共查询到20条相似文献,搜索用时 218 毫秒
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纳米多孔光波导漏模共振传感器的折射率灵敏度分析(英文) 总被引:1,自引:0,他引:1
在玻璃基片上射频溅射50 nm厚的金膜,然后利用TiO2胶体溶液在金膜表面制备了厚度约为320 nm的TiO2纳米多孔薄膜.以此双层膜为漏模光波导芯片,构建了基于Kretschmann结构的波长调制型光波导漏模共振(LMR)传感器.利用扫描电子显微镜(SEM)观测了TiO2纳米多孔薄膜的表面和横截面形貌.实验研究了在纳米多孔光波导中给定漏模的共振波长及折射率灵敏度与入射角的依赖关系.结果表明,随着入射角的增大,共振波长逐渐蓝移,折射率灵敏度随之下降.此外,与传统的表面等离子体共振(SPR)传感器进行了对比,结果表明在相同的共振波长下,纳米多孔光波导LMR传感器折射率灵敏度大于SPR传感器. 相似文献
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挠性波导管在生产过程中经常出现波导管齿形不规则、缩齿困难以及齿根撕裂的问题.以H68黄铜挠性波导管为例,通过对影响其质量的壁厚、软化退火工艺、酸洗工艺、滚齿模结构和钎焊工艺等因素进行了分析,得知造成以上缺陷的主要原因是毛坯管壁厚超差、滚齿模结构引起滚压轮同齿条啮合过紧、间隙不均以及退火温度选择不当.最后通过对H68黄铜... 相似文献
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阵列波导光栅解复用器光谱响应特性分析 总被引:1,自引:0,他引:1
基于单模光波导本征模场及其端面衍射场分布的高斯近似表达,推导出两个端面非接触光波导耦合的耦合系数的函数表达式,并基于此推导出阵列波导光栅解复用器的简单光谱响应效率的函数表达式。建立了分析阵列波导光栅解复用器光谱响应特性的简洁数学模型,阐明了阵列波导光栅解复用器对通道中心频率的响应度和相邻信号通道间的串扰与基本参数的关系,为设计和分析阵列波导光栅解复用器提供了理论基础。 相似文献
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一种新颖的偏振不敏感的阵列波导光栅 总被引:2,自引:2,他引:0
提出了一种新颖偏振不敏感的阵列波导光栅(AWG)。器件的输入端增加了一个全光学偏振自动控制器(AOPSC),可将注入AWG的随机偏振的输入光转换为与AWG中TE0模偏振方向相同且功率损耗很小的线偏振光。AWG结构设计采用非对称的平面波导,包层与波导芯层的相对折射率差为0.7%,波导芯层的宽厚比要高,可以消除TE与TM模的简并,使波导中只能激励TE0模,而使TM0模截止。这种AWG结构完全消除了不同偏振态信号光对AWG工作性能的影响,从而使器件对偏振不敏感。设计的8×0.8nm器件整体尺寸为2cm×1cm,串扰优于-30dB,最大插入损耗为4.2dB。 相似文献
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由于弱调制光栅可以等效为平面波导,本文从平面波导的本征方程出发,导出垂直入射时弱调制光栅共振位置的表达式.分别以单层、双层膜系导模共振光栅结构为例,研究了光栅层厚度、周期、占空比对共振波长的影响.结合光学薄膜理论设计出一种窄带导模共振负滤光片.由于导模共振对入射波参数和光栅参数都极为敏感,具有窄带效应,用来制作窄带负滤波片非常可行. 相似文献
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Two new asymmetric slab optical waveguides with a left-handed media (LHM) cover or substrate are studied. The effective thickness is derived by using normalized waveguide parameters. An analytical method is then proposed to calculate the universal effective thickness. We show that negative effective thickness exists in the waveguide with a LHM substrate, unlike in conventional waveguide or other LHM waveguides studied previously. However, for the waveguide with a LHM substrate, the shape of high-order mode behaves like that of a traditional slab waveguide, and neither the fundamental mode nor the other higher order modes have the novel phenomena of negative effective thickness. Both TE and TM modes are discussed. 相似文献
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光波在由左手材料和激活介质构成的光子晶体中的传输 总被引:1,自引:0,他引:1
用特征矩阵法计算了光波在包含左手材料和激活介质的一维光子晶体中的传播规律,当左手材料和激活介质厚度相等时,出现了超窄通带和透射率大于1的高增益现象,受激辐射的增强总是发生在带隙的边缘附近。进一步论证了受激辐射增强现象与光子带隙边缘群速度异常存在关联。随着频率的增加,光增益呈e指数增大。光频率不变时,光在光子晶体中的透射率随光子晶体周期数的增加呈线性增加。当左手材料和激活介质厚度不相等时,通带宽度增加,带边仍存在大于1的透射峰。 相似文献
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The transmission and reflection characteristics are presented of a one-dimensional (1D) left-handed metamaterial (LHM) and its constituents, split ring resonator and thin wire arrays. A well-defined left-handed transmission band with a peak value of -7.2 dB is obtained at frequencies where effective permittivity and permeability are both negative. A sharp dip (-34.5 dB) at the reflection spectrum of 1D ordered LHM is observed. The frequency of ultra-low reflection did not change considerably for another LHM with a different thickness, meaning that the low reflection is not because of the thickness resonance but rather the impedance-matching of LHM at the surface. Disorder in LHM structures is shown to affect the reflection characteristics 相似文献
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Monzon C Forester DW Smith D Loschialpo P 《Journal of the Optical Society of America. A, Optics, image science, and vision》2006,23(2):339-348
An exact analytical solution to the problem of plane-wave diffraction by a penetrable left-handed medium (LHM) epsilon = micro = -1 wedge of arbitrary angle (subject to valid physical constraints) is presented. Standard analysis involving discontinuous angular eigenfunctions and even/odd symmetry decomposition resulted in a discrete spectrum leading to a series solution resembling the traditional perfect electric conductor wedge solution but exhibiting the expected negative refraction phenomenology. Numerical results are presented, some of which seemed paradoxical but are explainable by classical means. A new type of illusory edge radiation is observed and explained. Also, a novel edge-launched interface standing wave is observed on the directly illuminated side. The exact analytical solution is verified by comparison with finite-difference time-domain simulation on causal LHM materials. 相似文献
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Keqing Lu Wei Zhao Yanlong Yang Yang Yang Xueming Liu Yanpeng Zhang 《Journal of Modern Optics》2013,60(15):2137-2151
Waveguides induced by one-dimensional spatial photovoltaic solitons are investigated in both self-defocusing-type and self-focusing-type photorefractive photovoltaic materials. The number of possible guided modes in a waveguide induced by a bright photovoltaic soliton is obtained using numerical techniques. This number of guided modes increases monotonically with increasing intensity ratio, which is the ratio between the peak intensity of the soliton and the sum of the background illumination and the dark irradiance. On the other hand, waveguides induced by dark photovoltaic solitons are always single mode for all intensity ratios, and the higher the intensity ratio, the more confined is the optical energy near the centre of the dark photovoltaic soliton. Relevant examples are provided where photorefractive photovoltaic materials are of self-defocusing and self-focusing types. The properties of soliton-induced waveguides in both self-defocusing-type and self-focusing-type materials are also discussed. 相似文献
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Scattering properties of an impedance-matched, ideal, homogeneous, causal "left-handed" sphere 总被引:1,自引:0,他引:1
Monzon C Forester DW Medgyesi-Mitschang LN 《Journal of the Optical Society of America. A, Optics, image science, and vision》2004,21(12):2311-2319
The plane-wave scattering properties of a sphere of material having an ideal, homogeneous, and causal permittivity epsilon(f), and permeability mu(f) were investigated through detailed three-dimensional finite-difference time-domain, method-of-moments, and series-solution simulations. A Lorentzian functional form was chosen for epsilon(f) and mu( f), as it yields causal responses and allows us to study the physics of the left-handed-medium (LHM) regime. Our interest lies mainly in the frequency range where negative refraction [Re(n) < 0] is observed. We found that when operating in the LHM regime, an impedance-matched sphere responds with scattering features strikingly different from those found in ordinary materials. In particular, we found zero back-scattering and forward scattering that exceeds that of a metal sphere of similar size. The equality of E- and H-plane patterns was proved analytically and numerically, and the possibility of internal subwavelength focusing with a zero index sphere is also reported. 相似文献
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Safaai-Jazi A Claus RO 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1988,35(5):619-627
A perturbation analysis of guided and leaky modes in fiber acoustic waveguides with core and cladding parameters that are slightly different is presented. The perturbing parameter is the shear-velocity difference between the core and cladding material epsilon(s). Acoustic fields and eigenvalues are expanded in power series of epsilon (s)(1/2) for radial and flexural modes and in powers of epsilon(3) for torsional modes. Expansion of leaky longitudinal modes is also in terms of epsilon(s), but the nature of perturbation analysis for these modes is somewhat different from that of guided modes. Zero-order solutions for all types of modes are obtained, and some important higher-order effects are discussed. Common features of optical and acoustic modes in weakly guiding fibers are addressed. It is shown that with respect to zero-order solutions of guided modes, optical and acoustic fibers have identical propagation characteristics. Exact and zero-order propagation characteristics for several lower-order shear-type modes are calculated and compared. 相似文献
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Gong X Han M Shang X Xiong J Duan J Sekimoto H 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2007,54(6):1171-1176
In this paper, a hybrid method, which combines the traditional concept of guided waves and the finite element method (FEM), is proposed to analyze the spurious modes of aluminum nitride (AIN) film with electrodes. First, the guided wave modes in the plated area are obtained by 1-D FEM. Second, a mode-match method is used to satisfy the boundary conditions. The vibration of the film resonator is a superposition of all of the guided modes. With respect to an A1N film resonator, which is a thickness-stretch mode resonator, we have identified three families of spurious modes: extension, thickness-stretch, and thickness-shear. The spectrum of spurious modes is calculated and the influence of the spurious modes is discussed. 相似文献
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Debo Hu Ke Chen Xinzhong Chen Xiangdong Guo Mengkun Liu Qing Dai 《Advanced materials (Deerfield Beach, Fla.)》2019,31(27)
van der Waals (vdW) crystals are promising candidates for integrated phase retardation applications due to their large optical birefringence. Among the two major types of vdW materials, the hyperbolic vdW crystals are inherently inadequate for optical retardation applications since the supported polaritonic modes are exclusively transverse‐magnetic (TM) polarized and relatively lossy. Elliptic vdW crystals, on the other hand, represent a superior choice. For example, molybdenum disulfide (MoS2) is a natural uniaxial vdW crystal with extreme elliptic anisotropy in the frequency range of optical communication. Both transverse‐electric (TE) polarized ordinary and TM polarized extraordinary waveguide modes can be supported in MoS2 microcrystals with suitable thicknesses. In this work, low‐loss transmission of these guided modes is demonstrated with nano‐optical imaging at the near‐infrared (NIR) wavelength (1530 nm). More importantly, by combining theoretical calculations and NIR nanoimaging, the modal birefringence between the orthogonally polarized TE and TM modes is shown to be tunable in both sign and magnitude via varying the thickness of the MoS2 microcrystal. This tunability represents a unique new opportunity to control the polarization behavior of photons with vdW materials. 相似文献