基于光、电调控的太赫兹人工电磁材料特性研究
发布时间：2018-08-30 12:48
【摘要】：人工电磁微结构的兴起为太赫兹技术走向成熟应用提供了新的发展机遇,特别是功能与特性能够被动态操控的超材料设计已成为太赫兹领域新的研究热点。本文围绕光、电可调控的太赫兹功能器件开展了如下的工作,具体的内容包括:1,通过对太赫兹技术研究范畴与应用价值的介绍总结出当前发展所面临的瓶颈和问题,阐述了主动可调控的功能器件是突破太赫兹技术限制的有效途径,针对本课题中三个主动功能器件的实现,介绍相关用于拟合和解释微结构电磁响应的理论模型、样品制备和具体加工工艺流程和基于波面倾斜技术的光泵太赫兹探测实验系统的设计。2,光控宽带的太赫兹等离子诱导透明超材料的设计与性能测试。该超材料的单元结构是由一根中央的金属棒和环绕其周围的四个U形金属环组成,多个暗模与明模增强的耦合作用导致了宽带的PIT效应,整个结构被制作在光敏感的SOS衬底上,通过对硅的巧妙设计实现了带宽为0.54~0.82THz透明窗口的光开关效应。在对样品软件模拟、样品加工、实验测量的基础上,从耦合的洛伦兹谐振子模型出发得出该器件主动调制的机制归结于光照抑制了充当暗模的四个U形金属环的谐振激发。3,电磁人工微结构近场谐振模式的动态耦合效应研究。通过使用电磁仿真软件CST模拟了由三个不等边长的同心金属方环结构的电磁响应,相邻方环之间的电容耦合导致很强的透射峰和相反的表面电流,整个结构制作在SOS衬底上,光敏的硅嵌入到相邻的方环之间,模拟上通过改变硅的电导率和实验上通过改变光照的能量都实现了耦合谐振峰的动态调制,增强光照能量能够实现由电容耦合向电导耦合的转变,理论上从耦合的洛伦兹谐振模型出发解释了主动调控的机制缘于自身谐振和邻近模式耦合激发的共同受阻。4,基于超表面相位不连续的电控太赫兹分束器研究。该器件的结构周期由8个振幅相等、相位依次相差π/4的开口环形金属孔构成,能够实现带宽为0.48~0.93THz正交偏振的异常透射,不同的频率将沿着不同的角度出射,以n型掺杂的砷化镓层作为基底,与金属结构层之间形成肖特基接触,通过施加反向偏置电压来动态调控异常透射的振幅,调制的深度和速率分别可达46%和3k Hz。基于砷化镓基底电导率变化的CST模拟很好的再现了实验的结果。
[Abstract]:The rise of artificial electromagnetic microstructures provides a new development opportunity for the mature application of terahertz technology, especially the design of metamaterials whose functions and characteristics can be dynamically manipulated has become a new research hotspot in the field of terahertz. In this paper, the following work has been done around the optical and electrically adjustable terahertz functional devices. The specific contents include: 1. Through the introduction of the research category and application value of terahertz technology, the bottlenecks and problems faced by the current development are summarized. This paper expounds that active and adjustable functional devices are an effective way to break through the limitation of terahertz technology. Aiming at the realization of three active functional devices in this paper, the relevant theoretical models used to fit and interpret the electromagnetic response of microstructures are introduced. The sample preparation and processing process and the design of optical pump terahertz detection experimental system based on wave surface tilt technology. The design and performance test of optically controlled wideband terahertz plasma-induced transparent supermaterial. The unit structure of the metamaterial is composed of a central metal rod and four U-shaped metal rings around it. The coupling of several dark modes and the open-mode enhancement results in the broadband PIT effect, and the whole structure is fabricated on a light-sensitive SOS substrate. The optical switch effect with bandwidth of 0.54~0.82THz transparent window is realized by the ingenious design of silicon. On the basis of sample software simulation, sample processing and experimental measurement, Based on the coupled Lorentz harmonic oscillator model, it is concluded that the active modulation mechanism of the device is attributed to the suppression of resonance excitation of four U-shaped metal rings acting as dark modes by illumination, and the study of dynamic coupling effect of near-field resonant modes in electromagnetic artificial microstructures. By using electromagnetic simulation software CST, the electromagnetic response of three concentric metal square rings with different length is simulated. The capacitive coupling between adjacent square rings leads to strong transmission peak and opposite surface current. The whole structure is fabricated on SOS substrate. Guang Min's silicon is embedded between adjacent square rings, and the dynamic modulation of the coupling resonance peak is realized by changing the conductivity of silicon and experimentally changing the energy of illumination. The enhancement of illumination energy can realize the transition from capacitive coupling to conductance coupling. Based on the coupled Lorentz resonance model, the mechanism of active regulation is explained by the mutual hindrance of self-resonance and adjacent mode coupling excitation. The study of electronic terahertz beam splitter based on the discontinuity of supersurface phase is presented. The structure period of the device is composed of eight open annular metal holes with equal amplitude and phase difference 蟺 / 4, which can realize the abnormal transmission of the bandwidth of 0.48~0.93THz orthogonal polarization, and the different frequencies will be emitted at different angles. Schottky contact was formed between n-doped GaAs layer and metal structure layer. The amplitude of abnormal transmission was dynamically adjusted by applying reverse bias voltage. The modulation depth and rate were up to 46% and 3 k Hz., respectively. The CST simulation based on the variation of the conductivity of gallium arsenide substrate reproduces the experimental results well.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O441.4
本文编号：2213112
[Abstract]:The rise of artificial electromagnetic microstructures provides a new development opportunity for the mature application of terahertz technology, especially the design of metamaterials whose functions and characteristics can be dynamically manipulated has become a new research hotspot in the field of terahertz. In this paper, the following work has been done around the optical and electrically adjustable terahertz functional devices. The specific contents include: 1. Through the introduction of the research category and application value of terahertz technology, the bottlenecks and problems faced by the current development are summarized. This paper expounds that active and adjustable functional devices are an effective way to break through the limitation of terahertz technology. Aiming at the realization of three active functional devices in this paper, the relevant theoretical models used to fit and interpret the electromagnetic response of microstructures are introduced. The sample preparation and processing process and the design of optical pump terahertz detection experimental system based on wave surface tilt technology. The design and performance test of optically controlled wideband terahertz plasma-induced transparent supermaterial. The unit structure of the metamaterial is composed of a central metal rod and four U-shaped metal rings around it. The coupling of several dark modes and the open-mode enhancement results in the broadband PIT effect, and the whole structure is fabricated on a light-sensitive SOS substrate. The optical switch effect with bandwidth of 0.54~0.82THz transparent window is realized by the ingenious design of silicon. On the basis of sample software simulation, sample processing and experimental measurement, Based on the coupled Lorentz harmonic oscillator model, it is concluded that the active modulation mechanism of the device is attributed to the suppression of resonance excitation of four U-shaped metal rings acting as dark modes by illumination, and the study of dynamic coupling effect of near-field resonant modes in electromagnetic artificial microstructures. By using electromagnetic simulation software CST, the electromagnetic response of three concentric metal square rings with different length is simulated. The capacitive coupling between adjacent square rings leads to strong transmission peak and opposite surface current. The whole structure is fabricated on SOS substrate. Guang Min's silicon is embedded between adjacent square rings, and the dynamic modulation of the coupling resonance peak is realized by changing the conductivity of silicon and experimentally changing the energy of illumination. The enhancement of illumination energy can realize the transition from capacitive coupling to conductance coupling. Based on the coupled Lorentz resonance model, the mechanism of active regulation is explained by the mutual hindrance of self-resonance and adjacent mode coupling excitation. The study of electronic terahertz beam splitter based on the discontinuity of supersurface phase is presented. The structure period of the device is composed of eight open annular metal holes with equal amplitude and phase difference 蟺 / 4, which can realize the abnormal transmission of the bandwidth of 0.48~0.93THz orthogonal polarization, and the different frequencies will be emitted at different angles. Schottky contact was formed between n-doped GaAs layer and metal structure layer. The amplitude of abnormal transmission was dynamically adjusted by applying reverse bias voltage. The modulation depth and rate were up to 46% and 3 k Hz., respectively. The CST simulation based on the variation of the conductivity of gallium arsenide substrate reproduces the experimental results well.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O441.4
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，本文编号：2213112
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