基于太赫兹时域光谱技术材料参数提取方法的研究

发布时间：2019-03-04 18:23

【摘要】：近20年,太赫兹科学技术发展迅速,太赫兹波由于其特殊的波段位置和优良的性能,已被广泛应用于工业生产和科学研究领域,太赫兹波与物质之间的相互作用成为研究热点。基于太赫兹时域光谱技术测量并且提取该波段材料的光学特性,是进一步深入研究太赫兹脉冲与物质的相互作用的表征手段,也是目前科研工作者在太赫兹科学与技术研究领域最基本、最普遍、最关键的一部分。本文研究了基于太赫兹时域光谱技术的测量原理和应用,提出了一种改进固体平行型样品材料参数测量精确度的方法。本文的研究工作主要内容和创新点包括:第一部分综述了太赫兹时域光谱系统、三种提取样品材料参数的模式以及近年来国内外采用太赫兹光谱技术研究物质性质的研究现状。第二部分提出了对Duvillaret和Dorney测量方法的改进方案,从理论上分析了不等光程方法提高材料太赫兹波段折射率和吸收系数等参数测量精度的可行性,并进行了实验验证,获得了 0.5-2.5THz频率范围的高密度聚乙烯的折射率和吸收系数。结果显示两种方法测量样品的折射率和吸收系数有较大的差异,不等光程法能更加精确提取材料参数,并可以揭示常规方法无法测得的材料特征吸收峰。第三部分利用两种方法测量了褐煤A、褐煤B、贵州烟煤和木质腐殖酸四种煤炭样品在太赫兹波段的光谱特性。分析了四种煤炭样品在0.5-1.5THz波段的吸收系数、折射率和介电常数等材料参数。本文的主要创新点是基于透射式太赫兹光谱技术提出一种改进提取材料参数新颖的方法——不等光程法,该方法将目前常用的常规法改进,将空置样品时的空气参考信号替换为透过不等厚度的样品的太赫兹信号作为参考信号。对比常规法和不等光程法的理论推导过程,可以明显的看到不等光程法提取的材料参数相比较常规法精确度更加高,操纵更加简单方便,该方法有望为提高太赫兹波段材料的特征光谱数据库做出部分贡献。
[Abstract]:In the last 20 years, terahertz wave has been widely used in industrial production and scientific research because of its special band position and excellent performance. The interaction between terahertz wave and matter has become a research hotspot. Based on terahertz time domain spectroscopy (THz), the optical properties of the materials in this band are measured and extracted, which is a means to further study the interaction between terahertz pulses and matter. It is also the most basic, most common and key part of THz science and technology research. The measurement principle and application based on terahertz time domain spectroscopy (THz) are studied in this paper. A method to improve the accuracy of material parameters measurement for solid parallel samples is proposed. The main contents and innovations of this paper are as follows: in the first part, the terahertz time-domain spectroscopy system, three models for extracting the material parameters of samples, and the research status of terahertz spectroscopy techniques used in the study of material properties at home and abroad in recent years are reviewed. In the second part, an improved method for measuring Duvillaret and Dorney is proposed, and the feasibility of improving the precision of measurement of refractive index and absorption coefficient of THz band by unequal optical path method is analyzed theoretically, and the experimental verification is carried out. The refractive index and absorption coefficient of high density polyethylene (HDPE) with 0.5-2.5THz frequency range were obtained. The results show that there are great differences in refractive index and absorption coefficient between the two methods. The unequal path method can extract the material parameters more accurately and reveal the characteristic absorption peaks which can not be measured by conventional methods. In the third part, the spectral characteristics of lignite A, lignite B, Guizhou bituminous coal and woody humic acid in terahertz band were measured by two methods. The absorption coefficient, refractive index and dielectric constant of four kinds of coal samples in 0.5-1.5THz band were analyzed. The main innovation of this paper is that based on the transmission terahertz spectroscopy, a novel method for extracting material parameters-unequal path method, is proposed. This method improves the conventional method, which is commonly used at present. The air reference signal of the empty sample is replaced with the terahertz signal of the sample with different thickness as the reference signal. Compared with the conventional method and the unequal path method, it can be seen that the material parameters extracted by the unequal path method are more accurate and easy to operate than the conventional method. This method is expected to contribute to the improvement of the characteristic spectral database of terahertz band materials.
【学位授予单位】：山东科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB30;O441

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