微纳结构提高荧光物质发光强度的研究
发布时间：2018-07-26 16:22
【摘要】：随着微纳光子学科的蓬勃发展,各种多功能的微纳光子结构被设计和制备,并在医疗、通信和能源等方面得到应用。增强荧光物质的发光强度是微纳光子结构应用的一个重要方面。LED是照明和显示器件的核心器件。伴随着量子点制备技术的发展,量子点LED被制备出来,它比目前的LED在产生白光方面更有优势,因此研究增强量子点的荧光有现实的意义。同时,在生命科学领域,提高荧光检测的灵敏度的意义重大,而提高荧光物质的发光则是提高检测灵敏度的重要前提。由于微纳结构的小尺寸,外界电磁波与其作用时,能量密度主要集中在微纳结构的表面附近范围。而实际的医学应用中,特别是对于体外细胞的测量,往往需要将荧光物质置于结构的远场范围内。因此增强荧光物质在距离结构远场区域的远场荧光对于在生物传感方面有十分有必要。基于以上的分析,为了提高量子点的发光光强并应用于量子点白光LED,作者设计了一种周期性多层异质结构。采用严格耦合波分析法和有限时域差分法模拟了周期数、各层厚度、入射角度对反射率的影响,以及几个特定波长的电场分布。实现了多个高反射波段,分别对应着紫外光、紫光、蓝光、青光和红光,且高反射波带可调节。并且实验验证了该结构可以实现量子点的荧光增强。其增强机理为结构对入射光的多次反射和干涉效应。为了提高荧光物质在器件的远场发光,设计了一种半圆柱形金属微米通道。研究了荧光激发过程中,两种偏振模式下,在结构空间相同一点(Point A)的时域和频域变化。通过研究时域图发现,各个结构都比对比的玻璃结构更容易使得上转化粒子被激发;通过研究频域图发现,在激发光980 nm(上转换粒子的激发光波长)时,半圆形的金属凹槽结构在Point A点光最强。研究了荧光发射过程,将荧光物质放置在空间中相同位置(Point A),测量远场的荧光强度,发现半圆柱形的金属凹槽结构的远场荧光最强。测量波长为617 nm时,几种典型结构的电场分布图,以及荧光物质放在不同位置时,半圆形金属凹槽结构的电场分布图。并通过研究荧光物质在该结构的不同位置的远场荧光强度。最终结果表明,该结构与玻璃平板结构相比,实现了处于其距离结构底部4.4微米处的上转换纳米粒子的远场荧光增强倍数为8.25。其增强机理为在结构样品区中复杂的散射、相干干涉和光耦合模式从而导致了荧光的增强。设计了一种新型微腔结构,基底采用的是五个周期的Si和SiO2,并水平方向放置两个Ag的反射板。计算了该结构和其它三个结构的荧光发射过程,并对比了远场的发光光强,证明了该结构具有荧光增强效应。通过对波长为656 nm处的电场分析,可以知道荧光物质与结构的耦合模式较强。
[Abstract]:With the rapid development of micro-nano photonics, a variety of multi-functional micro-nano photonic structures have been designed and fabricated, and have been applied in medical, communication and energy fields. Enhanced luminescence intensity of fluorescent materials is an important aspect of the application of micro-nano photonic structure. Led is the core device of lighting and display devices. With the development of quantum dot preparation technology, quantum dot LED has been prepared, which is superior to the current LED in the generation of white light. Therefore, it is of practical significance to study the enhancement of quantum dot fluorescence. At the same time, in the field of life science, it is very important to improve the sensitivity of fluorescence detection, and to improve the luminescence of fluorescent substances is an important prerequisite to improve the sensitivity of detection. Due to the small size of micro / nano structure, the energy density is mainly near the surface of micro / nano structure when external electromagnetic waves interact with it. In practical medical applications, especially for the measurement of cells in vitro, fluorescent substances often need to be placed in the far-field range of the structure. Therefore, it is necessary to enhance the far field fluorescence of fluorescent substance in the far field region of the structure. Based on the above analysis, in order to improve the luminous intensity of quantum dots and apply to white LED, a periodic multilayer heterostructure is designed. The effects of period number, thickness of each layer and incident angle on reflectivity and electric field distribution of several specific wavelengths are simulated by means of strictly coupled wave analysis and finite-time-domain difference method. Several high reflectance bands are realized, corresponding to UV, UV, blue, blue and red, respectively, and the high reflectance band is adjustable. The experimental results show that the structure can enhance the fluorescence of quantum dots. The enhancement mechanism is the multiple reflection and interference effect of the structure to the incident light. In order to improve the far-field luminescence of the device, a semi-cylindrical metal micron channel is designed. The time-domain and frequency-domain variations of (Point A) at the same point in structure space in two polarization modes during fluorescence excitation are studied. By studying the time domain map, it is found that each structure is easier to excite the upconversion particle than the contrast glass structure, and the frequency domain diagram shows that when the excitation light is 980 nm (the excitation wavelength of the up-converted particle), The semicircular metal grooves have the strongest light at Point A. The fluorescence emission process was studied. The fluorescence intensity was measured by (Point A), at the same position in the space. It was found that the far field fluorescence of the semicircular metal groove structure was the strongest. When the wavelength is 617 nm, the electric field distribution of several typical structures and the electric field distribution of semicircular metal grooves are obtained. The far field fluorescence intensity of the fluorescent substance at different positions of the structure was studied. The final results show that compared with the glass plate structure, the far-field fluorescence enhancement multiple of the up-converted nanoparticles located at 4.4 渭 m from the bottom of the structure is 8.25. The enhancement mechanism is complicated scattering, coherent interference and optical coupling mode in the structural sample region, which leads to fluorescence enhancement. A new type of microcavity structure is designed. The substrate is Si and Sio _ 2 with five periods and two Ag reflective plates are placed horizontally. The fluorescence emission process of the structure and the other three structures are calculated, and the luminescence intensity in the far field is compared. It is proved that the structure has fluorescence enhancement effect. By analyzing the electric field at the wavelength of 656 nm, we can know that the coupling mode between the fluorescence substance and the structure is strong.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O657.3
，
本文编号：2146580
[Abstract]:With the rapid development of micro-nano photonics, a variety of multi-functional micro-nano photonic structures have been designed and fabricated, and have been applied in medical, communication and energy fields. Enhanced luminescence intensity of fluorescent materials is an important aspect of the application of micro-nano photonic structure. Led is the core device of lighting and display devices. With the development of quantum dot preparation technology, quantum dot LED has been prepared, which is superior to the current LED in the generation of white light. Therefore, it is of practical significance to study the enhancement of quantum dot fluorescence. At the same time, in the field of life science, it is very important to improve the sensitivity of fluorescence detection, and to improve the luminescence of fluorescent substances is an important prerequisite to improve the sensitivity of detection. Due to the small size of micro / nano structure, the energy density is mainly near the surface of micro / nano structure when external electromagnetic waves interact with it. In practical medical applications, especially for the measurement of cells in vitro, fluorescent substances often need to be placed in the far-field range of the structure. Therefore, it is necessary to enhance the far field fluorescence of fluorescent substance in the far field region of the structure. Based on the above analysis, in order to improve the luminous intensity of quantum dots and apply to white LED, a periodic multilayer heterostructure is designed. The effects of period number, thickness of each layer and incident angle on reflectivity and electric field distribution of several specific wavelengths are simulated by means of strictly coupled wave analysis and finite-time-domain difference method. Several high reflectance bands are realized, corresponding to UV, UV, blue, blue and red, respectively, and the high reflectance band is adjustable. The experimental results show that the structure can enhance the fluorescence of quantum dots. The enhancement mechanism is the multiple reflection and interference effect of the structure to the incident light. In order to improve the far-field luminescence of the device, a semi-cylindrical metal micron channel is designed. The time-domain and frequency-domain variations of (Point A) at the same point in structure space in two polarization modes during fluorescence excitation are studied. By studying the time domain map, it is found that each structure is easier to excite the upconversion particle than the contrast glass structure, and the frequency domain diagram shows that when the excitation light is 980 nm (the excitation wavelength of the up-converted particle), The semicircular metal grooves have the strongest light at Point A. The fluorescence emission process was studied. The fluorescence intensity was measured by (Point A), at the same position in the space. It was found that the far field fluorescence of the semicircular metal groove structure was the strongest. When the wavelength is 617 nm, the electric field distribution of several typical structures and the electric field distribution of semicircular metal grooves are obtained. The far field fluorescence intensity of the fluorescent substance at different positions of the structure was studied. The final results show that compared with the glass plate structure, the far-field fluorescence enhancement multiple of the up-converted nanoparticles located at 4.4 渭 m from the bottom of the structure is 8.25. The enhancement mechanism is complicated scattering, coherent interference and optical coupling mode in the structural sample region, which leads to fluorescence enhancement. A new type of microcavity structure is designed. The substrate is Si and Sio _ 2 with five periods and two Ag reflective plates are placed horizontally. The fluorescence emission process of the structure and the other three structures are calculated, and the luminescence intensity in the far field is compared. It is proved that the structure has fluorescence enhancement effect. By analyzing the electric field at the wavelength of 656 nm, we can know that the coupling mode between the fluorescence substance and the structure is strong.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O657.3
，
本文编号：2146580
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