基于表面等离激元金属—介质—金属结构的超材料吸收器的性质研究
发布时间：2018-12-30 20:15
【摘要】：基于表面等离激元的金属-介质-金属结构超材料,可以将光场高度局域在纳米尺度的中间介质层微腔内,同时在特定的共振频段内具有完美吸收和高增益的近场强度等光学特性,在表面增强分子光谱、太阳能电池、生物传感以及光学吸收器件的设计优化等领域内被广泛应用和研究。本文的研究内容包括：金属-介质-金属周期结构超材料中表面等离激元的物理特性、完美吸收的物理机制以及介质腔局域光场的形成机理和相关应用问题。本论文采用有限元分析法(HFSS)进行了较为系统的研究。本文的具体工作和研究结果主要有：1、新颖地提出了金属-介质-金属结构所形成的“圆柱体介质微腔”的概念并利用数值模拟的方法设计和研究了该结构微腔的光学特性,尤其是准确量化了微腔内的能量密度。在正入射光的条件下,反射最小值(dip)落在中红外区域,通过优化结构参数,使其吸收率接近完美吸收,达到97%。此外,计算数据表明：这种亚波长的多层结构不仅可以将大部分的入射电磁场能量局域在中间介质层,使其能量密度比增益高达到104,并且能够得到较高的品质因子Q,而Q值越大,表明在中红外波段的表面增强分子吸收光谱和特征分子振动模式的共振峰的线宽越窄,也即具有更强的电磁场增强效应。再者,由于该结构的对称性,使其对入射光的极化方向具有不敏感的特性。2、设计了三波段的上层(TOP)为同心圆环的金属-介质-金属结构的完美吸收器,研究了在介质腔内所形成的“双圆柱体介质微腔”的近场增强和吸收特性。通过数值模拟分析和优化,该结构反射最小值(dip)位置落在16.65THz,20.65THz和25.65THz,其吸收率分别为95%,97%和95%,而且通过改变其结构参数,可以独立或同时调制结构的单个或多个共振频率,极大地提高了调制效率和灵活性。经计算,双圆柱体介质微腔内的电磁场能量密度比增益高达10s。此外,由于双微腔结构的对称性,故对入射光的极化方向同样具有不敏感的特性,而上述这些特点使其非常适合作为多共振波段表面增强分子光谱的增强基底。3、研究了基于干涉原理的上层(TOP)为正方形的金属-介质-金属结构的长方体介质微腔内的吸收和近场增强特性。在正入射条件下,通过优化结构参数,可以得到中红外范围内四带吸收共振峰,最大吸收率可达98%,而这四个共振峰对应着干涉驻波的基模和高阶模式,它们的位置和近场强度可以通过改变结构参数(尺寸、介质材料)来进行调制。由于生物化学功能基团指纹谱的位置大部分在中红外波段,因此将结构的共振峰与功能基团的吸收振动峰位相重叠,就可以实现多通道的表面增强红外吸收光谱(SEIRA)。
[Abstract]:Metallic-dielectric-metal structure metallics based on surface isoexcitons can localize the optical field height in nanoscale mesoscale microcavities. At the same time, it has the optical properties of perfect absorption and high gain near field intensity in the specific resonance frequency band, and enhances the molecular spectrum on the surface, solar cells, Biosensor and optical absorption device design optimization are widely used and studied. The contents of this paper include the physical properties of surface isopherons in metallic-dielectric-metal periodic structure supermaterials, the physical mechanism of perfect absorption, the formation mechanism of local light field in dielectric cavity and the related application problems. In this paper, the finite element analysis (HFSS) is used to carry out a systematic study. The main results of this paper are as follows: 1. The concept of "cylindrical dielectric microcavity" formed by metal-dielectric-metal structure is proposed, and the optical properties of the structure are designed and studied by means of numerical simulation. In particular, the energy density in the microcavity is accurately quantified. Under the condition of normal incident light, the minimum reflected (dip) falls in the mid-infrared region. By optimizing the structural parameters, the absorptivity is close to the perfect absorption and the absorption reaches 97%. In addition, the calculated data show that the sub-wavelength multilayer structure can not only localize most of the incident electromagnetic energy in the intermediate dielectric layer, so that the energy density ratio gain is up to 104, and the high quality factor Q can be obtained. The larger the Q value is, the narrower the line width of the absorption spectrum and the resonance peak of the characteristic molecular vibration mode in the mid-infrared band is, that is, the stronger the enhancement effect of electromagnetic field is. Furthermore, due to the symmetry of the structure, it is insensitive to the polarization direction of incident light. 2. A perfect absorber of metal-dielectric metal structure with concentric circular ring is designed for the upper layer (TOP) of three bands. The near field enhancement and absorption characteristics of a "double cylindrical dielectric microcavity" formed in a dielectric cavity are studied. Through numerical simulation analysis and optimization, the minimum reflection (dip) position of the structure falls to 16.65 THZ 20.65 THz and 25.65 THZ, the absorptivity is 95% and 95%, respectively, and by changing its structural parameters, The modulation efficiency and flexibility can be greatly improved by the single or multiple resonant frequencies which can be modulated independently or simultaneously. The calculation results show that the gain of electromagnetic field energy density is up to 10 s. Moreover, due to the symmetry of the double microcavity structure, it is also insensitive to the polarization direction of the incident light, which makes it very suitable for the enhancement of the multiresonance surface enhanced molecular spectra. The absorption and near field enhancement characteristics of a cuboid dielectric microcavity with a metal dielectric structure with a square upper (TOP) based on the interference principle are studied. Under the normal incidence condition, by optimizing the structural parameters, the four-band absorption resonance peak in the mid-infrared range can be obtained, and the maximum absorptivity can be as high as 98. The four resonance peaks correspond to the fundamental mode and the higher-order mode of the interference standing wave. Their position and near-field strength can be modulated by changing structural parameters (dimensions, dielectric materials). Since the position of the biochemistry functional group fingerprint spectrum is mostly in the mid-infrared band, therefore, by overlapping the resonance peak of the structure with the absorption vibration peak of the functional group, the multi-channel surface-enhanced infrared absorption spectrum (SEIRA). Can be realized.
【学位授予单位】：南京师范大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：O441;TB34
[Abstract]:Metallic-dielectric-metal structure metallics based on surface isoexcitons can localize the optical field height in nanoscale mesoscale microcavities. At the same time, it has the optical properties of perfect absorption and high gain near field intensity in the specific resonance frequency band, and enhances the molecular spectrum on the surface, solar cells, Biosensor and optical absorption device design optimization are widely used and studied. The contents of this paper include the physical properties of surface isopherons in metallic-dielectric-metal periodic structure supermaterials, the physical mechanism of perfect absorption, the formation mechanism of local light field in dielectric cavity and the related application problems. In this paper, the finite element analysis (HFSS) is used to carry out a systematic study. The main results of this paper are as follows: 1. The concept of "cylindrical dielectric microcavity" formed by metal-dielectric-metal structure is proposed, and the optical properties of the structure are designed and studied by means of numerical simulation. In particular, the energy density in the microcavity is accurately quantified. Under the condition of normal incident light, the minimum reflected (dip) falls in the mid-infrared region. By optimizing the structural parameters, the absorptivity is close to the perfect absorption and the absorption reaches 97%. In addition, the calculated data show that the sub-wavelength multilayer structure can not only localize most of the incident electromagnetic energy in the intermediate dielectric layer, so that the energy density ratio gain is up to 104, and the high quality factor Q can be obtained. The larger the Q value is, the narrower the line width of the absorption spectrum and the resonance peak of the characteristic molecular vibration mode in the mid-infrared band is, that is, the stronger the enhancement effect of electromagnetic field is. Furthermore, due to the symmetry of the structure, it is insensitive to the polarization direction of incident light. 2. A perfect absorber of metal-dielectric metal structure with concentric circular ring is designed for the upper layer (TOP) of three bands. The near field enhancement and absorption characteristics of a "double cylindrical dielectric microcavity" formed in a dielectric cavity are studied. Through numerical simulation analysis and optimization, the minimum reflection (dip) position of the structure falls to 16.65 THZ 20.65 THz and 25.65 THZ, the absorptivity is 95% and 95%, respectively, and by changing its structural parameters, The modulation efficiency and flexibility can be greatly improved by the single or multiple resonant frequencies which can be modulated independently or simultaneously. The calculation results show that the gain of electromagnetic field energy density is up to 10 s. Moreover, due to the symmetry of the double microcavity structure, it is also insensitive to the polarization direction of the incident light, which makes it very suitable for the enhancement of the multiresonance surface enhanced molecular spectra. The absorption and near field enhancement characteristics of a cuboid dielectric microcavity with a metal dielectric structure with a square upper (TOP) based on the interference principle are studied. Under the normal incidence condition, by optimizing the structural parameters, the four-band absorption resonance peak in the mid-infrared range can be obtained, and the maximum absorptivity can be as high as 98. The four resonance peaks correspond to the fundamental mode and the higher-order mode of the interference standing wave. Their position and near-field strength can be modulated by changing structural parameters (dimensions, dielectric materials). Since the position of the biochemistry functional group fingerprint spectrum is mostly in the mid-infrared band, therefore, by overlapping the resonance peak of the structure with the absorption vibration peak of the functional group, the multi-channel surface-enhanced infrared absorption spectrum (SEIRA). Can be realized.
【学位授予单位】：南京师范大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：O441;TB34
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