单层介质膜保偏全反射直角三棱镜镀膜材料的选择及其微分相位特性…

入射角，基底玻璃折射率，膜介质折射率，膜厚等因素会影响单层介质膜保偏全反射直角三棱镜的保偏特性，且各因素的影响程度并不相同。本文分析上述各因素的微小变化对保偏特性的影响，并提出了选择膜介质的方法。     

单层介质膜反射棱镜式光学相位延迟器件研究

反射式介质膜光学相位延迟器件在具有波片的功能的同时,还可用作光束保偏(或相移)转向器件及光束保偏(或相移)平移器件等,是光学领域中近10多年出现的新型器件,在科研与光学工程中有广泛的应用与需求.本文从理论上系统地研究了各相关因素对单层介质膜反射棱镜式光学相位延迟器件相位特性的影响,探讨了该类光学相位延迟器件的设计方法,给出了一个设计实例及相应的实验结果.     

线性共蒸法制备非均匀膜的误差特性模拟分析

对双源线性共蒸法制备的非均匀薄膜折射率分布与光学特性的关系作了探讨,并与均匀介质膜的光学特性作了对比;从折射率正变和负变两个方面,讨论了混合介质膜折射率不同变化规律对光学性能带来的影响;讨论了厚度误差和折射率极值误差对非均匀膜光学性能的影响。结果发现折射率变化规律误差主要对非均匀膜的应用波段范围产生影响,而膜层厚度误差和折射率极值误差超过一定值时,将对薄膜光学特性产生重要影响。     

高折射率椭圆芯布拉格光纤的偏振特性

应用带完全匹配层边界条件的全矢量有限元方法,分析了高折射率椭圆芯布拉格光纤的偏振特性,详细讨论了光纤结构参量对模式双折射度以及群速度走离的影响,结果发现:高折射率椭圆芯布拉格光纤的模式双折射度可达10-2量级,比传统保偏光纤至少高出一个量级,并且表现出不同于传统保偏光纤的群速度走离特性;在保持较高双折射度的同时,通过合理的结构设计,可在一定的波长处灵活地获得较大的群速度走离或零走离特性,具有重要的潜在应用价值;最后,简要分析了低折射率区域的折射率变化对偏振特性的影响;研究结果有助于设计高性能的微结构保偏光纤。     

熊猫型保偏光纤定轴仿真研究

应用光波导理论分析了保偏光纤的POL定轴方法的基本原理.根据熊猫型保偏光纤的折射率分布模型,采用光束传播方法对影响熊猫型保偏光纤POL曲线分布的各种因素进行了仿真研究,包括不同观测平面、不同折射率分布(匹配型或非匹配)、是否加匹配液等因素.通过仿真结果与实验观测结果以及保偏光纤与单模光纤仿真结果比较,表明了理论分析与仿真方法的可行性.     

模间干涉的包层腐蚀型椭芯保偏光纤折射率传感特性

研究了一种基于模间干涉原理的微型椭芯保偏光纤的折射率传感特性。利用氢氟酸腐蚀的方法将椭芯保偏光纤制作成折射率灵敏的传感头,传感头可以根据控制腐蚀时间灵活控制其锥区结构。详细分析了保偏光纤内基模与一阶高次模模间干涉产生的双边瓣能量分布与被测折射率的关系,深入研究了锥区半径、工作波长对折射率灵敏度的影响。研究结果表明,光源波长为980 nm,折射率在1.39附近时,半径为8μm的传感头折射率灵敏度能够达到-7.1/RIU(即归一化光强与RIU之比,其中RIU为单位折射率)。     

熔锥型熊猫光纤耦合器的传输特性分析

熔锥型保偏耦合器的传输特性决定了其光学原理与功能的实现。为了从理论上分析各参量对保偏耦合器传输特性的影响,基于热-结构-电磁多物理场耦合理论,建立了熔锥型熊猫光纤耦合器双锥模型,应用有限元法,分析了各参量对熊猫光纤耦合器传输特性的影响。结果表明应力区与包层折射率差影响耦合区纵向电磁场的分布,折射率差越大,纵向电磁场分布的变形也越大;HE1x1模和HEy11模的传播常量对偏振主轴角度差不敏感,偏振主轴角度差是通过耦合系数进而影响保偏光纤耦合器的消光比的;HE1x1模的传播常量对熔锥的熔锥区横截面椭圆率比较敏感,横截面椭圆率变化6.67%时Δβx11变化0.14%,计算结果表明当熔锥区横截面椭圆率为0.56时可获得较高性能的耦合器。     

基于平面波导激励的修正长程表面波的传感器研究

为了解决传统的强度检测型波导激励的表面等离子体共振传感器灵敏度不高的缺点,研究平面波导激励的介质膜-金属-被测介质的可激发修正的长程表面等离子体波结构。采用离子交换的方法制备折射率可用费米函数拟合的平面波导,研究了离子交换时间对平面波导的模数及等效折射率等特性的影响,为激励波导的优化设计提供有效依据。采用制备的平面波导激励介质膜-金属-被测介质的非对称结构,研究金属材质、介质膜厚和金属膜厚等因素对修正的长程表面等离子体波特性的影响,对被测溶液的折射率进行检测。实验结果表明,其灵敏度为传统的强度检测型表面等离子体共振传感器的6倍,并且具有较好的线性关系。     

保偏微纳光纤倏逝场传感器

近年来,保偏微纳光纤以其高双折射特性和强倏逝场效应引起了研究者的关注.本文从保偏微纳光纤的结构类型、制备方法和模式双折射特性等出发,介绍了目前不同类型保偏微纳光纤倏逝场传感器的构造特征与实现方法,利用保偏微纳光纤在两个垂直偏振方向的倏逝场对外界的不同响应,可制成偏振相关的干涉型或光栅型等传感器件.本文探究了包括超高折射率灵敏度特性和温度不敏感特性等的内在产生机理,并考察了保偏微纳光纤倏逝场传感器在折射率、湿度、磁场和特异性DNA分子探测等方面的应用,其结果对微纳光纤及其传感器的研究和应用具有重要的意义.     

涂有半导体气敏薄膜的长周期光纤光栅气敏传感特性理论分析

首先利用耦合模理论研究了长周期光纤光栅LPFG折射率敏感特性,数值计算了长周期光纤光栅透射谱谐振波长与环境介质折射率的关系。其次分析了半导体氧化物气敏膜光学特性机理,当气体与薄膜接触时,气体会使敏感膜的消光系数、吸收系数和相应的折射率发生变化。基于上述两点,提出可将气敏膜涂于光栅表面,利用气敏膜的折射率随环境气体成分和浓度变化而变化的特性,从而影响LPFG透射谱谐振波长的变化,通过检测波长的变化达到探测气体成分和浓度的目的。由于长周期光纤光栅对环境介质折射率的灵敏度高于光纤,且其传感信号属于波长调制,测量信号不受光强波动及光纤损耗的影响,因此其灵敏度比强度型光纤气体传感器高。     

Design of a wedge plate for polarization-preserving angular shifter

It is shown that by using a wedge plate, the incident direction of light propagation can be rotated as necessary while still preserving beam polarization. The basic conditions of these preservations of polarization are deduced. For numerical demonstration, it is shown that a collimated beam with +45° linear polarization can be guided to any pre-settled direction where the square of ellipse ratio variation in the polarization is less than 0.0001%, while the variation of squared ellipse ratio of a right circular polarization beam is kept under 0.1%.     

Polarization reversal behavior of an asymmetric ferroelectric thin film

Using the Landau–Khalatnikov equation of motion, the polarization reversal behavior in an asymmetric ferroelectric thin film has been studied. Our model first introduces a third power of polarization to describe the asymmetry of a ferroelectric thin film with surface transition layer, which originates from the difference between the surfaces. Interestingly, vertical drift of polarization switching behaviors was found in this system. The properties consisting of hysteresis loop, spontaneous polarization, switching current of an asymmetric ferroelectric thin film with surface transition layer are discussed.     

水面油膜偏振反射影响因子及其交互作用定量分析

为了利用遥感技术提取更多水面油膜的反射特征信息,在传统遥感研究的基础上,对水面油膜的多角度高光谱偏振反射信息进行了测量与分析,且以偏振度作为定量研究指标,采用3因素3水平的正交实验研究了入射天顶角、波段和油膜厚度以及它们之间交互作用对水面油膜偏振度的影响.对正交实验数据进行方差分析结果表明3个因素与它们之间的交互作用对水面油膜的偏振度均有影响;而入射天顶角、油膜厚度以及波段与油膜厚度的交互作用对偏振度的影响高度显著,说明在利用多角度高光谱偏振反射信息研究水面油膜时,不但要考虑单一因素对偏振度的影响,而且必须要考虑因素间交互作用对偏振度的影响.     

Effective dielectric constant model of electromagnetic backscattering from stratified air–sea surface film–sea water medium

Studies of surface film medium on the sea surface are carried out in this paper for developing the technology to automatically detect and classify sea surface films, and an effective dielectric constant model of electromagnetic backscattering from a stratified air–ocean interface. Numerical results of the new model show the characteristics of effective dielectric constants for the air–sea surface film–sea water medium as follows. The effective dielectric constants decrease with increasing relative dielectric constants of the sea surface films. The effective dielectric constants decrease in horizontal polarization(abbr. HH polarization) and increase in VV vertical polarization(abbr. VV polarization) with increasing radar incident angle. Effective dielectric constants vary with relative sea surface film thickness as a cosinusoidal function of sea surface film thickness. Effective dielectric constant of VV polarization is larger than that of HH polarization. Two potential applications are found with our model, i.e., the retrieval of dielectric constants from the sea surface film, and the film thickness retrieval with our model. Our model has a highly significant influence on improving the technology related to the remote sensing of sea surface films.     

Modeling and computer design of liquid crystal display backlight with light polarization film

The article is devoted to elaboration of the model of scattering polarization film like dual brightness enhancement film (DBEF). This model is used for computer design of backlighting system of liquid crystal display (LCD) where light polarization is important. The model elaboration required development of measurement methods and reconstruction of the parameters for the film polarization, development of the accurate computer model of the polarized light scattering on thin surface. The results of design of LCD backlight with polarization film are presented in the article as well. So it was demonstrated that design of backlight devices with DBEF is possible with help of elaborated software.     

Four-space formulation of Dirac's equation

Dirac's equation is reformulated in a way which, while preserving the usual energy levels, leads to predictions of vacuum polarization that may be experimentally testable.     

基于遗传算法的斜入射窄带滤光片膜系优化设计

根据薄膜窄带滤光片在斜入射时的偏振特性,提出了基于遗传算法的斜入射薄膜窄带滤光片膜系优化设计方法.根据开发的程序,设计并制备了一组可用于18°倾斜入射的0.8纳米信道间隔的五腔薄膜窄带滤光片.该滤光片能有效地抑制斜入射时偏振光中心波长的分离现象,降低器件的偏振相关损耗,通过角度调谐能实现选择波长的改变.通过与针法设计的滤光片膜系相比,遗传算法得到的膜系具有更高的矩形度、更大的波长调谐范围以及更低的偏振相关损耗.实验结果表明其满足设计要求并有超过25纳米的波长调谐范围.     

High-energy handling capabilities of optical fibers: Application to pulse compression and direct generation of megawatt picosecond pulses

The compression of the output of a Q-switched, mode-locked Nd:YAG (130 ps, 1.06 m) is reported for a number of different core-size single mode, multimode and polarization preserving fibers at power levels near the damage threshold. In maximizing the energy throughput, the main limitations are dielectric breakdown and nonlinear induced birefringence. Compressed pulse stability is found to depend critically on core size at this power level. An optimized compressor has been obtained capable of compression factors up to 35 (3.7 ps) with peak power in excess of 2 MW. Second-harmonic generation has been observed in polarization preserving fibers.     

温度变化对金属Ag膜反射镜偏振特性的影响研究

空间遥感应用中的光学有效载荷对系统偏振控制提出了越来越高的要求,作为常用的宽光谱反射镜,金属银(Ag)膜反射镜的偏振特性随着环境温度的改变而变化。本文设计并制备了低偏振灵敏度的Ag膜反射镜,研究了反射镜在45°和60°入射角下,从室温25℃升温到150℃时的偏振特性变化和反射光谱变化情况。随着温度的升高,Ag膜的折射率在350~1 200 nm波长范围内有所增加;Ag膜反射镜的反射光中s和p光的相位差Δ在350~600 nm波长范围内减小,在600~650 nm波长范围内基本稳定,在650~1 200 nm波长范围内增大。温度上升到125℃时,Ag膜和反射镜表面形貌发生改变,增加了表面散射和吸收,导致350~900 nm波段反射率降低,在波长350 nm附近的降低约25%。     

Modulation of the polarization state of light using a weak anisotropic thin film

The polarization state of light is modulated by an anisotropic thin film. An anisotropic MgF(2) film is deposited onto a plate that is put in contact with a BK7 prism to form a BK7 prism/film/air configuration. It is shown that the polarization state of reflected light can be easily modulated from a linear state to a circular state by rotating the thin-film plate.