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针对海洋环境探测中海水温度的大量程高分辨力测量需求,本文提出并验证了一种基于无芯光纤(NCF)与光纤布拉格光栅(FBG)级联的反射式传感器。传感器的制作过程包括将刻有FBG的单模光纤与带有涂覆层的NCF熔接,之后在NCF的端面上镀金膜形成反射镜,最后将光纤结构封装于毛细管中。其中,无涂覆层的NCF是多模波导,而有涂覆层的NCF可以看作反谐振反射波导,理论分析可知多模干涉和反谐振效应叠加得到输出光谱。由于聚合物涂覆层的热光系数较高,干涉波长的位置随着温度变化发生明显偏移。根据FBG中心波长和干涉波长所在位置,通过对应的拟合曲线可以计算出准确的温度值。实验结果表明,在-6℃~54℃温度范围内,最小可探测温度分辨力为0.000 1℃。该反射式光纤传感器具有加工方便、结构紧凑、灵敏度高等优点,在大范围高分辨力海水温度测量中具有很大的应用潜力。 相似文献
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利用二维正方晶格介质柱型光子晶体(PC),设计了一款由4个线性渐变型微腔和异质结构光子晶体反射器组成的多信道下路滤波器。利用平面波展开法(PWE)以及二维时域有限差分法(2D-FDTD)分析了该异质结构滤波器的工作机制,并进一步探究了微腔参考面与异质结界面之间距离对下路效率的影响。研究表明,滤波器中的异质结反射器可以实现接近100%的反射,从而大幅度地提高了三端口滤波器的滤波效率。设计的多信道滤波器各个通道都能有效地实现下路滤波功能,其信道间隔为10nm,滤波效率均在90%以上,透射谱半高宽均在0.54nm以下,实现了较高的品质因子特性。该滤波器尺寸只有15.15μm×13.91μm,且滤波效率很高,适于在波分复用系统中进行复用与解复用,在未来光路集成应用中具有良好的应用前景。 相似文献
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利用光子晶体环形腔缺陷模与线缺陷波导之间的共振耦合原理,设计了一种由主波导、环形腔和60°弯波导组成的四通道二维三角晶格光子晶体解波分复用系统。通过平面波展开法计算线缺陷波导的能带结构;利用时域有限差分法(FTDT)计算了不同频率的光波在该系统中的传输特性。最后,分析了影响输出效率和品质因子的因素并对该系统进行了改进。分析表明:改变环形腔内介质柱的半径可调节谐振频率,而在主波导末端增加反射介质柱以及改变耦合区域中介质柱的形状可提高各通道的谐振频率光波的透射率。计算结果显示:该系统较好地实现了4个波长的解波分复用,透射率均达90%以上。另外,该系统结构简单,便于加工制造,且体积小,有利于大规模集成。 相似文献
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根据多光束干涉原理,提出了一种基于铌酸锂晶体的游标式级联型可调谐滤波器的设计思想.利用铌酸锂的电光效应,通过调节级联电压,改变光波导的折射率,从而实现调谐滤波的功能.该滤波器设计用于波分复用(DWDM)系统中信道的选择. 相似文献
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应力变化对多层薄膜窄带滤光片透射光谱的影响 总被引:2,自引:2,他引:0
利用薄膜应力公式和弹性力学的小挠度弯曲理论分析了在应力变化情况下,多层薄膜应变与膜厚变化的关系,并建立其数学模型,提出多层薄膜各层厚度变化的不均匀性理论.利用这个模型在应力减小200MPa条件下对138层4腔的100GHz滤光片光谱进行了模拟,与设计值比较发现中心波长增加了0.562nm;0.5dB处的带宽比设计值减小0.124nm;25dB处的带宽比设计值减小0.01nm;谱线矩形化变差;插损也有明显的增加.说明了应力变化引起的光学薄膜厚度变化的不均匀性是引起这种窄带干涉滤光片光谱退化的主要原因之一.实验结果为100GHz的窄带滤光片热处理后中心波长增加0.325nm;0.5dB处带宽减少0.01nm;20dB处带宽增加0.014nm;插损增加,谱线通带变形严重,纹波增大,光谱退化了.实验结果与理论分析一致. 相似文献
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用薄膜光子晶体超晶格概念设计多峰滤光片 总被引:1,自引:0,他引:1
多峰滤光片在光通讯波分复用技术中潜在着特殊的应用。利用薄膜一维光子晶体超晶格的概念,设计了两种薄膜多峰滤光片。第一种是基于两个一维光子晶体迭加的多峰滤光片,它在交叠的禁带上出现多组通带,每组通带又包含着多个透射峰,峰的数目为两个光子晶体的周期数减去1;第二种是在第一个光子晶体的中间插进第二个光子晶体,因而形成三个基本周期的光子晶体迭加,峰的数目主要取决于插入的第三个光子晶体的膜层厚度之比和周期数。讨论了多峰滤光片的通带特性和截止度。 相似文献
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文中基于多层共烧陶瓷基板开展预埋芯片混合集成基板技术的研究。通过对混合集成基板的内应力进行仿真分析,得到了预埋芯片基板工艺中芯片和腔体结构的最佳匹配关系。在多层共烧陶瓷基板腔体中埋置芯片并通过金凸点垂直互连实现电连接。在腔体中填充苯并环丁烯(benzocyclobutene, BCB)介质并将BCB 与多层共烧陶瓷基板表面异质抛光形成平面结构,用于后续薄膜电路工艺的实施。文中详细研究和优化了金凸点芯片垂直互连工艺以及多层共烧陶瓷基板/BCB/Au 异质界面的抛光工艺,制作出了适合后续薄膜工艺的预埋芯片混合集成基板。 相似文献
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The analysis of conductor-backed coplanar waveguide moisture sensor by using numerical method is described. The effective dielectric constant, characteristic impedance and dielectric loss of this multi-layer structure are calculated at various moisture contents with respect to protective layer thickness. The analysis shows that calculated values are drastically affected by a small thickness of the protective layer. The experimental results of the attenuation of sensor at various moisture contents agree reasonably with the theoretical data based on the above analysis. The information available from this study is important for estimating of the dynamic range and optimal design of the sensor. 相似文献
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An accurate and sensitive method is reported to measure the thin-film density of vacuum-deposited, small-molecular organic semiconductor materials. A spectrophotometer and surface profiler had been used to determine the mass and thickness of organic thin film, respectively. The calculated density of tris-(8-hydroxyquinolato) aluminum (Alq(3)) thin film was 1.31+/-0.01 gcm(3). Vacuum pressures and thin-film growth rates are found to have less impact on the thin-film density of organic material. However, the thin-film density of organic material strongly depends on its chemical structure and molecular weight. Specifically, the chemical structure determines the density of organic material that affects the molecular volume and intermolecular stacking. 相似文献
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N. D. Goldina 《Optoelectronics, Instrumentation and Data Processing》2009,45(6):571-575
Analytical formulas for calculating the reflection coefficient of a thin-film metal-dielectric structure at light incidence
angles greater than the critical angle of total internal reflection were obtained using a conducting surface model for a thin
absorbing layer. It is shown that an asymmetric interference pattern of the spectral dependence of the reflection coefficient
has higher sensitivity to changes in the refractive index of the medium. 相似文献
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一种梯形干涉链可调谐光滤波器的设计与研究 总被引:8,自引:4,他引:4
结合Mach-Zehnder干涉原理和多模干涉(MMI)耦合器的散射矩阵,从理论上推导出梯形干涉链可调谐光滤波器(LTOF)输出光场的表达式,采用优化算法搜索出不同级联级数下MMI耦合器的最佳分光比,并分析了衍射阶数和电极长度对LTOF调谐输出性能的制约关系。结果表明,对应最大峰值功率,存在随级联级数增加而增大的最佳分光比;增加级联级数会导致峰值功率和3 dB带宽减小,峰值隔离度增大;电极长度为原电极的1.4倍时,可实现LTOF连续双向宽调谐的功能。通过比较,验证了理论模型及分析方法的正确性。 相似文献
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Optimum Design for Shrink-fit Multi-layer Vessels under Ultrahigh Pressure Using Different Materials 总被引:1,自引:0,他引:1
《机械工程学报(英文版)》2010,(5)
Multi-layer pressure vessels are widely used in every field of high pressure technology.For the purpose of enhancing a vessels' load bearing capacity,a beneficial process like shrink-fit is usually employed.However,few documents on optimum design for multi-layer shrink-fit vessels made of different strength materials can be found,available data are mainly on two-layer vessels.In this paper,an optimum design approach is developed for shrink-fit multi-layer vessels under ultrahigh pressure by using different materials.Maximum shear stress theory is applied as design criteria.The inner and outer radii of a multi-layer vessel,as well as the material of each layer,are assumed to be known.The optimization mathematical model is,thereby,built.Lagrange multipliers method is required to obtain the optimal design formula of wall ratio(ratio of outer to inner radii) of each layer,from which the optimum formulas of shrinkage pressure and radial interference are derived with the superposition principle employed.These formulas are applicable for the optimization design of all multi-layer vessels made of different materials,or same materials.The formulas of the limit working pressure and the contact pressure show that the optimum wall ratio of each layer and limit working pressure are only related to all selected material strength and unrelated to the position of the layer placement in the vessel.However,shrinkage pressure is related to the position of the layer placement in the vessel.Optimization design of an open ended shrink-fit three-layer vessel using different materials and comparisons proved that the optimized multi-layer vessels have outstanding characteristics of small radial interference and are easier for assembly.When the stress of each layer is distributed more evenly and appropriately,the load bearing capability and safety of vessels are enhanced.Therefore,this design is material-saving and cost-effective,and has prospect of engineering application. 相似文献