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十字架纤芯thz光纤的研究,十字架纤芯thz光纤的研究study on cross-core terahertz fiber16200字37页摘要 在光谱图中位于微波段和红外波段之间的太赫兹（thz）辐射波，很多特殊的性质，比如低能、透视、宽带等，因此它在生物工程、光谱分析学、成像和通信工程等领域有着广阔的应用前景。太赫兹波在传输介质中的吸收损耗...
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十字架纤芯THz光纤的研究
Study on Cross-core Terahertz Fiber
16200字 37页
摘要 在光谱图中位于微波段和红外波段之间的太赫兹（THz）辐射波，很多特殊的性质，比如低能、透视、宽带等，因此它在生物工程、光谱分析学、成像和通信工程等领域有着广阔的应用前景。太赫兹波在传输介质中的吸收损耗很大，但在干燥空气中的传输损耗几乎为零，所以近些年来，人们致力研究和设计不同纤芯结构的光纤，将尽可能多的太赫兹波能量限制在空气中传输，比如亚波长实芯光纤、空芯光纤、多孔光纤、多孔纤芯带隙光纤等。另一方面，聚合物光纤在传输太赫兹波方面具有很多优势，低成本、低吸收损耗的聚合物种类繁多，设计与制备工艺简单等。因此，关于微结构聚合物太赫兹光纤的设计、制造和特性方面的研究成为太赫兹研究领域的热点。
本论文在系统介绍了太赫兹光纤基础知识和理论研究方法的基础上，设计并分析了一种新型的宽带、低损耗太赫兹光纤——十字架纤芯太赫兹光纤。通过优化光纤结构，使模式能量主要分布在十字架纤芯周围的四个大扇形空气孔中，降低材料吸收损耗；外围的介质圆环将光纤固定，同时避免了外部环境对太赫兹波传输的影响；通过增加纤芯到介质圆环的距离降低了限制损耗，实现了一种在0.44THz—0.84THz频率范围内总损耗低于0.086dB/cm的新型太赫兹波光纤。对所设计的太赫兹光纤进行数值模拟，得到了该光纤的有效折射率、吸收损耗、限制损耗、能量分布随频率变化的曲线，并讨论了光纤内直径、介质层厚度对光纤传输特性的影响。本文提出的太赫兹光纤设计思路和方法，以及软件模拟的具体步骤，对新型太赫兹光纤的设计、特性分析和应用具有重要意义。
关键词：太赫兹波 十字架纤芯 限制损耗 数值模拟
Study on Cross-core Terahertz Fiber
Abstract The terahertz radiation that lies between the millimeter wave and infrared region in the electromagnetic spectrum, has huge potential for application in the field of biotechnology, spectroscopy, imaging, and communication, due to its unique characteristics——low energy, perspectivity, and broadband. Given that the absorption losses in dielectrics at the terahertz range are serious, while the dry air is almost transparent for terahertz wave propagation, many optical-fiber-type guiding designs have been developed with the main aim to force a large part of the terahertz radiation to propagation in air while still confine it to a waveguide, these include solid core subwavelength fibers, hollow-core fibers, porous core fibers, porous-core bandgap fibers.. Moreover, polymer microstructured optical fiber has a good advantage in transmitting the terahertz wave, including the large variety of the low-cost and relatively low absorption loss polymer, easy to design and fabricate. Thus, the design, fabrication and characterization of polymer microstructured optical fiber for applications in terahertz waveband has attracted extensive attention in the field of terahertz technology.
In the basis of introducing the fundamental knowledge and the finite element research method of terahertz optical fiber, a new structure of terahertz fiber with cross-core, broadband and low loss is proposed in this paper. By optimizing the fiber structure,it leads to a significant enhancement of the modal fields in the four big fan-shaped air holes, and as a consequence, reduction in the waveguide losses; using the outer tube cladding to fixed the fiber prevents the disturbance of the surrounding environment; by increasing the distance of core and tube cladding, the confinement loss was decreased,thus we provide a new type of terahertz fiber with a total loss lower than 0.086dB/cm in frequency range from 0.44THz—0.84THz. Make use of the software—COMSOL Multiphysics to carry out the step and programme of the numerical cross-core fiber, we obtain the curves among the effective index, absorption loss, confinement loss and power-percentage in air-holes and clad-background with the change of frequency. This paper provides a basic idea and a effective way to achieve a computer stimulation of the design and application of the new type terahertz optical fiber, and it important for the design, analysis and application of new types optical fiber.
Key words Terahertz wave cross-core fiber confinement loss numerical simulation
目录
第一章 绪论 1
1.1 引言 1
1.2 太赫兹技术 1
1.2.1太赫兹波简介 1
1.2.2太赫兹技术的研究现状 3
1.2.3太赫兹波导器件的研究进展 4
1.3课题研究的目的和意义 4
1.4论文的主要内容 5
第二章 微结构聚合物太赫兹光纤 6
2.1 微结构聚合物光纤技术的发展 6
2.2 几种微结构聚合物光纤简介 6
2.2.1亚波长实芯太赫兹光纤 6
2.2.2亚波长多孔太赫兹光纤 7
2.2.3空芯太赫兹光纤 8
2.3 微结构聚合物太赫兹光纤的损耗机理 10
2.3.1吸收损耗 10
2.3.2限制损耗 10
2.4 光纤色散的简单介绍 11
2.5 太赫兹光纤的封装 11
2.6 有限元法 12
2.7 太赫兹光纤数值模拟的实现步骤 12
第三章 十字架太赫兹光纤的设计及数值模拟 14
3.1 十字架太赫兹光纤的几何结构 14
3.1.1光纤的结构设计 15
3.1.2光纤的导光原理 15
3.2 十字架太赫兹光纤的数值模拟 16
3.2.1COMSOL Multiphysics数值模拟过程 16
3.3 对模拟结果的分析 21
3.3.1介质条厚度d对光纤传输特性的影响 21
3.3.2内直径D对光纤传输特性的影响 24
3.3.5双折射 26
第四章 总结 2..
Study on Cross-core Terahertz Fiber
16200字 37页
摘要 在光谱图中位于微波段和红外波段之间的太赫兹（THz）辐射波，很多特殊的性质，比如低能、透视、宽带等，因此它在生物工程、光谱分析学、成像和通信工程等领域有着广阔的应用前景。太赫兹波在传输介质中的吸收损耗很大，但在干燥空气中的传输损耗几乎为零，所以近些年来，人们致力研究和设计不同纤芯结构的光纤，将尽可能多的太赫兹波能量限制在空气中传输，比如亚波长实芯光纤、空芯光纤、多孔光纤、多孔纤芯带隙光纤等。另一方面，聚合物光纤在传输太赫兹波方面具有很多优势，低成本、低吸收损耗的聚合物种类繁多，设计与制备工艺简单等。因此，关于微结构聚合物太赫兹光纤的设计、制造和特性方面的研究成为太赫兹研究领域的热点。
本论文在系统介绍了太赫兹光纤基础知识和理论研究方法的基础上，设计并分析了一种新型的宽带、低损耗太赫兹光纤——十字架纤芯太赫兹光纤。通过优化光纤结构，使模式能量主要分布在十字架纤芯周围的四个大扇形空气孔中，降低材料吸收损耗；外围的介质圆环将光纤固定，同时避免了外部环境对太赫兹波传输的影响；通过增加纤芯到介质圆环的距离降低了限制损耗，实现了一种在0.44THz—0.84THz频率范围内总损耗低于0.086dB/cm的新型太赫兹波光纤。对所设计的太赫兹光纤进行数值模拟，得到了该光纤的有效折射率、吸收损耗、限制损耗、能量分布随频率变化的曲线，并讨论了光纤内直径、介质层厚度对光纤传输特性的影响。本文提出的太赫兹光纤设计思路和方法，以及软件模拟的具体步骤，对新型太赫兹光纤的设计、特性分析和应用具有重要意义。
关键词：太赫兹波 十字架纤芯 限制损耗 数值模拟
Study on Cross-core Terahertz Fiber
Abstract The terahertz radiation that lies between the millimeter wave and infrared region in the electromagnetic spectrum, has huge potential for application in the field of biotechnology, spectroscopy, imaging, and communication, due to its unique characteristics——low energy, perspectivity, and broadband. Given that the absorption losses in dielectrics at the terahertz range are serious, while the dry air is almost transparent for terahertz wave propagation, many optical-fiber-type guiding designs have been developed with the main aim to force a large part of the terahertz radiation to propagation in air while still confine it to a waveguide, these include solid core subwavelength fibers, hollow-core fibers, porous core fibers, porous-core bandgap fibers.. Moreover, polymer microstructured optical fiber has a good advantage in transmitting the terahertz wave, including the large variety of the low-cost and relatively low absorption loss polymer, easy to design and fabricate. Thus, the design, fabrication and characterization of polymer microstructured optical fiber for applications in terahertz waveband has attracted extensive attention in the field of terahertz technology.
In the basis of introducing the fundamental knowledge and the finite element research method of terahertz optical fiber, a new structure of terahertz fiber with cross-core, broadband and low loss is proposed in this paper. By optimizing the fiber structure,it leads to a significant enhancement of the modal fields in the four big fan-shaped air holes, and as a consequence, reduction in the waveguide losses; using the outer tube cladding to fixed the fiber prevents the disturbance of the surrounding environment; by increasing the distance of core and tube cladding, the confinement loss was decreased,thus we provide a new type of terahertz fiber with a total loss lower than 0.086dB/cm in frequency range from 0.44THz—0.84THz. Make use of the software—COMSOL Multiphysics to carry out the step and programme of the numerical cross-core fiber, we obtain the curves among the effective index, absorption loss, confinement loss and power-percentage in air-holes and clad-background with the change of frequency. This paper provides a basic idea and a effective way to achieve a computer stimulation of the design and application of the new type terahertz optical fiber, and it important for the design, analysis and application of new types optical fiber.
Key words Terahertz wave cross-core fiber confinement loss numerical simulation
目录
第一章 绪论 1
1.1 引言 1
1.2 太赫兹技术 1
1.2.1太赫兹波简介 1
1.2.2太赫兹技术的研究现状 3
1.2.3太赫兹波导器件的研究进展 4
1.3课题研究的目的和意义 4
1.4论文的主要内容 5
第二章 微结构聚合物太赫兹光纤 6
2.1 微结构聚合物光纤技术的发展 6
2.2 几种微结构聚合物光纤简介 6
2.2.1亚波长实芯太赫兹光纤 6
2.2.2亚波长多孔太赫兹光纤 7
2.2.3空芯太赫兹光纤 8
2.3 微结构聚合物太赫兹光纤的损耗机理 10
2.3.1吸收损耗 10
2.3.2限制损耗 10
2.4 光纤色散的简单介绍 11
2.5 太赫兹光纤的封装 11
2.6 有限元法 12
2.7 太赫兹光纤数值模拟的实现步骤 12
第三章 十字架太赫兹光纤的设计及数值模拟 14
3.1 十字架太赫兹光纤的几何结构 14
3.1.1光纤的结构设计 15
3.1.2光纤的导光原理 15
3.2 十字架太赫兹光纤的数值模拟 16
3.2.1COMSOL Multiphysics数值模拟过程 16
3.3 对模拟结果的分析 21
3.3.1介质条厚度d对光纤传输特性的影响 21
3.3.2内直径D对光纤传输特性的影响 24
3.3.5双折射 26
第四章 总结 2..
