具有内参考热补偿功能的三层膜结构微球腔折射率传感器

tBtB光学微腔在高灵敏度传感中有着重要的应用前景,而在传感中热漂移是制约其走向实用的重要因素.本文提出了一种镀有三层膜结构的微球腔,可以在实现高灵敏度折射率传感的同时,具备内参考热补偿功能.该结构由内到外分别涂覆折射率为高、低、高的薄膜,内外两高折射率层可以分别支持各自的回音壁模式,称之为内层模式和外层模式.研究了波导耦合的内外模式在折射率传感和温度传感应用的表现.结果表明,中间膜层厚度为550 nm时,内外模式的折射率灵敏度分别为0.0168和102.56 nm/RIU,温度灵敏度分别为–19.57和–28.98 pm/K.通过监测内外模式谐振波长的差值进行传感,对中间膜层厚度进行优化,=400 nm时,折射率灵敏度为75.219 nm/RIU,探测极限可以达到2.2×10~(–4) RIU,热漂移被减小到3.17 pm/K,极大地减小了热漂移对系统的影响.本研究可为微球腔折射率传感器的设计和改进提供指导.     

TiO2纳米粒子增强的光纤损失模式共振折射率传感器

以多模光纤为基底来实现损失模式共振(LMR)折射率传感的灵敏度较低，在利用铟锡氧化物(ITO;In₂O₃和SnO₂的质量分数分别为90%和10%)激发光纤LMR传感的基础上，在ITO薄膜上静电组装二氧化钛(TiO₂)纳米粒子，实现折射率灵敏度的提升。使用Kretschman结构模型对传感器进行理论分析，仿真分析了LMR共振阶数与ITO薄膜厚度的关系，以及ITO作为LMR膜层实现折射率传感的可行性。通过在光纤侧壁磁控溅射ITO薄膜以产生LMR效应，制备ITO-LMR折射率传感器。通过折射率传感实验对ITO-LMR和TiO₂-ITO-LMR两种传感器进行性能测试，在1.3333～1.3840的折射率变化范围内，TiO₂-ITO-LMR传感器灵敏度可达1651.659 nm/RIU，相较于ITO-LMR折射率传感器，其灵敏度提升了3.058倍。     

光波导氨敏传感器的研究

提出了一种新型的光波导氨敏传感器,将光波导中消逝波理论与纳米多孔薄膜技术相结合,在玻璃薄膜光波导上制备一层纳米TiO2多孔薄膜,并将氨敏试剂（BTB）固定在纳米TiO2多孔薄膜中,利用导波光的消逝场实时地探测敏感薄膜对导波光的吸收,实现了对氨气的探测,检测下限达到1ppm。同时对比了致密敏感薄膜和多孔敏感薄膜对氨气的响...     

矩形折射率调制型薄膜长周期光纤光栅特性研究

镀膜长周期光纤光栅传感器是目前光纤光栅传感研究的一个热点,但关于此类传感器模型的全面的理论分析目前还很少。本文基于严格的四层模型,从理论上对芯层折射率调制为矩形波调制的薄膜长周期光纤光栅的特性进行了详细的分析。在充分考虑材料色散对光纤芯层和包层的影响后,对薄膜参数、占空比和环境折射率的变化对镀膜长周期光纤光栅的谱特性的影响进行了数值研究。研究结果表明,薄膜参数对透射谱有重要影响,合理设计薄膜厚度可以获得较佳的损耗峰。研究还发现,镀膜后占空比对透射谱的影响减小,而对环境折射率变化的敏感度增加。在占空比为0.5时光栅具有最大的损耗峰值。     

聚合物波导型表面等离子体共振传感器的特性研究

基于表面等离子体共振理论,将SU-8作为波导芯层材料,以聚甲基丙烯酸甲酯(PMMA)为下包层材料,设计了一款聚合物波导型SPR传感器。理论计算了波导芯层折射率、被测物折射率、不同金属薄膜及其厚度等因素对表面等离子体共振曲线的影响。分析结果表明,在可测试范围内,被测物折射率越大,灵敏度越高;波导芯层折射率减小,共振峰向长波方向移动,被测物检测范围整体向折射率小的方向偏移,波导芯层折射率增大则相反。     

基于表面等离子体共振和定向耦合的D形光子晶体光纤折射率和温度传感器

利用光子晶体光纤结构的灵活性和性能的优越性, 设计了一种基于D形光子晶体光纤的折射率和温度传感器. 在D形光子晶体光纤表面抛磨并镀上金纳米薄膜, 作为表面等离子体共振传感通道用来测量液体折射率; 在包层的一个空气孔中填充温敏液体甲苯, 作为定向耦合通道实现对温度的测量. 进一步的数值计算发现, 基于定向耦合效应的温度传感和基于表面等离子体共振的折射率传感相互独立, D形光子晶体光纤同时进行折射率和温度传感检测. 在各向异性的完美匹配层边界条件下利用全矢量有限元法对该传感器特性进行了数值研究, 发现D形光子晶体光纤的空气孔直径决定了定向耦合吸收峰的中心波长和温度传感的灵敏度, 金薄膜的厚度和D形结构的抛磨深度仅影响表面等离子体共振峰的相对强度. 结果表明: 该传感器在-10–80 ℃的温度范围内具有11.6 nm/℃的温度灵敏度, 在1.34–1.44折射率范围内折射率灵敏度最高可达26000 nm/RIU.     

光波导振荡场传感器

针对消逝场传感器的不足,提出了一种传感介质处于波导芯层,且以超高阶导模为探针的光波导振荡场传感器.由于其波导芯层处于功率密度极高的振荡场区域,而超高阶导模又具有对芯层参数极为灵敏的性质,因此这种新型传感器的灵敏度大大增强.实现了超越消逝场传感器灵敏度极限值几个量级的位移传感器.     

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。     

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。     

基于光子晶体波导结构的甲烷与温度双参量传感器设计

通过在完整三角晶格空气孔型光子晶体平板中引入两条空气槽型波导,并在槽型波导中引入折射率随甲烷气体浓度变化的敏感薄膜,设计并优化了一种甲烷与温度双参量传感器。建立光子晶体波导传感分析模型,利用平面波展开法、等效折射率方法、时域有限差分法对甲烷和温度的传感特性进行了理论分析。结果表明,两条传感通道的通带峰值中心波长会随甲烷气体浓度增加发生线性蓝移,而随温度增加出现线性红移。其中,通道1的甲烷传感灵敏度能达到0.012 nm,温度传感灵敏度达到1.69 nm/℃,通道2的甲烷传感灵敏度能达到0.010 8 nm,温度传感灵敏度达到1.66 nm/℃,同时结合双参数矩阵法正好能解决传感交叉敏感问题。     

Multielement integrated optical devices based on high-refractive-index materials

The effect of an additional high-refractive-index layer on the properties of planar waveguides for multielement integrated optical devices is considered. The conditions for highly efficient coupling (self-coupling) upon beam propagation from the three-layer to the four-layer region are determined. Technological recommendations for the production of optical waveguide beam splitters with an increased number of output elements are given.     

Four layer polymeric mode polarization filter for integrated optics

We report on our systematic study of fabrication and characterization of four-layer polymer waveguides. Various optical properties (such as refractive index, birefringence, and propagation loss) of polycarbonate and polystyrene waveguides are presented. The thin film structure consisting of glass/polycarbonate/polystyrene/air has been used for demonstrating polarization filter action because the two polymers are quite different with respect to their optical anisotropy. Modal electric field plots for both TE and TM are generated to support the observed behavior. It is also observed that the four-layer lightguide exhibits relatively low loss values compared to the monolayer configuration.     

A new approach to determining the waveguide mode index distribution

A new approach is presented to determining the profile characteristics of planar optical waveguides. The mode index value is developed into the Lagrange series in terms of mode number, which allows one to find analytical expressions for the coefficients of that series. This method is applied to evaluating the coefficients of mode index distribution for the step-index and four-layer step-index profiles.     

包含左手材料的四层平板波导中的光导模

研究一个芯子层是左手材料,其他三层由传统材料构成的四层平板光波导系统,利用图解法对各种TE偏振的导波模式的解进行详细分析.研究表明,四层左手材料光波导既能支持振荡导模,也能支持表面导模,与三层左手材料光波导相比较,此四层波导的导波模式呈现一些新的特性.对于中间传统材料层存在振荡场的情形:芯子层支持振荡导模的光波导中存在基模,并且高阶振荡导模出现模式缺失的性质;芯子层支持表面导模的光波导可以支持基模和多个高阶模式,并且存在模式兼并的性质.对于中间传统材料层存在衰减场的情形,此四层波导结构可等效为三层左手材料光波导.这些新的光波导传输性质对各种光波导器件的制作有潜在的应用价值.     

Control of birefringence using polymer as cladding layer in optical planar waveguides

We demonstrate theoretically that a polymer layer, when used as cladding layer for silica-based planar optical waveguides on a silicon substrate, can substantially reduce birefringence. Multilayer planar optical waveguides usually exhibit stresses that are caused by thermal-induced strains that originate from the bonding of the layers, in addition to intrinsic strains. Effect of various intrinsic properties on thermal stress as a function of thickness of the guiding layer is studied. It is shown that it is possible to achieve the thermal stress free and, hence, the stress-induced birefringence free waveguide devices by proper waveguide designs.     

Fabrication and study of a metal-clad planar waveguide based biosensor

A metal-clad planar optical waveguide biosensor having five layer structure has been fabricated to study the detection of Pseudomonas and Pseudomonas-like bacteria. This waveguide is designed to increase the overlap of the evanescent field extension from the sensor face with the micro-scale biological objects in the bulk solution, to place most of the entire volume of the bacteria within the evanescent field. The results presented here leads to a significant optimization of the important design parameters to sense micro-scale biological objects. We have compared our computed results with the results obtained by similar non-metallic clad biosensor. The effect of affinity-layer refractive index on the sensitivity of these planar waveguides is also studied. We have shown this for some special cases by obtaining reflection dips at the particular angle of incidence. Our observations show that the metal-clad planar optical waveguide biosensor having higher affinity refractive index will give better sensitivity than other similar non-metallic clad biosensor. The validation of metal-clad planar optical waveguide sensor for the detection of Pseudomonas aeruginosa bacterium is also made.     

Consistency and variations in optical characteristics of four-layer polymeric waveguides

In the present work, four-layer polymeric waveguides have been fabricated and characterized by interchanging the film layer. Using polyvinyl alcohol (PVA) and styrene acrylonitrile (SAN) polymer it has been shown that polymers do not loose their own property in multilayer structure and better efficiency can be achieved in the form of low propagation losses and mode filtration. Due to high contrast of PVA and SAN films, a broad spectrum of refractive index in four-layer structure has been achieved.     

扩散平面光波导的传递函数方法

引入一种计算光波导传播特性的新方法传递函数方法。给出了公式推导,计算了扩散各向同性及扩散各向异性平面光波导的传播特性,并与其它方法所得结果进行了比较。结果表明用传递函数方法处理折射率渐变分布的光波导问题,计算相对简单,可以得到精确的数值结果。     

Stress reduction in planar waveguide using polymer top layer

Planar optical waveguides consisting of layers from different materials created at elevated temperatures usually exhibit substantial stresses. By controlling the layer thickness of polymeric top layer on planar waveguide structures, it is possible to use very thin layers for stress compensation, significantly reducing required deposition times. It is possible to reduce birefringence within planar device by controlling top polymer layer thickness with thermal expansion coefficient greater than silica or PMMA.     

Long-Period Gratings in Planar Optical Waveguides

Our progress in the study of long-period gratings (LPGs) in planar optical waveguides is reviewed. In particular,experimental LPGs in glass and polymer waveguides are presented to demonstrate the potential of LPG-based waveguide devices.