dealt with for five parameters selected by the Orthogonal Array Table (OAT), which affect the propagation properties including the single-mode bandwidth, the external field divergence, the conductor and the dielectric losses. Many sets of parameters are presented, for which the ISDG s have optimal propagation properties.     

Dispersion characteristics of broadside coupled dielectric image guide at millimeter wave frequencies

Dispersion characteristics and wave impedance for the even and odd modes of the broad side coupled dielectric image guides are computed by using mode matching techniques. Dispersion curves for broadside image guide are plotted for various dielectric materials and dimensional parameters as a function of frequency. Normalized electric field for dominant electric field component E of TM even and odd modes for various half spacings between two dielectric slabs of broadside coupled image guide have been plotted. Polysterene (∈ r=2.56) and Stycast (∈ r=3.4) have been used as dielectric materials in fabricating broadside coupled image guide. This broadside coupled dielectric guide is very convenient as compared to the other dielectric guides. Since in case of broadside coupled image guide the dielectric slab can be bonded to the side metallic walls using some low loss adhesive material, while in other coupled dielectric guides the dielectric slab have to be supported by some low dielectric constant material (Eccofoam with ∈ r=1.02) to maintain the proper distance of side metallic walls from the dielectric slab. Since this structure is symmetrical, this configuration can be analysed in terms of even and odd mode phase velocities. The difference in these even and off mode phase velocities can be used to determine the coupling between coupled dielectric slab. Various couplers in this configuration can be realised.     

Directional couplers in trapped image guide configuration

Dispersion characteristics and wave impedance of trapped coupled image guides are computed by using mode matching techniques. Dispersion curves for trapped coupled image guide are plotted for various dielectric materials and dimensional parameters. The hybrid directional couplers in the above configuration have been theoretically designed by computing the normalization propagation constant.