射频激励金属-陶瓷结构矩形波导CO2激光器的设计与工艺

通过分析波导激光器中的耦合损耗,给出了金属-陶瓷结构CO2波导激光器的设计方案,并对2 mm×2 mm×140 mm的金属-陶瓷结构RF激励波导CO2激光器进行了实验研究,获得3.39 W的输出功率,效率为6%。该项研究对此类器件的进一步发展提供了技术借鉴。     

低损耗太赫兹镀膜金属波导研究

在研究太赫兹波在镀膜二维平板金属波导传输时,损耗减小的机制和条件,发现只有TM 模式在大间隙的金属镀膜波导传播时,其损耗小于不镀膜的金属波导。利用射线光学方法分析波导尺寸、膜厚度以及膜折射率等参数对TM 模式损耗的影响,获得其损耗最低的优化结构参数。用转移矩阵理论对镀介质膜前后平板金属波导的损耗进行理论计算和分析,当介质为聚乙烯且厚度为0.06mm时,波导的损耗最小。所获结论对于太赫兹波导器件及太赫兹波低损耗波导研制具有较大的意义。     

太赫兹Si/SiGe量子级联激光器波导模拟

波导层结构设计是制备太赫兹(THz)量子级联激光器的关键问题之一.本文基于德鲁得(Drude)模型,利用时域有限差分(FDTD)法,对Si/SiGe量子级联激光器的波导层进行优化设计,从理论上对传统的递变折射率波导、单面金属波导、双面金属波导以及金属/金属硅化物波导横磁模(TM模)的模式损耗和光场限制因子进行了对比分析.结果表明,金属/金属硅化物波导不但可以减小波导损耗,而且有很高的光学限制因子,同时其工艺也比双面金属波导容易实现,为Si/SiGe太赫兹量子级联激光器波导层的设计提供了一定的理论指导.     

太赫兹Si/SiGe量子级联激光器波导模拟

波导层结构设计是制备太赫兹(THz)量子级联激光器的关键问题之一.本文基于德鲁得(Drude)模型,利用时域有限差分(FDTD)法,对Si/SiGe量子级联激光器的波导层进行优化设计,从理论上对传统的递变折射率波导、单面金属波导、双面金属波导以及金属/金属硅化物波导横磁模(TM模)的模式损耗和光场限制因子进行了对比分析.结果表明,金属/金属硅化物波导不但可以减小波导损耗,而且有很高的光学限制因子,同时其工艺也比双面金属波导容易实现,为Si/SiGe太赫兹量子级联激光器波导层的设计提供了一定的理论指导.     

用古斯-亨兴位移研究PMN-PT电光陶瓷的电光效应

根据对称金属包覆电光波导中本征损耗与古斯-亨兴(Goos-Hnchen)位移的理论公式,导出了古斯-亨兴位移与作用于波导两侧电压的二次关系公式。用622μm厚度的四方相铌镁酸铅-钛酸铅(PMN-PT)透明电光陶瓷片作为导波层制备了对称金属包覆波导,测量了古斯-亨兴位移与作用于波导两侧电压的关系曲线,计算了所用透明电光陶瓷片的二次电光系数。实验结果与理论分析一致。     

小尺寸硅绝缘体光波导损耗测量

基于法布里-珀罗(F-P)腔理论建立了一种简单有效的硅绝缘体(SOI)光波导损耗测量方法.该方法采用端面耦合,通过测试波导反射功率谱并利用傅里叶频谱信息,完成波导损耗的测量.推导中指出了无法直接利用反射谱F-P峰峰谷值求解损耗的限制因素.应用该方法实现了对刻蚀深度为750 nm和宽度为1200 nm的SOI脊形波导损耗...     

一种X 波段磁场耦合式波导-微带转换结构

波导-微带转换器是微波集成电路和天馈线系统中的重要器件。结合具体应用,设计了一款新型、宽带磁耦合式波导-微带转换器。和传统结构相比,本设计用双层的贴片结构代替金属块状阶梯脊,通过在贴片上加载金属过孔来展宽转换的带宽;将阶梯状金属贴片和微带探针一体化设计,从而避免了焊接带来的损耗和结构不稳定,并且减小了加工难度,降低了重量和成本。测试结果表明,波导-微带转换器的两个端口在8.85～11.52GHz 的频带内回波损耗小于-15 dB,插入损耗约为0.8dB,均满足应用需求。     

FR4基板金属底板共面波导传输线阻抗特性研究

为了提高基于FR4基板的射频电路板天线端口阻抗匹配的性能,利用FDTD方法对基于FR4基板的金属底板共面波导传输线特性阻抗与端口回波损耗进行了计算.在理论分析的基础上,对FR4基板金属底板共面波导传输线进行了实际的加工,加工的基板厚度为1.5mm,中心导带分别为1mm、1.5mm和1.7mm,槽宽分别为0.2mm、0.3mm和0.4mm.利用矢量网络分析仪在1MHz～3GHz频段内对S11进行了测试,从测试结果可以看出,高频部分与理论计算结果比较一致,3种尺寸的金属底板共面波导传输线回波损耗均在-10dB以下,考虑加工误差与焊接工艺,第3种结构的阻抗匹配性能最好.     

基于MIM结构等离子体波导定向耦合器

理论设计了带有扇环共振微腔的弯曲金属-介质-金属(MIM)波导结构,利用共振微腔结构控制表面等离子体波在扇环直角顶点处的定向传播。通过有限时域差分(FDTD)法计算带有扇环微腔结构的直波导透射率与波长关系,并计算扇环微腔结构与传播波导间的间隔对光学性质的影响,发现此微腔波导结构具有较高的透射率,可以在特定波长位置实现滤波效果。基于上述理论设计三路、四路弯曲波导结构,实现表面等离子体波在弯曲波导处的分束、全反射等定向传输特性。该结构具有极强的光束缚效应,在纳米尺度对光进行传输,解决了光信号的反射、传输问题,在光集成、光通讯、光信息处理等方面有较好的应用前景。     

MDM光波导激发高阶SPP模的传输特性

研究了金属-介质-金属(MDM)型表面等离子体激元(SPP)光波导的电磁特性。理论计算结果表明,对于633nm的TM偏振入射光,当介质膜层厚度小于85nm时,波导中只能激发产生一阶SPP模(基模),其余高阶模全部截止。随着介质膜厚度增加,高阶SPP模逐渐被激发产生。当介质膜层厚度较小时,SPP模的有效折射率的实部随阶数的增加而减小,而虚部则随阶数的增加而增加,SPP基模具有最大传输距离。然而,当MDM波导中的介质层厚度超过0.555μm时,由于三阶SPP模的电磁场主要集中在离金属层相对较远的介质层中,其有效折射率的虚部具有最小值,具有最大的传输距离,而非基模。当入射光波长为633nm介质层厚度为0.9μm时,Ag/SiO2/Ag光波导中三阶SPP模的传输距离达到约150μm。     

The impact of CMP and underlying back-end topographical features on losses in deposited dielectric waveguides

The bending losses in rectangular dielectric waveguides deposited on a chemical mechanical polished (CMP) surface above the metal interconnect/interlayer dielectric stack of a processed Si wafer are modeled and estimated. CMP efficiently removes local topography and microroughness, but leaves long-range surface profile undulations due to variations in the metal pattern density. These surface undulations are then transferred to the waveguides deposited on this surface. A beam propagation method (BPM) waveguide simulation program and an equation for bending loss developed by Marcuse have been used to examine the bending losses seen by waveguides deposited on such a surface. In order to simplify the simulation of the bending losses of the waveguides, the undulations are modeled as a series of arcs, which is shown to be a good approximation. It was determined that under typical conditions, the bending losses may be ignored as they are less than 0.1 dB/cm, which is below the range of typical propagation losses for a straight guide.     

Hybrid modes in proton exchanged waveguides realized in LiNbO3, and their dependence on fabrication parameters

In this paper, we present a relation between material structure, hybrid modes, and propagation losses in proton exchanged (PE) LiNbO₃ waveguides. Rutherford backscattering (RBS) and X-ray diffraction studies are used to show that there are two essential reasons for losses and complex behavior in high δn_e PE waveguides. RBS studies show that using benzoic acid melt temperatures below 300°C leads to distorted waveguide layers and propagation losses higher than several dB/cm. At high temperature, the X-ray studies prove that the crystalline order is preserved, but induced strain leads to biaxial exchanged layers, which results in hybrid modes that can have very high losses. Finally, fabrication parameters allowing the realization of high quality, high δn_e, PE waveguides in LiNbO₃ are identified     

AWG中阵列波导耦合系数的计算

针对阵列波导光栅（AWG）中阵列波导耦合系数的计算问题，提出了基于光束传播方法（BPM）的叠加积分方法的修正方法。将修正前、后的结果与简单叠加积分方法的结果作了分析比较，从而验证了修正方法的正确性。分析了阵列波导之间的耦合对耦合系数的影响，阵列波导间距越小，影响越大。     

半矢量模式求解在光波导弯曲损耗计算中的应用

以柱坐标下的半矢量波动方程为基础,采用基于完美匹配层(PML)边界条件的有限差分方法,对弯曲波导进行模式求解,进而得到波导弯曲引起的辐射损耗.基于计算得到的直弯波导的模场分布,采用二维重叠积分法计算了两者连接时的过渡损耗.计算结果与已有实验结果符合较好.采用该方法,研究了SOI脊型波导的弯曲损耗与波导结构参数之间的关系,并对直弯波导的连接进行了优化.     

An Extension of the Effective Index Method to Analyze Leakage Losses in Rib Type Waveguides

An extension of the effective index method is proposed as a tool to investigate leakage losses in two-dimensional waveguides. The above method, referred to as the Extended Effective Index Method (EEIM), utilizes the Transfer Matrix Technique (TMT) for the calculation of the complex propagation constants. The results show that the EEIM can be applied to conventional rib leaky waveguides as well as to rib ARROW leaky waveguides. The results for rib ARROW waveguides show excellent agreement when compared to those obtained with Finite Element Method.     

Design and fabrication of low-loss polymer waveguide components for on-chip optical interconnection

This paper reports the fabrication and characterization of straight and curved polyimide waveguides for on-chip optical signal distribution in GaAs-based optoelectronic integrated circuits. Polyimide ridge waveguides with propagation losses (at 830 nm) as low as 0.6 dB/cm have been fabricated. S-bends and splitters with low curvature losses and good splitting ratios have also been successfully fabricated and tested. The effects of the material properties and radius of curvature on the optical losses are presented, and the advantages of this polymer technology are discussed.     

Grafted GaAlAs rib waveguides on an InP substrate

Rib waveguides were fabricated on a 1.4 mu m thick GaAlAs epilayer granted on the surface of a semi-insulating InP substrate by epitaxial lift-off. Single-mode waveguides with propagation losses (<7 dB/cm) lower than heteroepitaxially grown counterparts have been achieved. TEM analysis on the GaAlAs/InP interface indicates surface scattering as one of the main loss mechanisms.<>     

Evaluation of loss factor of multilayered inhomogeneous waveguidesfor magnetostatic waves using efficient finite element formalism

An efficient finite-element solution procedure is developed for calculating propagation losses of magnetostatic waves in multilayered inhomogeneous waveguides. The final matrix equation is reduced to a standard complex eigenvalue problem whose eigenvalue corresponds to the complex phase constant itself. Thus, iteration procedures are not necessary and the phase and attenuation constants can be directly obtained by solving a standard eigenvalue equation. The validity of the method is confirmed by calculating propagation losses of magnetostatic surface waves in a single yttrium-iron-garnet (YIG)-film structure. Numerical results for a triple-layered YIG film structure are also presented. It is found that, in the triple-layered structure, propagation losses are highly dependent on the linewidth of the film in which the magnetostatic potential is well confined     

Lattice-Matched GaN–InAlN Waveguides at λ = 1.55 μm Grown by Metal–Organic Vapor Phase Epitaxy

We report on the demonstration of low-loss, single-mode GaN-InAlN ridge waveguides (WGs) at fiber-optics telecommunication wavelengths. The structure grown by metal-organic vapor phase epitaxy contains AlInN cladding layers lattice-matched to GaN. For slab-like WGs propagation losses are below 3 dB/mm and independent of light polarization. For 2.6-mum-wide WGs the propagation losses in the 1.5- to 1.58-mum spectral region are as low as 1.8 and 4.9 dB/mm for transverse-electric- and transverse-magnetic-polarization, respectively. The losses are attributed to the sidewall roughness and can be further reduced by the optimization of the etching process.     

高温对Ge_xSi_(1-x)/Si光波导及材料的影响

用ＧｅｘＳｉ１－ｘ／Ｓｉ亚稳材料在高温下制作了光波导，它的传输损耗为０．８ｄＢ／ｃｍ，比低温工艺的０．５ｄＢ／ｃｍ稍大。并发现ＧｅｘＳｉ１－ｘ／Ｓｉ材料的大量失配位错和一些有趣的现象。