超材料器件的能流调控作用研究

发布时间：2018-02-25 23:29

本文关键词： 超常材料近红外微结构耦合器声聚焦透镜单向负折射　出处：《黑龙江大学》2015年硕士论文　论文类型：学位论文

【摘要】：Metamaterial是20世纪末兴起的一种新型的人工结构性材料。其所具有的特异性结构赋予了该类型材料超乎寻常的物理性质,主要表现在其能对诸如电磁波、声波等能量场的完美操控;相对于常规介质材料,该类型材料的另一个优势在于其具有亚波长尺寸的结构周期。因此,超材料的出现为结构微型化、功能超常化的器件制作提供了一个可行的途径。本文首先根据电磁超材料器件的典型设计理论-坐标变换理论,设计了一种近红外光学微结构耦合器,并详细论述了耦合器耦合特性和工作波长、组成耦合器基本单元的电磁参数、基本单元的数量以及耦合器尺寸之间的关系。理论结果表明,通过选定合适的耦合器基本单元,能够实现耦合器效率高达100%全透射;而且,可以通过调节耦合器尺寸,使其满足不同频带的完美透射的需求。其次,从理论方面入手,设计了一种声学超材料聚焦透镜。通过分析组成该聚焦透镜的相位控制单元的声场传输特性,选择透射率高、相位控制精准的结构单元组成声聚焦透镜。仿真结果表明,在相控单元厚度及间距均实现了亚波长尺寸的前提下,上述声聚焦透镜在设计工作频率4167Hz处成功实现了3.29dB增益效果。这对于减小传统声聚焦器件的尺寸,设计出能满足要求的声聚焦透镜具有一定的指导意义。最后,基于等效介质理论,设计了一种声学单向负折射棱镜,并从实验上对其效果进行验证。实验数据表明:在10KHz-20KHz的频率范围内,上述结构均能实现声能流的单向负折射传输。上述设计改善了现有单向传输器件工作频带较窄的特性,在医学超声等需要声能流进行特殊控制的领域具有潜在的应用价值。
[Abstract]:Metamaterial is a new type of artificial structural material which emerged at the end of 20th century. Its special structure endows this type of material with unusual physical properties, mainly because of its perfect manipulation of energy fields such as electromagnetic waves and sound waves. Another advantage of this type of material over conventional dielectric materials is that it has a structural period of subwavelength size. Therefore, the appearance of metamaterials is structural miniaturization. The fabrication of functional supernormal devices provides a feasible way. Firstly, according to the typical design theory of electromagnetic supermaterial devices-coordinate transformation theory, a near infrared optical microstructural coupler is designed. The coupling characteristics and working wavelength of coupler, the electromagnetic parameters of the basic unit of coupler, the number of basic elements and the relationship between the size of coupler are discussed in detail. The theoretical results show that the appropriate basic unit of coupler is selected. It can realize the efficiency of coupler up to 100% full transmission. Moreover, by adjusting the size of coupler, it can meet the requirements of perfect transmission in different frequency bands. Secondly, from the theoretical point of view, An acoustic metamaterial focusing lens is designed. By analyzing the sound field transmission characteristics of the phase control unit which is composed of the focusing lens, the sound focusing lens is composed of a structural unit with high transmittance and precise phase control. On the premise that the thickness and spacing of the phase control unit are subwavelength size, the sound focusing lens has achieved 3.29dB gain effect at the design frequency of 4167 Hz, which can reduce the size of the conventional acoustic focusing device. The design of an acoustic focusing lens that can meet the requirements is of certain guiding significance. Finally, based on the theory of equivalent medium, an acoustic one-way negative refraction prism is designed. The experimental data show that in the frequency range of 10kHz to 20kHz, the above structure can realize the unidirectional negative refraction transmission of sound energy flow, and the above design improves the narrower band characteristic of the existing unidirectional transmission devices. It has potential application value in fields such as medical ultrasound which need special control of acoustic energy flow.
【学位授予单位】：黑龙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB39

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