基于新型光学芯片的荧光辐射场调控

发布时间:2019-04-26 13:07
【摘要】:荧光技术在光学成像,生命科学,化学分析等领域有着重要的应用,提高荧光的探测效率和探测灵敏度一直是人们重点研究的问题。近年来,随着微纳加工技术日趋设成熟,基于微纳复合结构的新型光学芯片越来越多的被用来实现荧光辐射场的调控。本论文主要提出了几种新型的光学芯片,通过对微纳复合结构中的模式进行分析,利用本征场与激发的荧光分子的耦合,实现对光场强度、方向、以及偏振等特性的调控;利用后焦面成像系统,对耦合辐射场的光学行为进行表征,并且基于此提出了光学参数测量新方法。利用微纳加工制作的光学芯片结构紧凑,有利于结构的小型化和一体化,在荧光显微成像,药物检测,以及传感分析等领域有重要的应用前景。本论文主要包括以下几方面的内容:1.自主搭建了后焦面成像系统。利用后焦面表征光场的辐射角度、强度、偏振等信息,系统的分析了后焦面上某一点位置所对应的辐射角。并且通过后焦面上角度的变化,可以得到相应模式的波矢变化,可用于薄膜、液体等折射率及厚度测量。2.设计了基于介质光栅实现表面波耦合辐射光场在自由空间收集的光学芯片。激发的荧光分子与表面波的耦合出射能够实现荧光的定向辐射,提高灵敏度。利用结构底部的亚波长介质光栅,实现了对辐射场的进一步调制,从而能够在自由空间收集。3.提出了小孔-Tamm复合结构,利用转移矩阵方法分析了光场在结构中的传输与共振模式,通过FDTD模拟该结构与激发的荧光分子相耦合的远场信息。证明了远场辐射方向、辐射强度可以通过改变出射波长、偶极子位置、小孔尺寸来调控。本论文的创新点主要包括:1.搭建的后焦面成像系统集光源、透镜组和滤波片组于一体,可以切换白光和激光作为光源,选择合适的波长,并且可以同时对前、后焦面成像。可以直观的表征荧光分子与光学芯片耦合后的方向与强度信息,具有很高的灵活性和实用性。2.首次提出利用介质光栅实现表面波耦合辐射场在自由空间的收集,并且刻写了二维光栅,实现了多个方向上光场的调制,和传统结构的表面波耦合辐射相比,这一新型微纳结构提高了荧光的探测效率、灵敏度和信噪比。3.小孔-Tamm复合结构将表面结构和Tamm相结合,既保持了传统Tamm结构实现荧光垂直出射的特点,同时位于小孔中的荧光分子能够更好的与Tamm等离激元耦合,从而进一步实现了荧光的增强。从FDTD模拟结果上看,与传统的Tamm结构相比,场强提高了两个数量级。
[Abstract]:Fluorescence technology has important applications in the fields of optical imaging, life science, chemical analysis and so on. To improve the efficiency and sensitivity of fluorescence detection has always been a key issue for people to study in the field of optical imaging, life science, chemical analysis and so on. In recent years, with the maturity of micro / nano processing technology, more and more novel optical chips based on micro / nano composite structure have been used to control the fluorescence radiation field. In this thesis, several new optical chips are proposed. By analyzing the modes in the micro / nano composite structure, the coupling between the intrinsic field and excited fluorescence molecules is used to control the intensity, direction and polarization of the light field. The optical behavior of the coupled radiation field is characterized by a rear focal plane imaging system and a new method for optical parameter measurement is proposed. The optical chip fabricated by micro-nano-machining is compact in structure, which is beneficial to the miniaturization and integration of the structure. It has an important application prospect in the fields of fluorescence microscopic imaging, drug detection, and sensing analysis. This paper mainly includes the following aspects: 1. The rear focal plane imaging system is built independently. The radiative angle, intensity and polarization of the light field are characterized by the post-focal plane, and the radiation angle corresponding to a point on the post-focal plane is systematically analyzed. Through the change of angle on the back focal plane, the wave vector of the corresponding mode can be obtained, which can be used to measure the refractive index and thickness of thin film, liquid, etc. 2. An optical chip based on dielectric grating for surface wave coupled radiation field collection in free space is designed. The coupled emission of excited fluorescence molecule and surface wave can realize the directional radiation of fluorescence and improve the sensitivity. The sub-wavelength dielectric grating at the bottom of the structure is used to further modulate the radiation field, so that the radiation field can be collected in free space. 3. The micropore-Tamm composite structure is proposed. The transfer matrix method is used to analyze the propagation and resonance modes of the light field in the structure. The far-field information of the coupling between the structure and excited fluorescent molecules is simulated by FDTD. It is proved that the radiation intensity can be controlled by changing the emission wavelength, the position of the dipole, and the size of the hole in the far-field radiation direction. The innovations of this paper include: 1. The post-focal plane imaging system is composed of light source, lens bank and filter bank. It can switch white light and laser as light source, select appropriate wavelength, and can simultaneously image front and back focal plane. It can directly characterize the direction and intensity information of the coupling between fluorescent molecules and optical chips, which has high flexibility and practicability. 2. A dielectric grating is proposed for the first time to realize the collection of surface wave coupling radiation field in free space, and a two-dimensional grating is written. The modulation of light field in multiple directions is realized, compared with the surface wave coupling radiation of traditional structure. This new micro / nano structure improves fluorescence detection efficiency, sensitivity and signal to noise ratio. 3. The pore-Tamm composite structure combines the surface structure with the Tamm structure, which not only preserves the characteristic of the traditional Tamm structure to realize the vertical emission of fluorescence, but also the fluorescence molecule located in the pore can be better coupled with the Tamm and other exciton. Thus, the fluorescence enhancement was further realized. From the FDTD simulation results, compared with the traditional Tamm structure, the field strength is improved by two orders of magnitude.
【学位授予单位】:中国科学技术大学
【学位级别】:硕士
【学位授予年份】:2017
【分类号】:TN491

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