共查询到20条相似文献,搜索用时 46 毫秒
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Deliberately introducing defects into photonic crystals is an important way to functionalize the photonic crystals. We prepare a special large-scale three-dimensional(3D) photonic crystal(PC) with designed defects by an easy and low-cost method. The defect layer consists of photoresist strips or air-core strips. Field emission scanning electron microscopy(FESEM) shows that the 3D PC is of good quality and the defect layer is uniform. Different defect states shown in the ultraviolet-visible spectra are induced by the photoresist strip layer and air-core strip layer. The special large-scale 3D PC can be tested for integrated optical circuits, and the defects can act as optical waveguides. 相似文献
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We propose a type of photonic heterostructure by combining dielectric one-dimensional (1D) defective photonic crystals (PCs)
and magnetic 1D defective PCs. Both of the two PCs consist of alternating positive-index-material (PIM) layers with a negative-index-material
(NIM) defect layer. It is demonstrated by transfer matrix method that there is a polarization- and direction-independent defect
mode in a wide incident-angle range within Bragg gaps in the heterostructure. The field distributions prove that the dielectric
1D defective PC benefits to achieve the approximately omnidirectional defect mode for TE waves while the magnetic 1D defective
PC benefits for TM waves. Such a structure is useful for designing polarization-independent and omnidirectional or large incident
angle narrow-passband filters in optical devices. 相似文献
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用一维光子带隙结构增强硫化镉双光子吸收研究 总被引:2,自引:2,他引:0
用真空镀膜方法制备了含有单个CdS缺陷层的具有不同周期和结构参量的TiO2/SiO2一维光子晶体。用抽运一探测技术研究了CdS缺陷层的双光子吸收(TPA)现象。实验结果表明:一维光子晶体中CdS缺陷层的双光子吸收显著增强。不同周期和结构参量的一维光子晶体中CdS缺陷层的双光子吸收系数不同。双光子吸收的增强来源于由光局域化导致的缺陷层的电场强度的增加。缺陷层电场强度与一维光子晶体的结构有关,如周期,光子带隙的位置与宽度及缺陷模式等因素都会影响缺陷层电场强度。采用四分之一波长的高低折射率介质层和与入射波长匹配的缺陷模可以得到最大的缺陷层电场强度。 相似文献
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The propagation of guided waves in photonic crystal fibers (PCFs) is studied. A photonic crystal fiber can be regarded as
a perfect two-dimensional photonic crystal (PC) with a line defect along the axial direction. Under the assumption that the
background spectrum has gaps, we give a simple condition on the parameters of the medium and of the line defect, which ensures
the rise of eigenvalues in a specified subinterval of the given gap of the photonic crystal fiber. Using the modified Combes-Thomas
estimates, we prove that the eigenfunctions corresponding to the eigenvalues decay exponentially away from the line defect.
The work was supported by the NSFC (10431030) of China.
D. Miao is currently visiting Department of Mathematics, Michigan State University, USA. 相似文献
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The computer-generated holography technique is applied to the structuring of two-dimensional (2D) photonic crystals with inherently embedded arbitrary defects. The technique uses phase-only Fourier gratings as a generator of spot arrays in the focal plane, such that a single exposure produces a 2D array of focused spots with desired defects or modifications in the lattice structure. We demonstrate several types of large-area 2D lattice structures with square, hexagonal, or hybrid lattices embedded with point and (or) line defects. Scanning the Fourier plane in the depth direction throughout multiphoton polymerization media allows 3D lattices with stacked defect layers to be formed. 相似文献
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It is shown that superprism effect can be observed not only in 2D and 3D photonic crystal but also in 1D photonic crystal. To observe the effect a diffraction grating should be put on the top of the 1D PC. It is shown that the band gap more dramatically appears in 1D PC than in 2D PC. This effect makes all PBG effects including superprism effect more pronounced and also weakens the influence of losses. 相似文献
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采用Si和SiO2两种介质材料构造一维缺陷光子晶体,缺陷层介质为Si,利用传输矩阵法对带有缺陷的一维光子晶体的传光特性进行了理论分析,并得到其带隙特性.由于缺陷的存在,使得光子晶体的透射谱中产生缺陷峰.当被测温度变化时,根据两种介质的热光效应和热膨胀效应,光子晶体介质和缺陷层的光学厚度和折射率发生变化,透射谱缺陷峰产生漂移,由缺陷峰的中心波长漂移量得到被测温度的大小.构建了一维缺陷光子晶体测量温度的实验系统,实验结果表明缺陷峰中心波长与光子晶体所受的温度呈线性关系,测量灵敏度为0—2
关键词:
温度测量
一维光子晶体
传输矩阵法
缺陷峰 相似文献
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通常采用含两个耦合参数的紧束缚近似,就能很好地描述光子晶体缺陷因耦合而导致的共振频率分裂.然而,缺陷耦合造成的共振频率移动,即包含奇数个缺陷的耦合系统的中央共振频率位置与原来单缺陷时的共振频率位置存在差异,则只有采用含三个耦合参数的严格紧束缚方法才能正确描述.根据耦合参数与共振频率的关系,利用三缺陷耦合系统的模拟计算结果确定了三个耦合参数的具体值,从而在理论上能够预言由任意个缺陷构成的耦合系统的共振频率的移动和分裂.理论预言与基于有限时域差分法的数值计算完全相符. 相似文献
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We propose a new mechanism for constructing waveguide intersections with broad bandwidth and low cross talk in photonic crystal (PC) circuits. The intersections are created by combination of coupled-cavity wave-guides (CCWs) with conventional line-defect waveguides. This mechanism utilizes the strong dependence of the defect coupling on the field pattern in the defects and the alignment of the defects (i.e., the coupling angle) in CCWs. By properly designing the defect mode, we demonstrate through numerical simulation the establishment of such a waveguide intersection in one of the most useful PCs, which is based on a two-dimensional triangular lattice of air holes made in a dielectric material. The transmission of a 500-fs pulse at ~1.3 microm is simulated by use of the finite-difference time-domain method, showing negligible distortion and low cross talk. 相似文献
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Based on the polystyrene material of low refractive index, light localization in photonic bandgaps of two kinds of 2D octagonal quasiperiodic photonic crystal slabs are investigated in theory, including the air-rod polystyrene slab and polystyrene-rod slab. The properties of bandgaps and localized modes in both two defect-free patterns are analyzed in detail. When a single-point defect is introduced into two quasiperiodic structures, the position of emerging defect modes and the red-shifting of resonant modes in wavelength are observed quite differently when the defect microcavity is increased in size. This difference is caused by the competition of two physical mechanisms, which are the effect of defect energy levels caused by defects introduced into photonic crystals and the resonance of modes in the defect cavity. These results will provide theoretical support for experimental fabrication of organic light-emitting quasiperiodic photonic crystal devices. 相似文献
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We theoretically studied a left-hand structure based on a two-dimensional (2D) photonic crystal (PC)with a negative refractive index. The propagation of electromagnetic waves in the proposed PC structure is investigated through dispersion characteristic analysis and numerical simulation of field pattern. The designed PC structure can exhibit all angle negative refraction, and the corresponding effective refractive indices along all directions are almost same and close to the ideal value of -1. A flat lens formed from such a PC has been designed and its imaging properties have been investigated systematically. 相似文献
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We numerically demonstrate terahertz multichannel filters with independently tunable defect modes based on fractal photonic crystals. Single defect and multiple defects models are proposed to fabricate the multichannel terahertz filters. The facts that the wave functions of the defect states do not overlap and their bases are orthogonal lead to the independency among the defect modes. The simulated results theoretically provide the principle for fabricating independently tunable multichannel terahertz filters by utilizing one-dimensional photonic crystals with defects. 相似文献
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We study the dynamics of 2D gap solitons (GSs) in Bragg resonant nonlinear (photonic) gratings in the presence of localized defects. Previous work [Stud. Appl. Math.115, 209 (2005)] explains the mechanism of trapping the GS-carried energy at a defect via a resonant energy transfer from the GS into defect modes. We derive a finite-dimensional model that describes the evolution of the defect-trapped state as an interaction of linear defect modes and show that this model approximates the full dynamics very well in the regime when moderate amounts of GS energy are trapped. 相似文献
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Hamed Alipour-Banaei Farhad Mehdizadeh Mahdi Hassangholizadeh-Kashtiban 《Optical and Quantum Electronics》2013,45(10):1063-1075
In this paper due to the crucial role of optical demultiplexers in wavelength division multiplexing and dense wavelength division multiplexing applications, we proposed a new mechanism for designing all optical photonic crystal based demultiplexers with 8, 16 and 32 output channels. Our proposed mechanism for wavelength selecting is a resonant defect structure which consists of one central defect and four defects around the central defect. It has been shown that the selected wavelength depends on the radius of the central defect and the distance between the central defect and other four defects. In all the three proposed demultiplexer the channels spacing is less than 1 nm. We used plane wave expansion method for extracting the band structure of the photonic crystal and employed finite difference time domain method for studying the optical properties of the designed devices. 相似文献