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1.
导模共振滤波器由于其高峰值反射率,低旁带反射,窄带以及带宽可控等优良特性引起了人们极大的关注,采用亚波长光栅的导模共振效应可以实现传统基于高低折射率介质的多层膜滤波器所无法实现的特殊功能,在弱调制模式下,其共振带宽可以被压缩到零点几纳米,但是由于介质表面和空气层的菲涅耳反射,使得偏离或者远离共振区时的反射率偏高,根据等效介质理论,亚波长光栅在远离共振区可以被看为均匀的薄膜,本文通过对导模共振光栅进行单层、双层以及三层抗反射设计,有效的降低了导模共振光栅的旁带反射率,从而在可见光波段获得了性能优良的共振滤波
关键词:
导模共振
平面波导
傅里叶模式理论
窄带滤波 相似文献
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带缓冲层的导模共振滤光片反射光谱特性 总被引:3,自引:2,他引:1
将均质多层膜系设计中的缓冲层概念引入到反射导模共振滤光片的设计中,以研究缓冲层的增加对导模共振滤光片反射光谱特性的影响.设计并通过严格的耦合波理论计算了一、二、三、四通道导模共振反射滤光片光谱特性.在膜系设计中增加缓冲层后.随着其厚度的逐渐增加.反射光谱中依次出现二、三、四个窄带反射峰;缓冲层厚度为796.35 nm时.当滤光片光栅层占空比在0.2~O.9范围内、光栅深度在100~200 nm变化时,共振峰的位置、反射率峰值高度几乎不变,保持了很好的多通道滤光片特性. 相似文献
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导模共振滤波器由于其高峰值反射率,低旁带反射,窄带以及带宽可控等优良特性引起了人们极大的关注,采用亚波长光栅的导模共振效应可以实现传统基于高低折射率介质的多层膜滤波器所无法实现的特殊功能,在弱调制模式下,其共振带宽可以被压缩到零点几纳米,但是由于介质表面和空气层的菲涅耳反射,使得偏离或者远离共振区时的反射率偏高,根据等效介质理论,亚波长光栅在远离共振区可以被看为均匀的薄膜,本文通过对导模共振光栅进行单层、双层以及三层抗反射设计,有效的降低了导模共振光栅的旁带反射率,从而在可见光波段获得了性能优良的共振滤波 相似文献
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为实现阵列化、多波长光探测器件的微型化与集成化,设计了一种基于亚波长金属光栅导模共振原理的透射滤光片。利用波导理论分析了二维金属光栅波导对称和非对称两种结构的共振特性,数值仿真分析了光栅各参数如占空比、光栅厚度、侧壁角度等对透射谱线的影响,并给出了结构优化参数范围。研究表明,透射滤光片的峰值波长与半峰全宽(带宽)取决于光栅周期和缓冲层厚度,带宽的调节范围为2~45 nm,最大透射率为81.7%,所设计的滤光片具有偏振无关性,较好地满足了当前微流控芯片、生物传感阵列等微量样品集成化探测的需求。 相似文献
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缓冲层对导模共振滤光片反射光谱截止特性的影响 总被引:1,自引:0,他引:1
提出将均质多层膜系设计中的缓冲层概念71入到反射导模共振(GMR)滤光片的设计中,通过严格的耦合波理论精确计算,研究了加入缓冲层对改善导模共振滤光片反射峰边带截止深度及截止宽度的作用.双层导模共振滤光片结构中,入射光为TE偏振光时,设计增加97.5 nm缓冲层后,能够明显地展宽反射光谱范围.由原来的192.4 nm展宽到345.6 nm,并且在650~1250 nm波长范围内的边带截止度均比不含缓冲层结构的要深.入射光为TM偏振光,以类似TE结构的滤光片在布儒斯特角入射时,在700~1300 nm波长范围内,较不含缓冲层的结构,也能够获得更宽的截止带反射光谱和更深的截止度.在提出的膜系结构中,经过优化膜系、选择合适的光栅参数等,可以使反射光谱具有更好的截止特性,同时保证设计的共振峰位置不变. 相似文献
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双层交叉叠合式共振亚波长光栅 总被引:2,自引:1,他引:1
提出了一种防伪光栅结构-双层交叉叠合式共振亚波长光栅,其特点是可以展宽共振亚波长光栅的共振波长宽度,使得当将其应用于防伪时能得到更佳的光变效果。分析了半峰全宽展宽的原理,指出共振宽度值的大小依赖于耦合到光栅波导层内一级衍射光的能量。优化设计了此种光栅的结构参量。用矢量衍射理论对该结构的共振特性和制作工艺误差进行了研究。研究表明:这种防伪光栅的共振光谱峰值并不随着入射角的改变而降低,共振半峰全宽最大值约为同等条件下基本共振光栅结构的7倍,该结构的共振性能对光栅制作误差不是很敏感,是一种应用价值较高的防伪光栅结构。 相似文献
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导模共振光栅是一种典型的平面波导共振结构,可在光栅表面或波导层内形成较强的局域电场,能增强光与物质的相互作用.本文在导模共振结构的光栅层和基底层之间,引入低折射率的多孔二氧化硅间隔层,显著增强了局域电场与增益介质的接触度.结果表明,引入多孔二氧化硅后,共振产生的电场增强区域上移至激光染料层,增加了激光染料与电场的相互作用,实现了激光出射增强.本文基于时域有限差分法,对结构参数进行分析优化,研究了820 nm共振波长激发下的出射激光特性,得到了连续的激光出射,其能量阈值约为2.5 mJ/cm^2,线宽约为0.3 nm.本文提出的结构实现了对表面局域电场的有效调控,增强了激发光与增益介质的相互作用,不但可应用于激光器,还为其它发光器件的设计提供了参考. 相似文献
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Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide 总被引:1,自引:0,他引:1
Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs. 相似文献
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A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users. 相似文献
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S. G. Nedel’ko M. A. Krysyuk A. L. Apanasenko L. N. Lymarenko Z. T. Moroz 《Journal of Applied Spectroscopy》1997,64(1):55-61
Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped
with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly
described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation
(5.5·104 Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum
cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics
of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure
crystals is analyzed (preliminarily).
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997. 相似文献
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A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output. 相似文献
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The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper. 相似文献
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We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed. 相似文献
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Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell. 相似文献
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A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques. 相似文献
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Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing. 相似文献