内置调制层型光纤表面等离子体波共振传感器研究

研究了一种基于内置调制层结构的光纤表面等离子体波共振(SPR)传感器。通过在金膜与纤芯的内侧增覆具有不同厚度和属性的光学透明薄膜作为内调制层,构成了性能独特的光电复合薄膜,起到调节倏逝波矢量和金膜表面等离子体振荡波矢量的双重作用,进而控制共振效应,为调节灵敏度提供依据。采用时域有限差分方法对内置调制层结构光纤SPR共振激励模型属性进行数值仿真。在此基础上,研制了用于液体折射率测量的内置调制层型光纤SPR传感探针。实验结果表明,该传感器在1.335～1.392折射率范围内,随着待测液体折射率的增大,SPR共振光谱向长波方向偏移,且灵敏度达到2263.1nm/RIU,与基于纤芯-金膜-环境介质三层结构的常规光纤SPR传感器相比提高一倍,能够更好地满足环境折射率检测的需求。     

镀银空芯光纤表面等离子体共振传感器的研究

提出了一种新型的基于镀银空芯光纤结构的表面等离子体共振(SPR)传感器。建立了光学模型对传感器内的光传播进行分析,在理论上推导出了传输光谱公式。制作了不同银膜厚度的空芯光纤SPR传感器,搭建了实验系统对内芯充入不同折射率的液体介质的传感器传输光谱进行了测量,获得了相应的SPR光谱。通过理论计算和实验测量对传感器的灵敏度特性和测量准确性进行了分析讨论。结果表明该传感器是一种灵敏度较高的、能实时检测待测高折射率液体介质的SPR传感器,它在一定范围内能够很好地弥补传统光纤表面等离子体共振传感器的不足,并且开拓了空芯光纤的一个新的应用领域。     

基于银/高纯铟复合膜的表面等离子体共振折射率传感器

为了解决单一金属膜结构的光纤表面等离子体共振（SPR）盐度传感器结构不稳定且灵敏度较低的问题,设计了一种高灵敏度的锥形三芯光纤结构的SPR盐度传感器。以银膜为激发表面等离子体共振的金属层,在其表面涂覆高纯铟以增强其稳定性。通过Kretschmann四层结构模型对传感器进行理论分析,结果表明,在光纤锥区纤芯模和包层模之间会出现强烈的模式耦合,在覆膜区会激发明显的等离子体共振。对涂覆银膜和高纯铟膜的SPR传感器进行折射率性能测试,在1.4%～3.6%的盐度变化范围内,涂覆银膜和高纯铟膜的SPR传感器灵敏度高达4989.34 nm/RIU,对应的盐度灵敏度为9.1 nm/%,比仅涂覆银膜的SPR传感器灵敏度提高了44%。     

基于金银合金薄膜的近红外表面等离子体共振传感器研究

利用淀积在玻璃衬底上的金银合金薄膜作为表面等离子体共振(SPR)芯片, 构建了Kretschmann结构的近红外波长检测型SPR传感器. 采用不同浓度的葡萄糖水溶液测试了金银合金薄膜SPR传感器的折射率灵敏度. 实验结果表明随着入射角从7.5°增大到 9.5°, SPR吸收峰的半高峰宽从292.8 nm 减小到 131.4 nm, 共振波长从 1215 nm蓝移到 767.7 nm, 折射率灵敏度从35648.3 nm/RIU 减小到 9363.6 nm/RIU.在相同的初始共振波长(λ_R)下获得的金银合金薄膜SPR折射率灵敏度高于纯金膜(纯金膜在λ_R=1215 nm下的折射率灵敏度为29793.9 nm/RIU). 利用1 μmol/L的牛血清蛋白(BSA)水溶液测试了传感器对蛋白质吸附的响应.结果表明, BSA分子吸附使得金银合金薄膜SPR吸收峰红移了12.1 nm而纯金膜SPR吸收峰仅红移了9.5 nm. 实验结果还表明, 在相同λ_R下, 金银合金薄膜SPR吸收峰的半高峰宽大于纯金膜的半高峰宽, 因此其光谱分辨率比纯金膜SPR传感器低. 关键词： 金银合金薄膜 表面等离子体共振 波长检测型 高灵敏度     

基于全相位滤波技术的光纤表面等离子体共振传感解调算法

基于生物样品检测对折射率传感的迫切需求,构建一种全光纤表面等离子体共振(surface plasmon resonance,SPR)系统,并针对其设计了基于全相位滤波技术的SPR特征波长传感解调算法.基于系统仿真,理论计算了光纤SPR传感器的折射率传感灵敏度.采用全相位滤波技术提取光纤SPR传感器透射光谱的特征波长,理论推导了全相位滤波器的解析表达式.实验结果表明,使用本算法的光纤SPR传感器折射率传感灵敏度为1640.4 nm/RIU,折射率检测的分辨率是7.36×10~(-4)RIU,与传统方法相比,有效提高了系统的检测精度和抗光源扰动性能,降低了实验成本.     

基于双峰谐振效应的镀金属长周期光纤光栅液体浓度传感器

利用长周期光纤光栅(LPFG)中的双峰谐振效应,结合表面等离子体共振(SPR)传感器的高灵敏度,提出了一种新型镀金属光纤光栅液体浓度传感器.采用双包层结构模型和耦合模理论,分析r镀金属长周期光纤光栅双峰效应的谐振特性,环境折射率的传感特性以及金属膜厚对双峰LPFG灵敏度的影响.实验上制作了具有双峰效应的镀银膜长周期光纤...     

基于表面等离子共振的光纤探针折射率传感器

基于表面等离子体共振效应,设计一种锥形光纤探针折射率传感器。通过锥形结构理论模型与SPR共振模型,利用MATLAB与FDTD Solutions软件进行理论计算与模拟仿真,分析锥形光纤锥度比、传感区长度和银膜厚度对传感器发生共振时的共振深度的影响。通过对比所镀膜层的结构与厚度,从灵敏度与品质因素角度对传感器性能进行优化。结果表明随着锥形光纤锥度比增大,共振深度出现极值;传感区长度越长,共振深度越深;银膜在50 nm处传感器性能较优,银/二氧化钛复合膜结构的传感器灵敏度与品质因素高于单层膜结构传感器。     

基于表面等离子体共振的双芯光子晶体光纤横向应力传感器EI北大核心CSCD

基于表面等离子体共振(SPR)效应,设计了一种采用双芯结构光子晶体光纤(PCF)作为光波导的横向应力传感器。通过建立SPR耦合波模型和PCF结构的形变模型,利用全矢量有限元法进行数值模拟,获得了基模共振峰的偏移量与横向应力的关系。结果表明共振峰波长的偏移量与所施加应力具有很好的线性关系。对PCF的截面结构进行优化设计,通过选择适当的空气孔层数、直径和周期,可获得较高的测量灵敏度。该研究可为基于SPR的PCF横向应力传感器的设计提供理论依据。     

螺旋形塑料光纤表面等离子体共振折射率传感器

研究了基于波长调制的螺旋形塑料光纤(plastic optical fiber, POF)表面等离子体共振(surface plasmon resonance, SPR)折射率传感器。采用机械热压和扭曲法将塑料光纤制备成螺旋形,在螺旋形POF上通过磁控溅射蒸镀一定厚度(约50 nm)的金属薄膜来激励SPR效应,从而形成螺旋形POF-SPR传感器。通过对螺旋形POF-SPR传感器的结构进行修饰,研究不同结构参数对折射率传感特性的影响。实验结果表明:由厚度为500μm扁平形POF扭制、螺纹数为4的螺旋形POF-SPR传感器具有较好的线性度和折射率传感特性,在折射率为1.335～1.400范围内测得的灵敏度为1 262 nm/RIU。该传感器具有成本较低、制备简单、结构稳定等优点。     

基于表面等离子体共振的双芯光子晶体光纤横向应力传感器

基于表面等离子体共振(SPR)效应,设计了一种采用双芯结构光子晶体光纤(PCF)作为光波导的横向应力传感器。通过建立SPR耦合波模型和PCF结构的形变模型,利用全矢量有限元法进行数值模拟,获得了基模共振峰的偏移量与横向应力的关系。结果表明共振峰波长的偏移量与所施加应力具有很好的线性关系。对PCF的截面结构进行优化设计,通过选择适当的空气孔层数、直径和周期,可获得较高的测量灵敏度。该研究可为基于SPR的PCF横向应力传感器的设计提供理论依据。     

Investigation of dual-channel fiber-optic surface plasmon resonance sensing for biological applications

A dual-channel fiber-optic sensor based on surface plasmon resonance (SPR) for self-referencing refractive-index measurements has been proposed. Most applications of fiber-optic SPR sensors are designed to measure the refractive index of a liquid or gas sample by measuring the signal from a single surface, the sensitivity and stability of which is easily affected by the fluctuation of external environmental conditions. We have designed a dual-channel fiber-optic surface sensor with two independent SPR signals from two areas of the same probe. A prototype sensor was fabricated and characterized. The preliminary experimental results demonstrate the characteristic responses of both SPR signals from two channels that independently correspond to the refractive index changes in the liquid samples with which they are in contact. The design could be extended to a multichannel sensor with further developments. The experimental results confirmed that one channel can be used as a reference sensor that could compensate for unexpected changes in bulk refraction or temperature and develop this sensor as a practicable high-sensitivity biosensing device.     

Fiber-optic surface plasmon resonant sensor with low-index anti-oxidation coating

A multimode fiber-optic surface plasmon resonance(SPR) sensor with a MgF2 film as a modulated layer is studied.The fiber-optic SPR sensor is investigated theoretically,specifically the influence of the dielectric protecting layer,using a four-layer model.The sensor is then fabricated with the optimal parameters suggested by the theoretical simulation.The sensor has a high sensitivity in the analyte refractive index(RI) range of 1.33-1.40.The best sensitivity of 4 464 nm/RIU is achieved in the experiment.The use of dielectric film(MgF2) can not only modulate the resonance wavelength of the sensor,but also protect the silver film from oxidation.     

基于辅助电介质层的棱镜表面等离子体共振效应研究

研究了一种基于棱镜基底-辅助电介质层-金膜-待测介质四层结构的表面等离子体共振(surface plasmon resonance,SPR)效应激励模型.采用薄膜光学与波导理论,探索了由辅助电介质层与金膜复合而成共振薄膜对SPR效应的激励机理与调制特性.借助时域有限差分方法,数值模拟得到辅助电介质层属性与共振能量传输特性关系.在此基础上,构建了波长调制型棱镜辅助电介质层结构SPR激励系统.研究结果表明,当待测介质折射率相同时,相较基于棱镜基底-金膜-待测介质三层结构的Kretschmann激励模型,辅助电介质层激励模型共振光谱整体向长波方向偏移且半波宽度出现显著展宽效应.而当待测介质折射率增大时,辅助电介质层型激励模型的共振光谱不仅会向长波方向偏移,而且折射率响应灵敏度比棱镜Kretschmann三层激励模型高出75%.因此该模型能够为诸如高灵敏度检测、新型光学滤波与调制器件设计等领域的研究应用提供理论与实践储备.     

Tapered fiber optic surface plasmon resonance sensor for analyses of vapor and liquid phases

We report a new approach to analyze both vapor and liquid phases by utilizing a tapered fiber optic surface plasmon resonance (SPR) probe. This technique employs a fiber optic SPR probe with a modified geometry to tune the SPR coupling wavelength-angle pair. The observed composite spectrum included two distinct SPR dips associated with surface plasmons excited in the gas and liquid active regions. This sensor is able to detect refractive index changes in both vapor and liquid phases individually by simultaneous monitoring SPR coupling wavelengths from the two sensing surfaces.     

Lossy mode resonance-based uniform core tapered fiber optic sensor for sensitivity enhancement

A lossy mode resonance (LMR)-supported fiber optic sensor in which a uniform fiber core is placed among two identical tapered regions, is investigated numerically. Indium tin oxide (ITO) and aluminum-doped zinc oxide (AZO) are considered as LMR active materials used to excite several lossy modes and gold and silver are used as surface plasmon resonance (SPR) active materials. In this probe design, a central uniform core coated with ITO/AZO is the active sensing region, whereas tapered regions are meant for bringing the incident angle close to the critical angle. The sensitivity of the present fiber optic bio-sensor is evaluated for first two LMRs utilizing both ITO and AZO separately, along with its variation with the taper ratio (TR). For ITO, the maximum sensitivity values are observed to be 18.425 μm RIU⁻¹ (refractive index unit) and 0.825 μm RIU⁻¹, corresponding to the first and second LMRs, respectively, at a TR of 1.6 and for AZO, equivalent values are 0.79 μm RIU⁻¹ and 0.35 μm RIU⁻¹, respectively, at a TR of 2.0. The results illustrate that the first LMR is more sensitive than the second LMR and the ITO-coated probe possesses greater sensitivity than the AZO-coated probe for both LMRs. Similarly, for the fiber optic SPR sensor, the maximum value of sensitivity is 5.6425 μm RIU⁻¹, in the case of gold and 5.0615 μm RIU⁻¹ in the case of silver, at a TR of 1.6. Hence, the result shows that the sensor with the present fiber optic probe design has around a 3-fold enhancement in sensitivity compared with conventional SPR sensors. This study will have applications in many sensing schemes where the requirement of large sensitivity is vital.     

Polarization detection analysis of dual-channel surface plasmon resonance sensing for silicone oils based on the D-shaped fiber with a central hole

We present and numerically characterize a dual channel surface plasmon resonance (SPR) sensor based on a D-shaped fiber with a central hole for silicone oil detections. The proposed design incorporates two metalized channels to facilitate the simultaneous detection of one group of silicone oils, which can consist of two different species. It has been demonstrated that the p-polarized input light can induce two peaks among surface plasmon resonance places, which come from the coupling between the core-guided mode and the fundamental surface plasmon polariton (SPP) modes at the D-shaped surface and around the central hole surface. However, the s-polarized input light can only induce one peak among surface plasmon resonance places, which comes from the coupling between the core-guided mode and the fundamental SPP mode around the central hole surface. The simulation results show that the characteristic responses of two channels independently correspond to the refractive index variations in the silicone oils with which they are in contact. A maximum sensitivity of 3500 nm/RIU (refractive index unit) and 4400 nm/RIU are achieved for channel A and B, respectively. This kind of sensor structure and polarization related demodulation method is promising in the simultaneous multi-analytes sensing applications in the future.     

Design of Highly Sensitive Surface Plasmon Resonance Sensors Using Planar Metallic Films Closely Coupled to Nanogratings

We investigate the sensitivity enhancement of surface plasmon resonance （SPR） sensors using planar metallic films closely coupled to nanogratings. The strong coupling between localized surface plasmon resonances （LSPRs） presenting in metallic nanostructures and surface plasmon polaritons （SPPs） propagating at the metallic film surface leads to changes of resonance reflection properties, resulting in enhanced sensitivity of SPR sensors. The effects of thickness of the metallic films, grating period and metal materials on the refractive index sensitivity of the device are investigated. The refractive index sensitivity of nanograting-based SPR sensors is predicted to be about 543 nm/RIU （refractive index unit） using optimized structure parameters. Our study on SPR sensors using planar metallic films closely coupled to nanogratings demonstrates the potential for significant improvement in refractive index sensitivity.     

波长调制型表面等离子体共振的传感特性研究

表面等离子体共振(SPR)光学传感器能实现生物医学的快速、 无标记、 高精度检测,是生物化学分析的重要方法。 研制了基于波长调制型的Kretschmann结构表面等离子体共振(SPR)生物传感系统,研究了在体溶液传感方式下的传感性能。 利用不同浓度的乙醇和乙二醇溶液进行体溶液传感测试。 实验结果表明,在折射率低时共振波长对折射率变化响应的灵敏度低,但响应的线性度高;随着折射率增大,共振波长对折射率的响应变化的灵敏度提高。 在1.407 0～1.430 RIU折射率范围内,灵敏度高达11 487 nm·RIU-1。 传感器的共振波长的稳定性为0.213 8 nm,可分辨最小折射率趋近10-6 RIU。 所研制的波长调制型表面等离子共振传感器操作简单、 灵敏度高、 检测范围大,可实现浓度极低生物标记物的有效检测,在化学、 生物传感领域有重要的应用。     

Sensitivity enhancement for a multimode fiber sensor with an axisymmetric metal grating layer

This paper proposes a novel design for a surface plasmon resonance (SPR) fiber sensor with an axisymmetric sub-wavelength metal grating layer. The relationship between the sensor performance (the sensitivity S and the quality factor Q of the SPR dip) and the characteristic parameters are investigated. Numerical simulation results show that the proposed sensor can achieve a maximum sensitivity of 13,000 nm/RIU (refractive index unit) for a refractive index range from 1.3 to 1.4.