【作者】 谢志国；

【导师】 明海； 鲁拥华；

【作者基本信息】 中国科学技术大学 ， 光学， 2009， 博士

【摘要】 纳米传感技术近年来发展成为国内外研究的热点之一。本论文基于金属纳米颗粒结构的光学特性,结合光纤传感技术,对金属纳米颗粒的光纤传感特性进行了研究。理论上,采用离散偶极子近似研究了金属纳米颗粒的局域表面等离子体共振和局域电场增强特性。实验中,通过化学合成法制备金属纳米球和纳米棒。利用不同结构光纤如:去包层的多模石英光纤、石英光纤锥形探针、聚合物光纤锥形探针,光子晶体光纤,分别研制了光纤局域表面等离子体共振消光传感器,石英光纤锥形表面增强拉曼散射（SERS）探针,聚合物光纤锥形SERS探针以及宽谱的实芯光子晶体光纤SERS传感器。本论文主要研究工作和成果如下:1.理论上,利用离散偶极子近似算法研究了金属纳米球形的局域表面等离子体特性。分析了基底与金属纳米颗粒,颗粒与颗粒之间的相互耦合作用对局域表面等离子体共振消光传感特性影响。实验中,采用化学自组装技术制备了光纤局域表面等离子体共振消光传感器,测量其对周围介质环境的折射率传感特性,获得99±4nm/RIU灵敏度。实验现象与理论基本一致,光纤基底和颗粒团簇对局域表面等离子体共振峰和传感灵敏度有重要的影响。2.采用拉锥和化学自组装法制备了石英光纤SERS锥形探针,实现了对10^-6M浓度的4MBA分子SERS信号的探测。为了改善光纤锥形SERS探针的柔韧性,提高其实用性。提出了基于金纳米棒的聚合物光纤SERS锥形探针。理论上研究了金纳米棒的横向、纵向局域表面等离子体的局域场增强特性。实验中制备了聚合物光纤SERS锥形探针,采用TERS结构代替传统的光纤SERS结构,有效的避免了聚合物光纤自身强的拉曼散射背景,获得了10⁹量级的R6G分子的拉曼增强。3.研制了基于实芯光子晶体光纤的宽谱SERS传感器。理论上提出,除了倏逝场机制外,在该光纤SERS结构中泄漏模机制在SERS的激励和信号的收集中起到重要的作用。实验中通过可见光514.5nm和近红外光785nm的激励,演示了对10^-6M的4MBA分子SERS信号的测量,验证宽谱的特性。结果分析表明,宽谱SERS特性依赖于银纳米颗粒团簇体的表面等离子体共振强度,实芯光子晶体光纤的SERS激励和收集效率以及分子自身的拉曼散射截面。本文创新点主要包括:1.提出并制备了基于金纳米棒的聚合物光纤SERS锥形探针,利用TERS结构克服了聚合物光纤自身强的拉曼散射背景的影响,在实验中获得了10⁹量级的R6G分子的拉曼增强,该结果对发展制作一次性光纤SERS探针有重要的意义。2.研制了宽谱的光子晶体光纤SERS传感器。理论上提出了泄漏模机制在SERS的激励和信号的收集中发挥着重要作用。实验上开展了可见光514.5nm和近红外光785nm的SERS传感实验,验证了宽谱的SERS特性。实验结果表明,银纳米颗粒团簇体的表面等离子体共振强度,实芯光子晶体光纤的SERS激励和收集效率,分子自身的拉曼散射截面对宽谱的实芯光子光纤SERS特性有重要的影响。更多还原

【Abstract】 The nanometer sensing technology has become one of hot researches in near years.This article makes a study on optical fiber sensor with metal nanostructure based on the properties of optical fiber sensing technology and the optical performances of metal nanoparticles.Theoretically,localized surface plasmons resonant（LSPR） and electric filed enhancement are simulated by Discrete Dipole Approximation method.In experiment,metal nanoshperes and metal nanorods are synthesized.With the different fiber structure,such as multimode silica fiber,silica fiber taper,polymer optical fiber（POF） taper,and solid core photonic crystal fiber optical fiber localized LSPR sensor,silica fiber surface enhanced Raman scattering （SERS） taper probe,POF SERS taper probe,and broad spectral PCF SERS sensor,are developed respectively.The main research works and conclusions are as following:1.Localized surface plasmons（LSPs） on metal nanospheres are simulated by the discrete dipole approximation（DDA） method.In the optical fiber LSPR sensor, substrate-nanaoparticle interaction and nanoparticle-nanoparticle interaction are considered.With chemical self assembly method,an optical fiber LSPR sensor is developed.The sensing sensitivity reaches 99+4nm/RIU by measuring the response of refractive index on environment dielectric.The experiment result indicates that the sensitivity of this sensor is influenced by fiber substrate and nanoparticles aggregation.2.The silica fiber SERS taper probe is prepared with fused taper method and self assembly way.The 4-MBA molecule with 10^-6M concentration is measured with this sensor.The 4-MBA molecule SERS spectrum is achieved successfully.To improve the flexibility of fiber SERS probe for application,a novelty polymer optical fiber SERS probe is presented based on gold nanorods.The transverse and longitudinal LSPs of gold nanorods are researched on electrnic field enhanment. To substitute the traditional fiber SERS configuration with TERS configuration, the background of POF self Raman scattering is avoided effectively,and an enhancement factor with 10⁹ is obtained in the R6G molecule SERS experiment. 3.The broad spectral solid core photonic crystal fiber SERS sensor is developed.In theory,except for evanescent wave mechanism,the leakage mode mechanism is presented in SERS exciting and collecting process in this sensor structure.In experiment,with the excitation of visible light 514.5nm and near infrared light 785nm respectively,the SERS spectrum of the 4-MBA molecule with 10^-6M is demonstrated,thus the broad spectral SERS property is validated.The result shows that the performance of this broad spectral PCF SERS sensor is dependent on the LSPR intensity of silver nanoparticles cluster,the SERS exciting and collecting efficiency of solid core PCF,and the self Raman scattering cross section of analyte molecule.Highlights of the dissertation are as following:1.A novelty polymer optical fiber SERS probe based on gold nanorods is presented. To substitute the traditional fiber SERS configuration with TERS configuration, the background of POF self Raman scattering is avoided effectively,and An SERS enhancement factor with 10⁹ is obtained.2.A new broad spectral solid core photonic crystal fiber SERS sensor is developed. In theory,the leakage mode mechanism is presented in SERS exciting and collecting process.The broad spectral SERS property is validated by the demonstration of SERS experiment in visible light 514.5nm and near infrared light 785nm.The important factors in the influence of the performance of this broad spectral PCF SERS sensor are analyzed.更多还原