PMMA脊形光波导的设计与场分析

利用有效折射率法（EIM）理论设计了有机聚合物脊形光波导结构,并分析光波导中传输的模式场,确定出光波导结构的适宜尺寸范围。光波导结构中分别选用PMMA（聚甲基丙烯酸甲酯）与PDMS（聚二甲基硅氧烷）作为波导层与包层的材料,用光漂白法来实现脊形波导结构。首先利用EIM法分析脊形波导区的宽度与高度之间的关系对归一化色散曲线的影响,以及波导层与包层的折射率匹配的影响,然后又通过分析波导区传输的基模场来讨论传输的损耗问题。研究发现波导结构的脊宽与脊高之比w／d越大,其有效折射率neff越大,而此结构尺寸又需约束在一定范围内,否则将造成很大的传输损耗。     

SOI波导弯曲损耗影响因素的分析

采用有效折射率方法EIM(effective index method)和二维束传播算法（2D-BPM）对SOI (silicon-on-insulator）波导弯曲损耗的几种影响因素进行了分析. 通过模拟发现弯曲损耗随弯曲半径的增大、波导宽度的增加及内外脊高比的减小而减小. 同时，改进波导结构，例如在弯曲波导外侧刻槽可以减小SOI脊形波导的弯曲损耗.     

Application of the spectral index method to laser diode design

The spectral index method (SIM) is compared to the effective index method (EIM) and the beam propagation method (BPM) for the calculation of the optical mode index and mode profile in a prototypical distributed feedback (DFB) rib waveguide laser diode. Modal index is shown to be insufficient as a metric of comparison, so in addition to n_mode , the quantum well filling factor Γ and grating coupling coefficient κ are included in the metric for comparison. SIM is found to yield superior results to EIM and to give results comparable to BPM almost two orders of magnitude faster     

SOI波导弯曲损耗改善方法的研究

采用有效折射率方法EIM(Effective Index Method)和二维束传播算法(2D-BPM)对SOI(Sillcon-on—insulator)波导弯曲损耗的改善方法进行了模拟分析．模拟发现,在波导连接处引入偏移量和在波导外侧刻槽等两种不同方法都能有效减小弯曲损耗,并且后者的效果更明显．同时通过实验获得了验证．对R=16mm、横向位移为70μm的弯曲波导,通过刻槽方法将插入损耗降低了5dB,基本消除了弯曲所带来的附加损耗.     

9.0μm GaAs基量子级联激光器的波导优化

通过转移矩阵法和有效折射率法计算了9.0μm GaAs基量子级联激光器波导的模式损耗和限制因子,从而对其波导结构进行优化.计算中考虑了各外延层的厚度、脊宽和腔长的影响.给出了在较低阈值下节约材料生长时间的各外延层厚度.     

A new method for the calculation of propagation constants and fieldprofiles of guided modes of nonlinear channel waveguides based on theeffective index method

In this paper, an extension of the effective index method (EIM) to waveguiding structures containing ideal or saturable third-order nonlinear materials is presented. By applying separation of variables to the dominant field component, the complete problem is subdivided into two scalar problems in the lateral and transverse direction, as in the case of the normal EIM. Making use of the strong transverse confinement, as observed in most real waveguide structures, the nonlinear index changes of the various transverse sections can be lumped into nonlinear effective indexes of the equivalent layered planar structures. By using these nonlinear effective indexes in self-consistent field calculations in the transverse direction, a complete approximate solution is obtained. In this way, the amount of computational effort required for the calculation of the effective indexes and field profiles of the waveguides can be reduced significantly     

布拉格光纤色散特性的研究

布拉格光纤是由在径向折射率呈周期分布的多层介质圆环构成的一种光纤。由于多层的几何结构特征，布拉格光纤表现出与普通光纤不同的色散特性。引入等效折射率法(EIM)结合多层光波导理论来分析布拉格光纤，对于布拉格光纤的色散特性进行了深入的分析，得到了布拉格光纤色散的比例性质(scaling properties)，并举例说明利用波导色散与结构参量的关系，通过调整布拉格光纤的结构参量，灵活地设计其色散特性。     

Strip Waveguide Directional Coupling Modulator with Equivalent Refractive Index

The equivalent refractive index(ERI) method is employed to analyze the function of the strip waveguide directional coupling modulator(SWM). Through deducing the diagnostic equation of the Enm^x mode of the four--layer media film waveguide equivalent to the SWM,the transmission constant of the symmetrical mode of the positive phase and negative one and the coupling length of powerful transference are obtained. The veracity of ERI is validated with the example of Enm^x basal mode under the condition of comparing the three results of ERI,EIM and Marcatili.     

Design and Characterization of Dielectric-Loaded Plasmonic Directional Couplers

Ultracompact directional couplers (DCs) based on dielectric-loaded surface plasmon-polariton waveguides (DLSPPWs) are analyzed using the effective index method (EIM), with the coupling, both in the parallel interaction region and in- and out-coupling regions, being taken into account. Near-field characterization of fabricated DCs performed with a scanning near-field optical microscope verifies the applicability of the EIM in the analysis and design of DLSPPW-based wavelength-selective DCs. The design approach applicable to a large variety of integrated optical waveguides is developed, enabling the realization of DCs in which optical signals at two different wavelengths are coupled into two separate output channels. The developed approach ensures minimization of the crosstalk and overall DC length via simultaneous adjustment of the waveguide separation and length of the interaction region. As an example, the design of a DLSPPW-based DC for complete separation of telecommunication signals at the wavelengths lambda = 1400 nm and lambda = 1600 nm between two output channels separated by 6 mum is worked out, resulting in the total device length of 52.3 mum. In addition, the design of an ultracompact DLSPPW-based DC waveguide crossing that ensures a very low crosstalk over a large wavelength band in the telecommunication range is considered.     

Effective-index method with built-in perturbation correction forthe vector modes of rectangular-core optical waveguides

The effective-index method (EIM) with built-in perturbation correction is developed for the analysis of the vector modes of general rectangular-core optical waveguides. This method maintains the simplicity and the high efficiency of the conventional EIM, yet produces significantly more accurate results. Numerical examples for a wide range of waveguides are presented to demonstrate the accuracy of the method for the calculation of the propagation constants and the modal birefringence     

低损耗波纹波导的传输特性

为了降低太赫兹波传输的损耗,研究了波纹波导中传输太赫兹波时的损耗特性,得到波纹波导的衰减常数的理论计算公式,在数值计算基础上设计了220 GHz低损耗波纹波导,并通过电磁仿真对数值计算结果进行验证,HE11模式实现了仿真与理论结果的相互吻合。     

220 GHz折叠波导慢波结构的有损参数化模型

建立了自洽的考虑波导璧损耗的折叠波导等效电路模型,用来计算该慢波结构周期TE10模式中各次空间谐波的相速度,耦合阻抗和线衰减系数.分析结果将会用到220 GHz折叠波导返波管一维束波互作用模型的计算中.当微波频率上升到太赫兹波段时,粗糙波导表面电流导致的壁损将不能再忽略不计.进一步研究表明,起振电流和输出功率水平将和损耗特性的计算密切相关.从原有模型发展而来的有损电路模型可以给出更准确损耗估计.建立了折叠波导慢波线三维谐振腔模型来验证本文的等效电路理论,有较好的吻合.采用了该理论导出参数的一维束波互作用模型和三维数值PIC方法同样有很好的一致性.     

弯曲波导损耗的一种分析方法

用射线分析法,分析了折射率渐变弯曲波导损耗的实质。根据有效折射率的变型形式分析了影响弯曲波导损耗的主要因素,并计算了最小弯曲半径及其相对应的损耗。     

有效折射率法的研究

分析了有效折射率法及其计算偏差的产生原因,提出了一种改进方法。这种方法克服了有效折射率法的由计算顺序不同导致的计算结果不一致的问题,并使计算精度有所提高。     

一种新型基片集成波导带通滤波器的设计

基片集成波导是一种具有低差损、低辐射、高品质因数的新型平面导波结构．文中利用基片集成波导结构设计并制作了一种工作于X波段的带通滤波器,该滤波器易与其它微波平面电路集成．实测结果表明,该滤波器的中心频率是9.75 GHz,相对带宽是15.4％,通带内反射系数均小于-15 dB,插入损耗均优于1.5 dB,与仿真结果基本吻合,验证了设计方法的正确性．     

Design of an ultra-compact 3 dB MMI coupler

The design of an ultra-compact SOI-based 1×2 3 dB multimode interference（MMI） coupler is proposed.The symmetric multimode interference structure and deeply-etched parabolically tapered multimode waveguide are used in the device.The length of the device is reduced by about 87% compared with general multimode interference straight couplers.Based on effective index method（EIM） and two dimensional beam propagation method（2D-BPM）,the structure parameters are optimized and the fabrication tolerances are analyzed.The results indicate that the performance of the coupler is deeply affected by the coupler＇s width,etching depth and photolithography alignment error in perpendicular direction.     

大功率矩形软波导的研制

矩形软波导是微波设备和馈线之间连接必不可少的一种器件。为此，我们提出了一种矩形软波导的研制方法，并在理论上进行了较为详细的分析、计算。所制得的波导具有低损耗、小驻波、大功率的特点。此研制方法可作为所有矩形软波导的通用设计。     

圆突－矩形波导缝隙天线

本文给出圆突－矩形波导中主模场分量一种近似构造结果的具体表达式，以及用边界元素法解得的截止波长和变分法确定场表达式中待定幂函数的指数常数的具体数值．在假定波导中仅传输主模场的条件下，利用等效原理导出了圆突－矩形波导曲面上纵向缝隙的谐振电导公式，并给出了实际例子，计算和实测获得较满意的结果．     

ARROW-type polarizer utilizing form birefringence in multilayerfirst cladding

A waveguide polarizer using an ARROW (antiresonant reflecting optical waveguide) structure, of which the first cladding consists of three thin layers, is proposed. Theoretical calculation shows that this polarizer can achieve isolation over 30 dB/cm with an insertion loss of 0.01 dB/cm at 1.3 μm. Isolation of 83 dB/cm with insertion loss of 4.3 dB/cm was experimentally obtained at 0.633 μm. This structure is suitable for the integration of a polarization splitter and photodetector     

中物院高功率THz FEL装置波导的物理设计

针对中物院高功率太赫兹自由电子激光(THz FEL)装置,结合目前FEL实验的实际情况,完成了THz波段波导光腔对光腔品质影响的理论分析和模拟计算,确定了不同频段实验所需合适的波导间隙。理论分析与数值模拟表明,光腔加入波导管后减少了腔损耗,使腔内增益提高约30%。完成了不同波导间隙在不同频段的影响计算,并确定了不同频段合适的波导间隙。进一步考察了波导间隙在14 mm和22 mm时对光腔质量及品质的影响。