Optical design of bent rib waveguide with MOS cross-section

We provided a single-mode bent MOS-cross-section rib waveguide design with 0.9 dB/cm bending loss at 25 μm bending radius. The peak position for the TE-like mode was tuned to the gate oxide around which the maximum amount of free carriers are accumulated to optimize the free carrier dispersion effect.     

Hot-embossing fabrication of chalcogenide glasses rib waveguide for mid-infrared molecular sensing

Chalcogenide glasses have shown promise in fabricating mid infrared(MIR) photonic sensing devices due to their excellent optical properties in MIR. In addition, the glass transition temperature of chalcogenide glasses are generally low,making them ideal to create the high-throughput patterns of micro-scale structures based on hot embossing that is alternative to the standard lithographic technology. In this paper, we outline the research progress in the chalcogenide waveguide based on the hot embossing method, and discuss the problems remaining to be solved and the possible solutions.     

Improved bends for two-dimensional photonic crystal waveguides

For two-dimensional photonic crystals involving infinitely long dielectric rods or air-holes on square or triangular lattices, a number of high performance 60° and 90° waveguide bends are obtained by solving optimization problems involving the radii of a few rods or air-holes as the degrees of freedom. In particular, the proposed 60° bends significantly outperform previous designs that insert three or five identical air-holes in the bend. The optimization problems are solved using a recently developed method based on the so-called Dirichlet-to-Neumann (DtN) maps of the unit cells.     

Experimental investigation on submicron rib waveguide microring/racetrack resonators in silicon-on-insulator

In experiment, characteristics of silicon microring/racetrack resonators in submicron rib waveguides have been systematically investigated. It is demonstrated that only a transverse-electric mode is guided for a ratio of slab height to rib height h/H = 0.5. Thus, these microring/racetrack resonators can only function for quasi-transverse-electric mode, while they get rid of transverse-magnetic polarization. Electron beam lithography and inductively coupled plasma etching were employed and improved to reduce sidewall roughness for low propagation loss and high performance resonators. Then, the effects of waveguide dimensions, coupling region design, waveguide roughness, and oxide cladding for the resonators have been considered and analyzed.     

Analysis and design of simple low-loss wide-angle waveguide bends

In this paper a simple low-loss planar waveguide wide-angle bend is proposed and analyzed. The waveguide bend of this work consists of a curved tapered angle such that its tapering can be adjusted for a minimum loss (maximum transmission coefficient) and small dimension of bend. The analysis is done using wide-angle BPM (beam propagation method) type Pade (4,4). The simulated results of different bends show that at the same transmission coefficient the area required for the proposed bends are smaller than those of the abrupt bends.     

Wide-angle low-loss waveguide branching for integrated optics

A new wide-angle, low-loss, symmetrical Y-branch waveguide is proposed. The waveguide configuration utilizes ribs for lateral confinement in the planar guiding region underneath. This Y-branch structure can be fabricated easily without an additional process step. Together with a utilization of the multimode interference effect, a local decrease of the waveguide ridge in the wedge part of the Y-branch reduces the radiation loss. When proper@ designed, the proposed Y-branch has a radiation loss as low as 2.2 dB at a branch angle of 6° with the index difference (Δn/n) as small as 7.1 × 10^-4 at a wavelength of 870 nm in the TE fundamental mode as compared to 12.6 dB for a conventional Y-branch. The proposed method yields corresponding advantages for waveguide designs with a higher Δn/n ratio and can also be adapted in combination with S-branch designs.     

慢光在光子晶体弯折波导中的高透射传播

研究了慢光模式在SOI(silicon-on-insulator)材料光子晶体线缺陷弯折波导中的传输特性. 通过优化波导弯折处的结构参数,慢光模式在光子晶体60°与120°弯折波导中的透射率提高10倍以上,归一化透射率分别达到80%和60%以上. 为了进一步减慢光速,设计了新颖的高Q值耦合腔弯折波导结构,在归一化透射率达到75%的基础上,光波群速度低至c/170(c为真空光速). 研究结果对于增强光子晶体的慢光效应,提高光子晶体慢光器件的微型化和集成化都有一定的积 关键词： 光子晶体 慢光 弯折波导 透射率     

Nanohybrids investigation by waveguide SNOM illumination mode

We demonstrate how optical waveguides can serve as a high resolution illumination source to image hybrid nano-objects in near field optical microscopy. Nanohybrid particles deposited on the surface of glass waveguides are imaged in terms of topography, scattering and fluorescence.     

Integrated waveguide sensor utilizing organic photodiodes

We present a novel optical sensor platform, combining monolithically integrated ring‐like sensor waveguides together with ring‐shaped thin‐film organic photodiodes (OPDs) on one substrate. The OPDs serve as integrated light detectors, simplifying the detection system by minimizing the number of required optical components. The waveguide structures, including a means of coupling light in and out of the waveguides, serve as sensing elements. The functionality of the concept is demonstrated by an integrated carbon dioxide sensor, utilizing absorbance as sensing principle. The integrated optical sensor platform is suitable for the parallel detection of multiple parameters in a single sensor chip using sensor arrays. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

聚合物Mach-Zehnder脊形波导的优化设计

利用变分有效折射率法计算了TE基模和高阶模的光场分布,计算结果表明,该方法计算量小,精度高,为聚合物集成光电子器件中脊形光波导的理论分析与优化设计提供了简单高效的途径。利用有限差分束传播法对Mach-Zehnder波导的传播及损耗特性进行了理论分析,得到了不同Y分支角、波导宽度、波导间距时波导传输功率与距离的关系,优化得到的结构参数为：Y分支角1.1°,脊宽5 μm,波导间距20 μm。     

聚合物Mach-Zehnder脊形波导的优化设计

 利用变分有效折射率法计算了TE基模和高阶模的光场分布,计算结果表明,该方法计算量小,精度高,为聚合物集成光电子器件中脊形光波导的理论分析与优化设计提供了简单高效的途径。利用有限差分束传播法对Mach-Zehnder波导的传播及损耗特性进行了理论分析,得到了不同Y分支角、波导宽度、波导间距时波导传输功率与距离的关系,优化得到的结构参数为：Y分支角1.1°,脊宽5 μm,波导间距20 μm。     

光子晶体平面波导与脊波导高效耦合技术的研究

利用一维变周期谐振腔阵列和非线性缓变边界，可以实现光波从脊波导到光子晶体平面波导 （PCW）的高效耦合.基于平面波展开法（PWE）和时域有限差分法（FDTD），深入分析和讨 论了普通脊波导、2D-PCW结构和本征模以及工作模式、缓变边界形状等对耦合效率的影响， 从而得出光波从脊波导到2D-PCW、再返回脊波导的统一图景.指出考虑模式转换和采用缓变 边界条件可以极大提高PCW与脊波导间的耦合效率.对PC-PW边界采用线性和非线性缓变结构 进行了仿真，讨论了边界缓变程度对耦合效率的影响.结果表明，采用模式耦合和PC-PW余弦 缓变边界时的耦合效率在较宽的带宽内超过了95%. 关键词： 光子晶体波导 脊波导 PWE FDTD 耦合边界     

渐变折射率光波导转折点外指数衰减场的推导

证明了渐变折射率光源导转折点外的模场呈简单的指数衰减形式,指数衰减系数可用一恒定的等效折射率定义。     

水平变化双层波导声传播问题的耦合简正波解

为了验证现有模型的精度,导出了全反射下边界双层波导中简正波耦合矩阵的解析表达式,并将其应用到全局矩阵耦合简正波模型(Direct Global Matrix Coupled-Mode)中,使得该模型可以提供水平变化双层波导问题的标准解。文中首先利用COUPLE的简正波及耦合矩阵数值解验证了该简正波及耦合矩阵解析表达式的正确性;其次,采用改进的DGMCM模型求解了双层波导海山声传播损失,结果表明,改进后的DGMCM模型可以非常精确地求解水平变化双层波导问题,可作为求解此类问题的标准模型使用。     

Modal analysis of rib waveguide through finite element and mode matching methods

Two mode solvers based on the finite element and the mode matching methods are compared by way of analyzing rib waveguides. Differences between the normalized propagation constants provided by the two methods are always less than 10^–4 which is at least about one order of magnitude smaller than previously reported values. Results for lossy waveguides and field comparison are also presented.     

梯形截面脊形介质波导导模的分析

本文给出用分区分离变量法计算梯形截面脊形介质波导传插特性与场分布的近似方法.所导出的数学表达式形式简单,物理图象清晰,可用袖珍计算器进行计算,计算工作量较小,所得结果与精确数值计算结果符合较好.     

生物传感中平板光波导模式研究

为提高生物传感探测的灵敏度和响应速度,基于平面光波导理论,运用消逝场原理在生物传感领域的应用,在相同条件下比较了平面波导单模和多模2种模式下消逝场区域能量的大小,并且用VC和Matlab工具模拟论证单模能量高于多模。理论计算表明：单模和多模的荧光效率分别为5.83%和1.75%,在此计算中单模的荧光效率比多模的高。因此,在生物传感及其相关应用中,选用平板光波导的单模模式具有一定的优越性,为实际设计提供了理论依据。     

一种分析三维楔脊形光波导与光纤耦合的方法

和直波导的不同在于，三维楔脊形波导中的光场都是不稳定的.分别对波导-光纤耦合、光纤-波导耦合两种情况，将三维楔脊形波导等效为多段短的直波导，利用束传播法同时对三维楔脊形波导内不稳定的入射、反射场，及它们在传播方向上的偏导进行处理，再用自由空间辐射模法计算透射率和反射率.以SOI楔脊形波导和光纤的耦合为例，验证了该方法的可行性. 关键词： 自由空间辐射模法 束传播法 耦合 透射 楔脊形光波导 绝缘体上硅(SOI)