共查询到20条相似文献,搜索用时 15 毫秒
1.
S. Bugaychuk G. Klimusheva Y. Garbovskiy T. Mirnaya A. Ischenko 《Opto-Electronics Review》2006,14(4):275-279
The dynamic holography in new composite materials based on a novel class of metal-alkanoate ionic liquid crystals (ILCs) is
studied experimentally and theoretically. The composites are formed as a dielectric dye film covered by lyotropic metal-alkanoate
ILC and ionic smectic glasses with doped dye molecules. The dynamic gratings are created by nanosecond pulses of double frequency
Nd:YAP laser, the recording demonstrates fast erasure time of residual thermal gratings. The nonlinear optical properties
are determined by the resonance nonlinearity in photosensitive centres of ILC. Note, that permanent relief gratings will be
formed on a dielectric dye film only as well as in composite cells either with nematic LC or with polymers under action of
pulsed laser radiation. Lyotropic ILC layer applied over the dye film provides the dynamic regime of grating recording in
composite cells. We found a secondary thermal grating is much smaller, the conductive ILC matrix provides effective heat dissipation
and erasure of this thermal grating. A theory of Raman-Nath self-diffraction holography on thin films followed from the wave
equation and the nonlinear mechanism of absorption saturation is developed to explain experimental results. 相似文献
2.
研究了两束相干光以相同的入射角从左、右两侧分别入射到Au-SiO_2复合介质板时,在不同的体系参数下该复合材料体系发生相干完美吸收的情形.运用有效媒质理论推导出了复合介质的有效介电常数以及有效磁导率;在得到有效电磁参数的基础上进一步推导得到平面波入射复合介质板时的反/透射系数.通过比较分析非局域和局域情况下颗粒复合介质的相干完美吸收现象,发现当颗粒尺寸很小时非局域效应的影响会导致复合介质产生相干完美吸收的入射光的频率范围显著变宽.在进一步的解析计算中,通过调节复合介质板的厚度、入射光波长、金属颗粒体积分数等参数得到了不同情况下产生的相干完美吸收现象,并由此分析非局域情形下对于相干完美吸收现象的调控. 相似文献
3.
Large Positive and Negative Lateral Displacements from Total Internal Reflection Configuration with a Weakly Absorbing Dielectric Film
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It is theoretically shown that the simultaneously large positive and negative lateral displacements will appear when the resonant condition is satisfied for a TE-polarized light beam reflected from the total internal reflection configuration with a weakly absorbing dielectric film. Appearance of the enhanced negative lateral displacement is relative to the incidence angle, absorption of the thin film and its thickness. If we select an appropriate weakly absorbing dielectric film and its thickness, the simultaneously enhanced positive and negative lateral displacements will appear at different resonant angles. These phenomena may lead to convenient measurements and interesting applications in optical devices. 相似文献
4.
Gupta SD 《Optics letters》2007,32(11):1483-1485
I study a multilayered medium consisting of a metal-dielectric composite film, a spacer layer, and a dielectric Bragg reflector. I demonstrate a greater flexibility over the critical coupling phenomenon [Tischler et al., Opt. Lett. 31, 2045 (2006)], whereby nearly all the incident light energy is absorbed by the composite film through suppression of both transmission and reflection from the structure. For a larger volume fraction of the metal inclusions, strong light-matter coupling is shown to lead to almost total absorption at two distinct frequencies. 相似文献
5.
金属纳米粒子利用其局域表面等离子体共振效应(LSPR),可以增强附近荧光分子的自发辐射速率,因而在光学传感、光电器件等领域中具有潜在的应用价值.金属纳米粒子的LSPR与其自身的材料、形状、尺寸以及周围环境介质密切相关,这影响着纳米粒子在具体器件中的应用.本文利用三维时域有限差分法,研究了相同体积的球形、椭球形、立方形与三棱柱形银纳米粒子对薄膜发光二极管辐射功率的影响;计算了不同形状银纳米粒子对偶极子光源辐射功率和薄膜器件光出射强度的增强,并结合LSPR效应讨论了辐射功率变化的物理机理.研究结果表明:银纳米粒子自身形状尖锐程度的增加有利于提高LSPR的共振强度;同时纳米粒子的形状影响了LSPR共振电场与薄膜器件中偶极子辐射电场之间的耦合作用,其中立方形纳米粒子因为能实现最强的耦合作用而对器件的辐射功率增强最大.在此基础上进一步讨论了不同薄膜材料对LSPR共振及光源辐射功率的影响,发现较高的材料折射率有利于增强金属纳米粒子的LSPR与器件的耦合作用,从而改善发光二极管性能. 相似文献
6.
A. L. Stepanov 《Optics and Spectroscopy》2011,111(2):215-219
The effect of nanosecond excimer laser pulses on a composite layer of sodium-calcium silicate glass with silver nanoparticles
has been investigated. Nanoparticles were synthesized by ion implantation. Based on measuring the optical absorption and reflection
spectra of the composite layers, it is found that an increase in the number of laser pulses leads to a monotonic decrease
in the size of silver nanoparticles. However, laser irradiation with a longer duration leads to the growth of nanoparticles
with their subsequent destruction. The effects observed are discussed in terms of heating a glass composite layer as a result
of the effective absorption of laser radiation. 相似文献
7.
8.
基于角谱理论的厚层光刻胶衍射光场研究 总被引:7,自引:1,他引:6
为快速、准确地获得厚层光刻胶内部衍射光场的分布,利用角谱理论的思想,考虑入射光通过掩模后在光刻胶面的反射、透射和光刻胶曝光过程中其折射率及吸收系数在深度方向上的变化,建立了衍射光场在厚层光刻胶中传输的理论模型。为减小计算量,对快速傅里叶算法进行了改进。该方法数值计算速度快,计算结果准确,并适用于光在折射率渐变的其它介质中的传播。最后,对厚层光刻胶中光场分布进行了数值模拟;计算模拟表明,对于厚层光刻胶,其表面的反射、透射和折射率及吸收系数在深度方向变化对衍射光场分布有明显的影响。 相似文献
9.
10.
The dependences of the absorptivity of a nanocomposite layer (a dielectric matrix with spherical metal inclusions) on the frequency, the volume fraction, the size of inclusions, the thickness of the layer, and the angle of incidence of the wave on it are studied. It is shown that the particular features of optical characteristics are related with the plasmon resonance in nanoparticles and the resonant-frequency dependence of the dielectric permittivity of the composite medium. The values of film parameters and frequency intervals in which the incident radiation is absorbed almost completely are found. 相似文献
11.
F. Mattioli M. Ortolani S. Lupi O. Limaj R. Leoni 《Applied Physics A: Materials Science & Processing》2011,103(3):627-630
We report on the fabrication and optical properties of thin metal films periodically patterned with square hole arrays of
2 micron pitch, which behave as substrateless plasmonic devices at mid-infrared frequencies. Large (3×3 mm2) meshes were fabricated by metallizing a patterned silicon nitride membrane. The mid-infrared spectra display resonant absorption
lines with a Q-factor up to 22 in both transmission and reflection, due to the interaction of the radiation with surface plasmon
modes on both faces of the film, allowed by substrate removal. The devices can be used to fabricate surface plasmon-based
chemical sensors employing mid-infrared radiation. 相似文献
12.
13.
设计了一种基于一阶Minkowski分形双方环(Minkowski fractal double square loop, MFDSL)电谐振器结构与电阻膜复合的超薄、 宽频带、极化不敏感和宽入射角的超材料吸波体. 该吸波体的基本结构单元由MFDSL电谐振器结构、方块电阻膜、电介质基板和金属背板组成. 采用时域有限差分算法对这种复合结构吸波体的电磁波吸收特性进行数值模拟分析. 模拟得到的反射率和吸收率表明: 该吸波体在7.5-42 GHz之间对入射电磁波具有大于90%以上的强吸收特性. 模拟得到的不同极化角和不同入射角下的吸收率表明: 该吸波体具有极化不敏感和宽入射角特性. 进一步的数值模拟结果表明, 该复合结构吸波体对电磁波的吸收主要是基于电磁谐振和电路谐振机制, 通过方块电阻的设计可以实现工作频率范围的调节.
关键词:
电阻膜
分形频率选择表面
宽频带吸收 相似文献
14.
The optical modes in a dielectric slab are considerably changed by replacing the dielectric medium on one side of the slab by a metal. In particular, the TH mode m = 0 shows the behavior of a surface plasma wave. The modes were excited in a reflection experiment by the use of prism film coupling in an Al-LiF-air system, the results are in satisfactory agreement with theory. 相似文献
15.
A. D. Zamkovets S. M. Kachan A. N. Ponyavina N. I. Sil'vanovich 《Journal of Applied Spectroscopy》2003,70(4):593-598
The results of theoretical and experimental investigations of the optical spectra of layer-periodic nanocomposites consisting of alternating tightly packed monolayers of silver nanoparticles and separating KCl layers of subwave thickness are presented. The characteristic features of the spectral dependence of the transmission and reflection coefficients of this type of nanocomposites have been analyzed for the case where the photon forbidden bands are located near the plasmon-absorption band. Experimental samples were prepared by successive thermal evaporation of silver and KCl in vacuum. Theoretical calculations were carried out using the quasi-crystalline approximation of the theory of multiple scattering of waves. It is shown that the spectral position, shape, and intensity of absorption and reflection bands can be regulated by changing the optical thickness of the intermediate dielectric films in a layered metal-dielectric composite. 相似文献
16.
ZnO薄膜光学常数测量 总被引:7,自引:0,他引:7
利用Kramers-Kronig方法(K-K方法)测量了ZnO薄膜的复介电常数和复折射率(折射率和消光系数)。为了满足K-K方法所要求的条件,光源发出的光束通过一个特殊设计的中间带孔的反射镜垂直投射到ZnO薄膜表面,在ZnO薄膜表面产生的反射光穿过反射镜中间的小孔进入单色仪,从而测量出正入射情况下ZnO薄膜的反射光谱。对有限波段下测量的数据经合理的外推后,得出全波段的薄膜反射谱,然后利用K-K方法计算出ZnO薄膜的复介电常数和复折射率。实验结果表明,氧化锌薄膜在可见光范围内的折射率近似为一常数3.5;在430nm附近出现折射率最大值,而在短波长范围所对应的折射率大大降低,其值在0.5—2.5之间起伏波动。 相似文献
17.
在热镀锌钢板表面制备了硅烷钒锆复合钝化膜。用X射线光电子能谱(XPS)、射频辉光放电发射光谱(rf-GD-OES)和傅里叶变换衰减全反射红外光谱(ATR-FTIR)表征了钝化膜的组成结构,分析了硅烷钒锆复合钝化膜的成膜机理。结果表明:硅烷之间互联构成了硅烷钒锆复合钝化膜的主成膜成分,无机缓蚀剂均匀分布在膜层中。钝化膜表面Si2p的XPS窄幅扫描谱100.7 eV处的拟合峰和红外光谱在波数1 100 cm-1 Si—O吸收峰变宽加强,表明硅烷以Si—O—Zn键的形式化学吸附在锌的表面,硅烷分子之间通过Si—O—Si键相互交联;红外光谱中1 650和1 560 cm-1的两个酰胺特征峰,结合910 cm-1的环氧特征峰的消失,表明γ-GPT的环氧基团在氨基活性氢的诱导下开环和γ-APT的氨基之间发生聚合反应形成交联的空间网状结构;rf-GD-OES分析发现钝化膜0.3 μm处存在一层富氧层,钝化反应生成的ZrF4,ZrO2和钒盐等无机物均匀分布在钝化膜中。分析膜层组成结构和成膜前后的ATR-FTIR光谱,研究了成膜过程中发生的物理过程和化学变化,提出了硅烷钒锆复合钝化膜的成膜机理。 相似文献
18.
Yu. S. Dadoenkova I. L. Lyubchanskii Y. P. Lee T. Rasing 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,71(3):401-406
We investigate the light reflection from a nonlinear
optical dielectric film on a bigyrotropic magneto-electric
substrate magnetized parallel to the interface. The reflection
matrix has been obtained and reflection coefficients are
investigated with respect to the incidence angle for both
polarizations of the incident light. We analyzed the optical
nonlinearity and the magnetoelectric coupling contributions to the
reflection of the electromagnetic waves and the appearance of
so-called pseudo-Brewster angles. 相似文献
19.
T. A. Vartanyan N. B. Leonov A. E. Logunov S. G. Przhibel’skiĭ V. V. Khromov 《Optics and Spectroscopy》2007,102(5):728-733
The morphological characteristics of ensembles of metal nanoparticles on transparent dielectric substrates have been studied by the methods of hole-burning and linear absorption spectroscopy. The size and shape of particles were changed under the exposure to the optical radiation that induced photodetachment of atoms and their photostimulated diffusion over the surface of nanoparticles. The correlation between holes burned in different absorption bands is explained by the morphological features of the island film. The relaxation times of individual modes of collective plasma oscillations and the shape parameters of particles modeled by three-axial ellipsoids have been determined. 相似文献
20.
The reflection of linearly polarized light from an ultrathin anisotropic dielectric film on isotropic absorbing substrate is investigated analytically in the long-wavelength limit. All analytical results are correlated with the numerical solution of the anisotropic reflection problem on the basis of rigorous electromagnetic theory. Simple analytical approach developed in this work not only gives a physical insight into the reflection problem but also provides a way of estimating the necessary experimental accuracy for optical diagnostics by reflection characteristics. It is shown that obtained expressions are of immediate interest for determining the parameters of anisotropic surface layers. Innovative possibilities for optical diagnostics of anisotropic properties of ultrathin dielectric layers upon absorbing materials are discussed. 相似文献