共查询到19条相似文献,搜索用时 109 毫秒
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利用时域有限差分方法对二维三角介质柱光子晶体的传输特性进行了研究,计算了不同晶格、同一晶格柱体截面面积不同、放置方位角不同、入射波入射方向不同时光子晶体的传输特性。结果表明:光子禁带的宽度与中心频率和晶格结构有很大关系,三角晶格更易形成平坦光子禁带,柱体截面面积大,则形成的禁带较宽,在其他因素相同的条件下柱体放置的方位角在一定范围内对光子禁带有重要影响;对不同入射方向时光子晶体的传输特性的研究结果表明,在低频范围内,入射角对禁带宽度和中心频率没有任何影响,在高频段,透射率随入射角变大而降低。研究结果为实验上制作三角柱光子晶体器件提供了重要的理论依据。 相似文献
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采用平面波展开法数值计算了空气背景中由圆形、正六边形和正方形介质柱构造的二维三角晶格光子晶体禁带结构,并研究了介质方柱旋转角度、介质折射率和填充比对完全光子禁带宽度的影响.结果表明,在低频区,介质方柱旋转17°时,出现最大完全光子禁带,且最大禁带宽度随介质折射率的变化较为稳定.在高频区,介质方柱旋转30°时,完全光子禁带宽度最大;且介质材料折射率n=2.2时即出现完全光子禁带,n=2.6时,完全光子禁带达到最大. 相似文献
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基于平面波展开法,设计了二维正方晶格和三角晶格光子晶体缺陷结构,数值模拟了TE模、TM模式的光子晶体禁带特性,计算了二维三角晶格光子晶体缺陷结构的模式分布。结果表明,光子晶体缺陷结构能够形成很好的禁带特性和模式结构,研究结论为光子晶体波导器件的开发提供参考。 相似文献
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利用平面波展开法针对三角晶格二维光子晶体的禁带结构进行了数值模拟,研究了不同浓度的NaCl溶液和酒精溶液对光子带隙的影响。选用砷化镓为三角晶格光子晶体的背景材料,这两种溶液分别为三角晶格二维光子晶体的空气孔介质材料。当不同浓度和不同折射率的NaCl溶液和酒精溶液注入光子晶体中,TE模式不出现带隙,而TM模式出现宽度不同的五种带隙,为方便选取了最大禁带宽度为参考数据。 相似文献
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采用平面波展开法分别模拟了空气背景下由介质圆柱和方柱构造的二维Archimedes(4,82)复式晶格光子晶体的能带结构,讨论了介质柱形状、折射率、填充比和旋转对称性等因素对完全光子禁带的影响.研究发现,当折射率在2.60到5.40之间时,介质圆柱和方柱构造的二维Archimedes(4,82)复式晶格光子晶体都出现了完全光子禁带.随着折射率的增大,最大完全禁带宽度并非随之增大而是存在峰值,介质圆柱型晶格在折射率为2.80时出现峰值;介质方柱型晶格在折射率为2.80和4.40两处出现峰值,且旋转介质方柱能够明显增大禁带宽度,同时存在最佳旋转角度.分析结果表明,在最大完全禁带处,折射率、填充比以及旋转角度等因素的变化对禁带特性的影响很小. 相似文献
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Kurt H Hao R Chen Y Feng J Blair J Gaillot DP Summers C Citrin DS Zhou Z 《Optics letters》2008,33(14):1614-1616
We present the design of realistic annular photonic-crystal (APC) structures of finite thickness aiming to obtain a complete photonic bandgap (PBG). The APC is composed of dielectric rods and circular air holes in a triangular lattice such that each rod is centered within each hole. The optical and geometrical values of the structure are studied, and the interplay between various design parameters is highlighted. The coupled role of the inner-dielectric-rod radius, material types, and slab thickness is investigated. It is shown that the slab thickness is vital to obtain a complete photonic bandgap below the light line, and the specific value of the inner-dielectric-rod radius to sustain the maximum PBG if the hole radius is fixed at proper value is found. 相似文献
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Y. Li C. Wang X. Lü M. Hu Y. Chen B. Liu L. Chai 《Applied physics. B, Lasers and optics》2007,86(2):235-242
Photonic crystal fibers (PCFs) can guide light by the photonic bandgap (PBG) effect created by the periodically arranged air
holes in the cladding. In this paper, the bandgap properties of Kagomé photonic crystal fibers (KPCFs) are investigated in
detail. First, the bandgap properties of PCFs based on the basic Kagomé lattice are analyzed and compared with the PBGs of
PCFs based on honeycomb and triangular lattices. We highlight the similarities between KPCFs and honeycomb PCFs in their PBGs,
both having air-guiding regions only at very large air filling fractions (AIFs), whereas the PBGs of triangular PCFs can have
large air-guiding regions at smaller AIFs due to the difference in the gap structure. In the second half of this paper, we
show how the PBGs of KPCFs can be modified by introducing an extra air hole into the vacant space of the original lattice.
In particular, KPCFs with medium-sized air holes can be designed to guide air by introducing extra air holes of a larger size.
The air-guiding regions of KPCFs with very large air holes can also be greatly extended by the extra air holes. These air-guiding
regions occur at higher normalized frequencies, resulting in larger air hole pitches favorable for fabrication.
PACS 42.70.Qs; 42.25.Bs; 42.81.Qb 相似文献
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《Solid State Communications》2006,137(1-2):74-77
A two-dimensional photonic crystal heterostructure with a large complete photonic bandgap is presented. It consists of two photonic crystals, whose dielectric configurations are reverse, with triangular lattice of circular columns. The structure retains the ease of fabrication while increasing the maximum quality factor of the gap 2–3 times after optimization. Photonic bandgap properties are calculated using a plane-wave method and the transmission spectra are obtained. 相似文献
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Effects of orientation and shape of holes on the band gaps in water waves over periodically drilled bottoms 下载免费PDF全文
The complete band gaps (CBGs) of shallow water waves
propagating over bottoms with periodically drilled holes are
investigated numerically by the plane wave expansion method. Four
different patterns are considered, containing triangular, square,
hexagonal and circular cross-sectioned holes arranged into
triangular lattices. Results show that the width of CBGs can be
changed by adjusting the orientation of noncircular holes and the
effect of hole shape on the width of the maximal CBGs is discussed. 相似文献
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In this Letter we propose a novel (to our knowledge) porous-core honeycomb bandgap design. The holes of the porous core are the same size as the holes in the surrounding cladding, thereby giving the proposed fiber important manufacturing benefits. The fiber is shown to have a 0.35-THz-wide fundamental bandgap centered at 1.05?THz. The calculated minimum loss of the fiber is 0.25?dB/cm. 相似文献
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Taishi Sumita Tetsuya Yamaki Shunya Yamamoto Atsumi Miyashita 《Applied Surface Science》2002,200(1-4):21-26
Surface charge separation behavior of photo-generated carriers in highly oriented TiO2 anatase and rutile films was investigated using a technique in which the transient surface charge is observed by laser pulse irradiation without metal contacts and an externally applied field. According to the measurements, the quantum efficiency of photo-generated holes transported toward the surface was determined as a function of incident laser energy. The photo-generated holes in anatase can be transported toward the surface for irradiation at the photon energy of its bandgap. The holes transported toward the rutile surface, however, were generated close to the surface for irradiation at the photon energy much higher than its bandgap. 相似文献
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Wide angularly isotropic photonic bandgaps obtained from two-dimensional photonic crystals with Archimedean-like tilings 总被引:1,自引:0,他引:1
We present a theoretical study of new two-dimensional photonic crystals based on Archimedean-like tilings. Three structures are considered: a square lattice with a 4-atom unit cell and triangular lattices with 7- and 13-atom unit cells. A 12-fold local rotational symmetry is obtained for the triangular lattices and is approached for the square lattice. Wide photonic bandgaps can then be achieved, with very weak bandwidth dependence (~1%) on the wave-propagation direction. The complete bandgap frequency is shown to depend on the atomic bond length and not on the crystal period. This new class of periodic photonic crystals is a simple and attractive alternative to photonic quasi crystals. 相似文献