矩形波宽带通滤光膜研究

对矩形波宽带通滤光片进行了深入研究,提出了一种设计、制备矩形波宽带通滤光片的方法。使用该方法设计并制备了400 nm～1 100 nm波段,中心波长λ₀=515 nm,透射带λ=λ₀±25 nm,透射带平均透射率■≥92%,截止带λ=400 nm～475 nm、λ=555 nm～1 100 nm,截止带透射率小于0.1%的矩形波宽带通OD3-A滤光片。对样片光谱进行了测试,结果满足需求。该方法设计、制备矩形波宽带通滤光片克服了F-P型窄带滤光膜监控精度要求高、通带宽带窄、成本高以及传统长、短波截止膜组合方式膜层总厚度过大、通带透过率低、波形矩形度差的缺点。     

1555nm宽带通滤光膜的设计和优化

针对对空间通信的特殊需求,设计并制备了1 555 nm波段的高透过率、宽带通滤光膜,该滤光膜在高温高湿环境下能够稳定工作。根据薄膜设计理论,选取折射率差大的TiO2和SiO2作为镀膜材料,采用规整膜系进行膜系设计。借助Optilayer软件,采用针形优化和双面镀膜方法,得到优化的非规整膜系。采用直接与间接监控相结合的手段监控薄膜生长,并探讨了薄膜的生长条件。在电子束蒸发离子辅助沉积条件下,制备出中心波长处透过率达到97%,带宽为50 nm的滤光膜。在100℃高温和-30℃低温各保持3 h的条件下,波长漂移仅0.2 nm,具有高的稳定性和可靠性,满足空间通信的使用要求。     

粮食筛选系统中双通道带通滤光膜的研制

利用杂质和劣质粮食与优质粮食的近红外吸收光谱不同的特性,根据光谱中反映测试成分的特征波段的差异对粮食进行光学分选.在光谱进入传感器之前经过滤光片对多个测试波段进行过滤,降低噪音的影响.本文针对光学筛选系统中核心部件双通道带通滤光片进行研制,从膜系设计理论出发,采用了Smith法结合膜系设计软件设计了以周期膜系和非周期膜系相结合的双通道带通滤光膜系,利用电子束蒸发和离子辅助沉积的方法进行制备并通过数学建模分析,减小了实验误差对光谱的影响.在1 200nm和1 450nm波段得到平均透射率大于97%,1 000~1 130nm和1 570~2 000nm波段平均透射率小于1%的滤光膜,通过系统测试,满足使用要求.     

人工局域表面等离激元诱导的超透射

利用有限元方法研究了理想导体薄膜中齿状孔阵列在微波频段的超透射现象.齿状结构的引入使得孔阵列的透射谱发生红移,在更深的亚波长区实现全透射.近场分析表明分布在齿状孔上的局域态对红移起了关键作用.研究发现单个齿孔支持人工局域表面等离激元多极子模式,与超透射相关的是偶极子模式.该研究方案可以推广到红外与太赫兹频段.     

二维亚波长金属小孔阵列的透射光增强效应

对金属薄膜上的二维亚波长小孔阵列的光透射增强现象进行了数值模拟，结果显示不仅实际金属薄膜上的小孔阵列结构具有透射增强效应，理想导体薄膜的相同结构也具有透射增强效应，但没有实际金属薄膜的增强明显-通过分析指出，这种小孔阵列的光透射增强效应是一种复杂的波导耦合效应-与金属薄膜上的表面电流一样，表面等离激元波具有将入射光能量从金属表面向小孔转移的作用，但不是透射增强的本质原因- 关键词： 表面电流 共振耦合 透射增强 表面等离激元     

内嵌矩形腔楔形金属狭缝的增强透射

金属薄膜上亚波长金属狭缝的非共振光增强透射对宽频带光子器件的设计具有重要意义. 为增强金属狭缝的光透射, 设计了内嵌矩形腔楔形金属狭缝阵列, 并用有限元方法研究了该结构的透射特性. 结果表明, 内嵌矩形腔的楔形金属狭缝阵列比无矩形腔的楔形金属狭缝阵列透射率高. 此外, 还研究了矩形腔的结构参数和位置对内嵌矩形腔楔形金属狭缝阵列透射特性的影响. 这些结果将对设计具有更高透射能力的金属狭缝具有一定的指导意义. 关键词： 光异常透射 金属狭缝 表面等离极化激元     

基于等离激元法布里-珀罗腔折射率测量的实验设计

利用自下而上的纳米加工工艺,制备了一种由银纳米线对和金膜构成的等离激元法布里珀罗(F-P)腔。暗场散射光谱和数值模拟表明,金膜表面传输的表面等离激元经银纳米线对的多次反射下,会在腔内形成驻波现象,并在散射光谱中呈现出多光束干涉调制的光谱线型。利用这一原理设计一个折射率测量实验,通过测量不同浓度甘油溶液的折射率,得到了F-P腔共振波长随溶液折射率增大的线性红移规律。进而通过调谐F-P腔的长度,得到该F-P腔最高的探测灵敏度为555 nm/RIU。     

人工表面等离激元超材料

以微带为代表的传统微波传输线无法精细操控电磁模式,因此传统电子信息系统在空间耦合、动态响应和性能鲁棒性等方面存在瓶颈.人工表面等离激元(SSPP)超材料可打破上述瓶颈,是光学与信息领域的研究热点之一.人工表面等离激元超材料是一类模拟光频段表面等离激元特性的新型超材料,可在微波和太赫兹频段精细操控表面波,具有与平面电路相...     

基于一种易于制作的混合型表面等离激元波导结构的超紧凑截线滤波器

提出并分析了一种结构紧凑的截线型滤波器。该滤波器建立在一种硅基混合型表面等离激元波导结构上。与通常的混合等离激元结构相比,该波导结构在制作时只需对顶部的一层硅材料进行刻蚀,不需在光刻步骤进行对准和套刻,工艺简单易行。该截线滤波器由一截突柱波导与直波导耦合组成,并采用三维时域有限差分方法对其频谱响应进行模拟计算。计算结果表明该滤波器与现有文献中的二维金属-绝缘体-金属波导截线滤波器具有类似的频谱特性。另外,还进一步分析了截线部分及波导自身尺寸对器件输出频谱的影响。     

金膜上亚波长小孔阵列表面等离激元颜色滤波器偏振性质

金属薄膜上制备的表面等离激元颜色滤波器具有很强的颜色可调性. 在200 nm厚的金膜上, 通过聚焦离子束刻蚀, 制备一系列周期逐渐变化的圆形、方形、矩形亚波长尺寸小孔方阵列表面等离激元颜色滤波器, 改变入射光的偏振方向, 观察其超透射滤波现象. 研究发现: 对于矩形小孔阵列, 其透射光颜色随入射光偏振方向的变化而改变; 而对于圆形、方形的小孔阵列, 其透射光颜色对入射光的偏振方向并不敏感. 分析表明, 对于金膜上刻蚀的小孔结构, 虽然结构的周期性导致的表面等离激元极化子会对透射光的颜色变化产生一定影响, 但是随小孔形状变化的局域表面等离激元共振才是影响透射光颜色的决定性因素. 如果入射光没有在小孔中激发出局域表面等离激元, 则表面等离激元极化子对透射光的影响也会消失. 根据不同形状小孔周期结构透射光颜色随入射光的偏振变化特点, 制备出了包含两种小孔形状的复合周期结构. 随着入射光偏振方向的改变, 该结构会显示出不同的颜色图案. 关键词： 表面等离激元极化子 局域表面等离激元 颜色滤波器 亚波长小孔阵列     

Soliton excitation in the pass band of the transmission line based on modulation

We numerically investigate the excitation of soliton waves in the nonlinear electrical transmission line formed by many cells. When the periodic driving voltage with frequency in the pass band closing to the cutoff frequency is applied to the endpoint of the whole line, the soliton wave can be generated. The numerical results show that the soliton wave generation mainly depends on the self modulation associated with the nonlinear effect. In this study, the lower subharmonic component is also observed in the frequency spectrum. To further understand this phenomenon, we study the dependence of the subharmonic power spectrum and frequency on the forcing amplitude and frequency numerically, and find that the subharmonic frequency increases with the gradual growth of the driving amplitude.     

A numerical analysis on the homogenous property for integrated narrow band pass filter

The integrated narrow band pass filter is an important photonic device. The performance of this device is limited by the two problems, absorption coefficient and thickness homogeneous in the resonant cavity layer. We have developed a numerical simulation method to analyze the factors’ influence on the behavior of integrated filters. It is found that the non-homogeneous of layer thickness will play a dominance role in the property of band width of transmission spectra of the 32-chanels integrated narrow band pass filter device in near infrared.     

带通滤波器对能见度测量不确定度的影响

在能见度测量中,为了抑制环境光变化对测量不确定度的影响,在光发射端对探测光束进行调制,在接收端对探测到的光电信号进行带通滤波。带通滤波器的特性参数受到工作环境温度变化的影响,导致频响函数变化,从而引入能见度测量的不确定度。以二阶有源带通滤波器为例,从传输函数入手分析了带通滤波器频响幅度随温度变化的规律,实验测定了频响幅度随温度变化的关系。结果表明:在高能见度天气状况下,在15 ℃~40 ℃温度范围内,环境温度每变化1 ℃,带通滤波器将贡献约4.5%的不确定度;低能见度时,带通滤波器的影响比高能见度时小得多。     

Nonlinear dynamic analysis and surface sliding mode controller based on low pass filter for chaotic oscillation in power system with power disturbance

Chaotic oscillation in the power system often poses a great threat to the stability of the power grid, and the dynamic behaviors of fourth-order power system with power disturbance, which is more in line with the actual situation, are investigated firstly through Lyapunov exponent spectrums and bifurcation diagrams. It is found that the power system with power disturbance has more complex dynamic behaviors and larger domains of chaos. The disturbance terms also result in dynamic behaviors different from those of power system without disturbance, which sometimes brings system motions to period orbits with perturbation-related parameters limited in specific range. Moreover, a dynamic surface sliding mode controller with low pass filter is designed for chaotic suppression, and the relay characteristic function is selected as switching function to inhibit high-frequency chattering. Numerical simulations show that the sliding mode controller owns good effectiveness and strong robustness.     

SHF频段超宽带高温超导滤波器的研制

针对超宽带通信系统的发展趋势,采用1/4波长短截线结构设计了一个工作于超高频(SHF)频段的超宽带高温超导滤波器,滤波器的中心频率为4.2 GHz,相对带宽为50%,讨论了1/4波长短截线结构滤波器的设计原理,给出了所设计超宽带滤波器的理论曲线、模拟仿真结果。实际制作的超宽带高温超导滤波器的测量曲线与模拟仿真曲线基本吻合,得到了满意的结果。     

Plasmonic Fraunhofer-wavelength narrow-band filter based on calcium film

We theoretically investigate plasmonic properties of a calcium film in a Kretschmann excitation scheme. Based on surface plasmon polaritons, the absorbance of the calcium film can be as high as 100% for the p-polarization, much higher than the absorbance for the s-polarization at the wavelength of 422.7 nm, correspondingly to the g Fraunhofer line. The 45 nm thick film of calcium has a high reflectance of about 76% at 422.7 nm for s-polarization. But for p-polarization, there is a minimum in the reflectivity curves at the angle of 19°. The narrow-band filter based on calcium film is particularly suited for working with conventional calcium atomic filter and on-chip integration due to its solid-state bulky feature. Furthermore, the plasmonic filter based on the calcium film is described that may offers new applications in angle- and polarization-sensitive sensor and the detection of weak laser light.     

An incident-direction-selective transmission filter based on anisotropic metamaterial

We construct an incident-direction-selective transmission filter based on anisotropic metamaterial, and explore the possibility of complete tunneling when elements of permittivity and permeability tensors of the anisotropic metamaterial are totally or partially negative. We first deduce the expressions of field distribution, reflection and transmission amplitudes in our filter and then study the influence of anisotropic metamaterial on the tunneling incident angle of light, including seven subcases of different combinations of positive and negative permittivity and permeability components. At last we conclude the principle of appearance of complete tunneling.     

Polarization controllable spatial filter based on azo-dye-doped liquid-crystal film

This investigation establishes the feasibility of exploiting the surface-assisted photoalignment effect in dye-doped liquid-crystal (DDLC) films as spatial filters with controllable polarization in optical signal processing. The fabrication relies on the fact that the various intensities of the diffracted orders are responsible for various changes of the polarization state induced by the photoaligned DDLC film. Specific spatial orders in Fourier optical signal processing can be filtered by use of an analyzer placed behind the sample to control the polarization state of the diffracted orders. A simulation was performed, and the results agree closely with the experimental data.     

基于透射谱的GaN薄膜厚度测量

通过对蓝宝石衬底异质外延GaN薄膜光学透射谱的分析，结合晶体薄膜的干涉效应原理并考虑折射率随光子波长变化的影响，从理论上推导出了实用的薄膜厚度计算方法. 实际应用表明，该方法是一种快速准确的GaN薄膜厚度测量方法. 关键词： GaN 透射谱 厚度测量