离散谱折射率法优化设计深刻蚀、单模GaAs/GaAlAs脊形光波导

采用离散谱折射率法对深刻蚀 Ga As/ Ga Al As多层脊形光波导的特性作了详细的理论分析 ,并对所获得的较大截面、低损耗的单模脊形光波导的制作容差性作了进一步的分析 .计算表明 ,用离散谱折射率法获得的单模脊形光波导具有较大的制作容差性 .     

多功能2×2 GaAs/GaAlAs多模干涉型光开关分析

提出了一种基于深刻蚀脊形光波导带模斑转换器的多功能2×2 GaAs/GaAlAs多模干涉型光开关,并用变量变换级数展开法及三维有限差分束传播法对其进行了模拟分析与优化设计.结果表明,通过控制多模波导中央的两段Schottky电极,器件可实现交叉态、直通态及3dB耦合器功能,并有较大的制作容差、较宽的工作带宽,只须一个多模波导,器件结构紧凑.采用深刻蚀脊形光波导能够满足多模干涉型器件的精确自镜像要求,并使输入/输出光波导在单模工作下有较大的横截面,较低的弯曲损耗及较小的耦合串扰.通道末端引入的模斑转换器可方便地与单模光纤连接耦合.     

脊形聚合物光波导中传输模式的演变与结构参数的优化设计

本文以脊形聚合物光波导为例,应用光束传播法(BPM)算法来模拟分析其单模区域、模式在波导传输过程中的演变以及模式输出功率随传输距离的变化趋势等.通过对模拟结果的分析,探讨对聚合物光波导结构参数(脊高、脊宽、脊高比)进行合理、最大性优化的可能性,为设计并制作出满足单模传输的脊形聚合物光波导提供理论依据.     

全硅大断面脊形光波导传播特性的理论分析及实验结果

对当前硅光集成的研究焦点－制备大断面单模脊形光波导的单模条件，用有效折射率法进行分析，也计算了传播常数等性能参数。结果表明，有效折射率法有方法简明、结论确切的优点。它能同时给出单模区、多模区及截止区的条件，已有效指导了ＳＩＭＯＸ及ｎ／ｎ＋外延型两种单模脊形硅光波导的制备。文中最后给出了实验结果。     

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。     

Ge0.05Si0.9／Si脊形光波导的光场分析及设计

利用有效折射率法分析了Ｇｅ０．０５Ｓｉ０．９５／Ｓｉ脊形光波导的光场分布，得到了这种光波导在传输单模时内脊高ｂ，外脊高ｈ和脊宽Ｗ的合理取值，还为其它光波导器件的设计奠定了基础。     

聚合物脊形光波导设计

用5层非对称平面波导理论和等效折射率法(ERIM)分析了金属电极对聚合物脊形光波导横向模式特性及其传输损耗的影响。计算结果表明：在工作波长1．55μm波段,当常规脊形光波导的芯层厚度大于0．8μm、包层厚度大于3．0μm时,才能保证传输损耗的理论极限小于0．1dB／cm;当脊波导刻蚀深度为0.l一0．2μm、对应脊波导宽度为7—5μm时,可满足脊波导横向单模传输。     

硅单模脊形光波导的三维模拟及实测结果

对当前硅光集成技术的热点、制备大断面低传播损耗单模脊形光波导进行了三维理论模拟设计。脊的上覆盖层是空气（大折射率台阶，非对称情况）或纯硅层（对称情况），均能得到符合实际的模拟结果。改变脊形光波导的高宽几何尺寸或折射率分布值，模拟结果呈现单模、双模或更高阶模的电场分布及光强分布。用相应条件指导硅脊形光波导的实际制备，实测结果表明模拟结果是准确的。     

单模GexSi1—x脊形光波导的研制

通过分析和计算，得到了单模ＧｅｘＳｉ１－ｘ脊形光波导内脊高、脊宽和腐蚀满足的关系。实践证明，按照这些关系可以成功设计制作 单模ＧｅｘＳｉ１－ｘ脊形光波导。     

Ge_(0.05)Si_(0.95)/Si脊形光波导的光场分析及设计

利用有效折射率法分析了Ge0.05Si0.95／Si脊形光波导的光场分布，得到了这种光波导在传输单模时内脊高b、外脊高h和脊宽W的合理取值，还为其它光波导器件的设计奠定了基础。     

Compact and Economical MMI Optical Power Splitter for Optical Communication

A 1 X 8 GaAs/GaAlAs optical power splitter based on a MultiMode Interference (MMI) coupler is presented. The input and output single mode waveguides are optimized by the Discrete Spectral Index Method (DSIM) and a moderate square spot on the output in deepetched rib waveguides is obtained. The fabrication tolerance has been analyzed by the Finite Difference Beam Propagation Method (FDBPM). The device was fabricated by the dry etching technique and the near-field output obtained. The device shows polarization-insensitive, large fabrication tolerance, low theoretical excess loss and low power imbalance.     

Single-mode and polarization-independent silicon-on-insulator waveguides with small cross section

The fabrication restrictions that must be imposed on the geometry of optical waveguides to make them behave as single-mode devices are well known for relatively large waveguides, with shallow etch depth. However, the restrictions for small waveguides (/spl sim/1 /spl mu/m or less in cross section) are not well understood. Furthermore, it is usually a requirement that these waveguides are polarization independent, which further complicates the issues. This paper reports on the simulations of the conditions for both single-mode behavior and polarization independence, for small and deeply etched silicon-on-insulator (SOI) waveguides. The aim is to satisfy both conditions simultaneously. The results show that at larger waveguide widths, waveguide etch depth has little effect on the mode birefringence because the transverse-electric (TE) mode (horizontal-polarized mode) is well confined under the rib region. However, at smaller rib widths, the etch depth has a large influence on birefringence. An approximate equation relating the rib-waveguide width and etch depth to obtain polarization-independent operation is derived. It is possible to achieve single-mode operation at both polarizations while maintaining polarization independence for each of the waveguide heights used in this paper but may be difficult for other dimensions. For example, a 1-/spl mu/m SOI rib waveguide with an etch depth of 0.64 /spl mu/m and rib width of 0.52 /spl mu/m is predicted to exhibit such characteristics.     

Large single-mode rib waveguides in GeSi-Si and Si-on-SiO2

Mode-matching and beam-propagation methods are used to analyze single-mode operation of optical GeSi-Si and Si-SiO₂ semiconductor rib waveguides. The waveguide dimensions that allow only the fundamental HE₀₀ or EH₀₀ mode to propagate have been determined. For both material systems, it is found that the rib can be several microns wide and several microns high, thus allowing efficient coupling to single-mode fibers. Numerical examples are given for monomode guiding group-IV materials, but the results apply to III-V rib waveguides. It is shown that single-mode rib guides with large cross sections are feasible as long as the waveguide is at least several millimeters long     

Low-loss, single-mode, organic polymer waveguides utilizingrefractive index tailoring

Low-loss, single-mode optical waveguides have been fabricated from photopolymerizable acrylic monomers. The material system consists of a low-index cladding resin and a high-index core resin. The two resins are miscible so that precise control over the refractive index can be obtained. This allows the fabrication of single-mode waveguides with specific cross-sectional dimensions. One advantage of this is the ability to fabricate waveguides with high coupling efficiencies to other devices such as optical fiber or semiconductor lasers. The materials adhere to a wide variety of substrates and exhibit average waveguide losses of 0.56 dB/cm at 1300 nm for single-mode waveguides. Details of the fabrication procedure, index of refraction tailoring technique, and waveguide loss data are presented     

GaAs single-mode rib waveguides with reactive ion-etched totally reflecting corner mirrors

The fabrication and optical properties of reactive ion-etched, totally reflecting mirrors for single-mode GaAs rib waveguides are described. Low loss and orientation independance make the device useful in integrated optics, in order to increase packing density and to facilitate waveguide to fiber coupling. Results of displacement sensitivity calculations are also shown.     

Phase matched magneto optical single mode rib waveguides based on geometrical adjustments

In this work, we demonstrate via numerical simulation the design rules that must be imposed on the geometry of magneto optical rib waveguides to make them behave as single-mode and phase matched rib waveguides.     

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.     

The single-mode condition for semiconductor rib waveguides withlarge cross section

A comparison of the single-mode condition for semiconductor rib waveguides with large cross section obtained by the effective index method and the corrected formula proposed by Soref et al. [see IEEE Journal of Quantum Electronics, vol. 27, p. 1971, 1991] with experimental data is carried out. It is found that the effective index method is in a better agreement with Rickman's experimental data than the modified version. Moreover a stronger condition is proposed for single-mode design purposes