海上大气负折射现象及其对电波传播影响分析

近地层负折射结构是海洋大气环境中一种少见的异常折射结构,它对电磁波传播的影响与蒸发波导陷获电磁波传播的效果截然相反.利用蒸发波导模型中的伪折射率概念,研究了海洋大气近地层负折射层高度及廓线参数的计算方法,通过仿真手段比较分析了负折射与蒸发波导的差异及其对电磁波传播影响的"反波导"特征,并利用2002年5月福建平潭岛的试验数据对负折射廓线及其对电磁波影响的"反波导"特性进行了验证分析.     

离子交换铒掺杂磷酸盐玻璃波导特性研究

给出有关离子交换铒掺杂磷酸盐玻璃波导的制备以及发光特性的基本结果。用Ag+ Na+ 离子交换在含有适量氧化钠的铒掺杂磷酸盐玻璃上很容易实现低损耗平面波导 ,并且离子交换过程对这种玻璃的光谱特性没有影响。     

Cu离子交换过程对制备玻璃平面光波导特性的影响

用Cu离子交换技术,制备了soda-lime玻璃平面光波导。通过棱镜耦合技术测量了波导的有效折射率,用反WKB方法拟合得到了平面波导的折射率分布。研究发现,离子交换时间和温度2个可控的制备参数对制备的玻璃平面波导特性有较大影响,随着离子交换时间和温度的增加,波导的模式数和波导深度并非随之单调增加,波导模式数随着离子交换时间的增加先增加而后减小,而适当的离子交换时间可以使制备的波导具有最大的模式数和波导深度,且在该条件下增加离子交换温度可以提高Cu离子交换波导的蓝-绿发光强度,宽带发光中心波长在520 nm附近,发光强度取决于样品中Cu+的浓度以及Cu2+的影响。     

离子交换单模玻璃平面波导折射率分布的确定

用Ag-Na离子交换技术制备了玻璃平面波导.求解扩散方程得到Ag离子在玻璃内部浓度分布.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,从而得到了单模平面波导的折射率分布,并验证其与同等实验条件(离子交换时间除外)的多模波导获得的折射率分布函数基本一致.     

玻璃平面波导的热键合制备与界面扩散研究

铒镱共掺磷酸盐玻璃平面波导在散热和抑制非线性效应方面具有独特优势,可开发作为近红外1.5 μm高平均功率固体激光器的增益介质,具有重要意义。文中应用光胶热键合方法制备铒镱共掺磷酸盐玻璃平面波导,研究了预键合阶梯升温过程对键合质量的影响。通过电子探针表面分析（EPMA）得到键合温度和键合时间对键合界面分子扩散层厚度的影响,并根据Fick第二定律,探讨了一维等效假设下的芯层玻璃中的Yb3+扩散机理,建立了热键合过程中的固-固界面分子扩散模型。最终通过选择最优的热处理工艺参数,得到了键合质量良好且键合强度达到11.63 MPa的芯层厚度为100 μm的三明治结构平面波导。     

ENG-MNG介质组合填充矩形波导的TE模传播特性分析

提出了使用磁单负介质和电单负介质组合填充矩形波导结构,在填充波导内电磁场量纵向场法的基础上,应用边界条件得到了双层单负介质填充波导后传播常数解。研究了在不同的介电常数、磁导率和模式下,传播常数、频率和填充介质厚度之间的关系,提出按照一定比例关系和介质参数填充后的波导的带通传播特性。     

铜离子交换单步掩埋BK7玻璃波导的制备与表征

利用Cu离子交换技术制备了BK7玻璃平面光波导,在6328nm波长下,用棱镜耦合技术测量出所制备波导的有效折射率,利用反WKB方法计算并确定了平面光波导的折射率分布,通过对折射率分布进行函数拟合,发现离子交换后的样品折射率分布近似符合改进后的高斯分布,样品的折射率分布似乎是一个掩埋波导的折射率分布,求出所制备玻璃平面光波导在570℃的扩散系数De≈12133×10-14m2s。同时,对所制备波导进行了电子显微镜(EMS)和次级离子质谱(SIMS)测试,得到了铜离子在玻璃表面的浓度分布,从而证明了实验所得到的BK7玻璃平面光波导是掩埋波导。这种掩埋平面波导是由单步Cu离子交换技术得到的。     

脊形单模硅光波导的设计

对脊形单模硅光波导的模式特性进行了理论设计。分析了λ＝１．３μｍ的脊形硅光波导的结构参数及工艺流程。这种光波导的数值孔径和单模光纤匹配，传播损耗低于平面条形硅光波导，文中并对传播损耗作了讨论。     

负折射率材料中的慢光技术研究

首先阐述了负折射率材料的反常传播特性,并简要介绍了通常实现慢光技术的原理。随后分析了利用负折射率材料的波导结构实现慢光的几项关键性研究进展,并对含有负折射率材料的波导结构在室温固体条件下实现慢光的原理进行了总结,进而提出当前利用负折射率材料实现慢光所存在的问题以及研究方向,最后简要介绍了这一最新课题的研究意义和应用前景。     

基于纳米多孔薄膜的对称平面光波导湿度传感器

通过在对称平面玻璃光波导上下表面各制备一层纳米多孔TiO2薄膜,形成了一种简单新颖的光学湿度传感器。其原理为,导波光在平面对称光波导中的传播损失依赖于纳米多孔Ti02薄膜的平均折射率,后者依赖于薄膜内部的水分子吸附量,而薄膜的水分子吸附量随着周围相对湿度的变化而变化,通过实时测量导波光传播损失的变化就能够感知外围的相对...     

分析介质光波导传播特性的Cole—Hopf变换法

采用Cole-Hopf变换法，将平板光波导导模所满足的二阶常微分方程（Helmholtz方程）变换成一阶常微分方程（Riccati方程），用较简单且有效的方法分析导模的特性。给出了多层阶跃型及渐变型平板波导导模的精确解析解和数值解法及实例；给出了非线性平板波导传播特性的数值计算法及实例。     

An analysis of a planar optical directional coupler with a losslessKerr-like coupling medium

The nonlinear all-optically controlled coupling characteristics are studied analytically and numerically for two planar optical waveguides coupled through a lossless Kerr-like slab. The exact dispersion equation for this waveguiding structure is derived in terms of Jacobian elliptic functions. The optical intensity-dependent coupling length is described as a combination of symmetriclike and antisymmetriclike modes of propagation, derived from the nonlinear combination of the independent modes of the structure. A simple analytical formula is derived for the critical power, defined as the power above which the antisymmetric mode disappears and complete energy transfer between the two waveguides is no longer possible. The analysis provides insight into the complicated nature of the waveguiding structure behavior, and it shows one possible approach to solving difficult propagation problems in nonlinear optical waveguides of this or similar configuration     

Birefringent properties of GaAlAs multiple quantum well planaroptical waveguides

Planar GaAlAs optical waveguides in which the waveguide core region is composed of multiple quantum wells are considered. Calculations of optical waveguide dispersion are performed to determine variations in effective refractive indexes for TE and TM modes and in the mode birefringence for large ranges of total waveguide thickness, number, and refractive index of well and barrier layers, and the ratio of well and barrier layer thickness. Ranges of these parameters which yield optical waveguides having unusually high birefringence and optical waveguides supporting single polarization planar propagation only are identified     

Spectral Domain Analysis of Frequency Dependent Propagation Characteristics of Planar Structures on Uniaxial Medium

The propagation characteristics of single and multilayered uniaxial dielectric waveguides and planar structures on uniaxial medium can be determined by utilizing Hertzian potentials along the optical axis. The electric and magnetic Hertzian potentials, having components along the optical axis only, lead to TM and TE modes, respectively, with respect to that axis. The dyadic Green's function in Fourier transform domain (immittance matrix) required to solve for the propagation characteristics of planar structures on uniaxial medium are derived for all three orientations of the optical axis. The immittance matrix for all three cases is in the same form as that for the isotropic medium and hence the known Galerkin's method can be used to solve for the propagation characteristics of the structure.     

激光直写法制备条形光波导中的功率密度阈值

采用溶胶-凝胶法(sol-gel)在Si基SiO2衬底上制备了SiO2-TiO2芯层薄膜,构成了以SiO2为下包层,空气为上包层的平面光波导。利用光纤激光器对平面波导的芯层进行直写,结合后续的化学腐蚀工艺得到了SiO2-TiO2条形光波导,并着重研究了激光直写波导过程中存在的功率密度阈值以及阈值随薄膜预热处理温度的变化关系。研究结果表明,激光直写SiO2-TiO2波导存在起始收缩阈值和烧蚀损伤阈值;随着薄膜热处理温度的提高,两个阈值同时增大,其中损伤阈值的增大趋势要大于收缩阈值;因而薄膜可承受的直写光斑直径变小,所得波导宽度显著减小。最后对直写制得条形光波导的导光性能作了测试分析,验证了波导的三维导光性。     

Numerical analysis of InP/InGaAsP ARROW waveguides using transfermatrix approach

The transfer matrix method is employed to analyze the modal propagation within planar InP/InGaAsP antiresonant reflecting optical waveguides (ARROW) at the operational wavelength of 1.55 μm. The numerical results provide an accurate picture of dispersion and attenuation of both TE and TM polarized waves. Spatial properties of the modes are also investigated and detailed plots of the variation of electric field amplitude with layer thickness are given     

Finite-element solution of planar arbitrarily anisotropic diffused optical waveguides

The finite-element method for propagation in planar anisotropic diffused optical waveguides with arbitrary permittivity tensor is presented. A Galerkin procedure has been introduced to the finite-element formulation, to study both the nonleaky and leaky surface waves. The complex propagation constants are determined as a function of frequency for possible modes of propagation. The accuracy of the method has been checked by calculating the nonleaky and leaky surface waves of Ti-diffused LiNbO3waveguides with Gaussian index profiles. The numerical results of Ti-diffused LiNbO3waveguides with dielectric overlays are also presented and the effects of dielectric overlays on the propagation characteristics for the nonleaky and leaky surface waves are examined.     

Numerical modeling of second harmonic generation in opticalwaveguides using the finite element method

A numerical study of second harmonic generation (SHG) in optical waveguides is presented using the finite element method (FEM) and the Crank-Nicholson split-step procedure. Results are given for a Cherenkov radiation scheme in both planar and channel waveguides. Also presented are results obtained on frequency doubling for guided modes in both planar and channel waveguides, using the quasi-phase-matching scheme     

Optical waveguides in SIMOX structures

Propagation characteristics determined experimentally and theoretically for planar optical waveguides formed in separation by implantation of oxygen (SIMOX) structures are discussed. All samples were found to support both TE and TM modes at both 1.15 μm and 1.523 μm with a lowest propagation loss of 8 dB/cm. This loss was measured at a wavelength of 1.15 μm for the TE₀ mode of a planar waveguide with a 2.0-μm-thick Si guiding layer