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本文设计并制作了基于强限制多模干涉耦合器的2×2 SOI马赫-曾德热光开关.这种光开关采用了深刻蚀结构的多模干涉耦合器和输入/输出波导,较大地提高了干涉耦合器的性能并减少了连接耦合损耗.同时,在调制臂区域采用浅刻蚀结构,保持其单模调制状态.深刻蚀多模干涉耦合器具有优越的特性,在实验中测得不均衡度只有0.03 dB,插入损耗-0.6 dB.基于这种耦合器的新型热光开关,其插入损耗为-6.8 dB,其中包括光纤-波导耦合损耗-4.3 dB,开关时间为6.8 μs. 相似文献
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采用基于密度泛函理论的第一性原理方法研究了丙烷硫醇 (C3H7SH)在Au(111)面五种覆盖度(1/16, 2/16, 3/16, 4/16, 1/3) 下的未解离和解离吸附的结构、能量和吸附性质. 发现丙烷硫醇的倾斜角和吸附能均受覆盖度影响, 计算结果显示丙烷硫醇的倾斜角随着覆盖度的增大减小了6°–10°, 吸附能随覆盖度的增大减小了0.21 eV. 特别针对饱和覆盖度, 研究了三种可能的表面结构: (2√3×2√3 ight)R30°, 2√3×3和(3×3). 发现S–H键未解离时三种表面结构的吸附构型和吸附能基本一致; S–H键解离后, (2√3×2√3 ight)R30°和2√3×3结构的吸附能比以(3×3)结构的吸附能约高0.05–0.07 eV, 说明C3H7S在Au(111)面吸附时, 倾向于形成(2√3×2√3 ight)R30°和2√3×3结构. 此外, 采用DFT-D2方法对饱和覆盖度下C3H7SH分子在Au(111)面的吸附进行了范德华修正, 结果显示分子间相互作用使吸附物和Au表面的距离减小, 该相互作用对吸附能的修正值为0.53 eV, 修正后结果与实验结果接近.
关键词:
第一性原理
覆盖度
表面结构
范德华力 相似文献
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平面波导型对称星型耦合器的优化设计 总被引:2,自引:1,他引:1
通过有限差分波束传播法(FD-BPM)研究了N×N平面波导型星型耦合器的优化设计思想和方法,并通过17×17星型耦合器的模拟设计证明了它的可行性.给出了在输出端引入辅助波导的方法,以提高输出波导阵列的均匀性.并通过模拟计算,分析了圆心缩入程度和锥形区的形状对输出结果的影响.此法也同样适合于N值更大的星型耦合器. 相似文献
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高性能三端口全光纤开关 总被引:5,自引:2,他引:3
提出采用2×2和3×3单模光纤耦合器组合成的马赫-陈德尔干涉仪来制作全光纤开关。解决了在连续熔融拉伸两个耦合器组成马赫-陈德尔干涉仪的过程中,由于干涉的作用而无法监视光功率来控制第二个耦合器的分束比的问题。并且由于是连续熔融拉伸,保证了两条单模光纤干涉臂长度的一致,从而提高了单模光纤马赫-陈德尔干涉仪的性能,使得用其做成的三端口压电陶瓷电控全光纤开关具有宽频带的特性,其最小交调达到30dB,附加损耗为0.23dB。 相似文献
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This paper describes a micro-Mach–Zehnder (M–Z) interferometer used in seismic accelerometer. To achieve high modulation efficiency and a small chip size, a deeply etched ridge waveguide structure is employed, and accordingly a multi-mode interference (MMI) coupler is used as the 1 × 4 power splitter. The result of Beam Propagation Method (BPM) simulation indicates that the phase shift is linearly corresponding to the applied acceleration. 相似文献
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一种新型SOI Mach-Zehnder干涉型电光调制器的设计 总被引:8,自引:8,他引:0
在超紧缩双曲锥形3dB多模干涉耦合器的基础上,设计了一种新的Silicon-on-insulator (SOI) Mach-Zehnder干涉型电光调制器.与传统的Y分支器相比,双曲锥形3dB耦合器的制作容差大,而长度缩短了近30%,使得整个器件的尺寸大幅减小.调制区采用横向注入的PIN结构,模拟结果表明:当外加偏压为0.86V时,器件的调制深度最大,此时注入电流为13.2mA,对应的器件功耗为11.4mW. 相似文献
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In this paper, a novel technique to realize frequency quadrupling in the radio over fiber system is proposed. The frequency quadrupling is achieved by using an integrated Mach–Zehnder modulator (MZM) consisting of a 1 × 4 multimode interference (MMI) coupler and four optical phase modulator arms. Due to the inherent optical splitting ratio and phase relations between the outputs of the MMI coupler, the optical harmonics at + 1 order and ? 3 order are generated corresponding to four times frequency of the microwave drive signal, only by setting the DC bias voltage of the main MZM at the minimum transmission point. That leads to the integrated MZM with reduced complexity compared with the conventional dual-parallel MZM. The effect of the nonideal integrated MZM, including the splitting imbalance and the bias drift, on all the sidebands is also analyzed theoretically. The following simulation results show that the slight deviation of the ideal values would not cause great degradation of the generated optical millimeter-wave signal. 相似文献
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相比于传统的1×N对称型多模干涉(Mult-Mode Interference,MMI)分束器设计,提出了一种新型埋入式弱限制光波导分束器件.它的干涉区及输入输出波导采用倒锥形式,器件尺寸减小,且不均匀性与附加损耗也减小.以1×4的对称型MMI分束器为例,当只对干涉区采用倒锥形结构后,在TE偏振中心波长为1.55 μm时,器件长度减小了500 μm,均匀性增加了0.131 dB,而附加损耗仅增加了0.02 dB,波长响应较传统设计增加了40 nm.在此基础上,又在输入输出臂上也各增加倒锥形结构后,相比于传统设计附加损耗减小了0.02 dB,均匀性增加了0.139 dB,器件长度减小了500 μm.改进后的器件具有优越的容差性.器件采用掺氟型聚合物材料进行优化设计,通过在合理范围内偏离输出波导位置,使输出光强达到最大值. 相似文献
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Self-imaging theory is widely accepted as a good method in designing 1 × N multimode interference (MMI) couplers, but it is also true that self-imaging theory is not suitable for low-contrast structures. An improved self-imaging theory is proposed in this paper for the optimal design of low-contrast 1 × N MMI couplers. The average effective width of MMI waveguide and the average effective propagation constant of MMI waveguide are used as the basis to modify the conventional self-imaging theory. A direct calculation of the average effective width of low-contrast MMIs is presented. We use this approach in the optimal design of a 1 × 4 silica MMI coupler, and the results show that the improved self-imaging theory is more accurate than conventional self-imaging theory for low-contrast structures, the results also show that if the material parameters and the width of an MMI waveguide are fixed, the average effective width of the MMI waveguide will increase with the decrease of the height of the core layer. 相似文献
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The overlapping-imaging effect of one-dimensional (1D) multimode interference (MMI) coupler is widened to study the two-dimensional (2D) MMI coupler. 2D overlapping-image MMI couplers permit uniform and nonuniform 2D power splitting. Analytical formulas are derived for the intensities and phases of the overlapping-images at the end of MMI section. The overlapping-imaging properties in 2D MMI couplers are also concluded. And the guided-mode propagation analysis method is used to confirm the analytical results. 相似文献
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二维限制MMI耦合器自镜像特性 总被引:3,自引:3,他引:0
采用扩展的导模传输分析法,对二维限制多模干涉(MMI)耦合器的自镜像效应进行分析,详细讨论了二维限制多模干涉耦合器的自镜像特性和在两个方向上各自都成完整像的要求,并用三维全矢量非旁轴近似光束传输法进一步验证了分析结果.结果表明,一维限制多模干涉耦合器的自镜像效应在一定条件下,可以拓展到二维限制多模干涉耦合器上.并且在强限制的波导结构中,二维自镜像效应可以看成二个相互垂直、独立的一维自镜像效应的叠加. 相似文献
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P.P. Sahu 《Optics Communications》2007,277(2):295-301
In this paper, a novel MMI coupler, based on general interference, with tapered waveguide geometry has been proposed for reduction of coupling length. The coupling characteristics and power imbalance of the proposed structure are compared with conventional MMI structures by using a mathematical model based on sinusoidal modes. It is seen that the beat length for tapered MMI coupler with angle of taper ∼1.05° is reduced by ∼24% of that of conventional MMI coupler and the coupling characteristics obtained with the mathematical model, match well with those obtained by more sophisticated BPM computer aided design software. The power imbalance for tapered 3 dB MMI coupler is more sensitive to the wavelength than that for conventional 3 dB MMI coupler and variation of power imbalance with fabrication tolerance for both the MMI coupler is almost same. 相似文献
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We report on a thin film InGaAsP laser integrated with a 1 x 4 polymer multimode interference (MMI) splitter on a silicon substrate for planar optical signal distribution. The thin film laser had a threshold current of 40 mA and was endfire coupled to the integrated passive polymer MMI splitter, and the optical signal from the laser was distributed to the four output waveguides of the MMI coupler. The measured loss of the MMI splitter was 0.79 dB. The normalized powers of the four MMI output ports in the integrated system were measured to be 0.823, 0.978, 0.852, and 1. 相似文献
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This paper presents a new design for an insensitive-polarization all-optical switch using 2 × 2 multimode interference (MMI) couplers. The switching structure can operate at central operating wavelength 1550 nm for both polarizations. A nonlinear directional coupler is used to realize the phase shifter and therefore switching mechanism is obtained. The transfer matrix method and beam propagation method are used to design and optimize the whole device structure. 相似文献