共查询到16条相似文献,搜索用时 703 毫秒
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对于晶体光轴平行于波导界面的结构,讨论了光在金属包层对称平面单轴晶体波导(波导层是单轴晶体,两个波导界面均为金属)内的传输特性.解析地得到了这种结构下波导模式场的精确解.模式场的性质因单轴晶体的性质不同而异.对于正单轴晶体,波导的主模是横电波,任何频率的光波均可激励该模式;当频率满足一定条件时,波导内传输单模,否则,将激励起高阶模式.高阶模既非TE波,也非TM波,而是两者耦合而成的混合模.对于负单轴晶体,波导的主模是一种混合模,该模式同样可被任何频率的光波所激励;当频率满足一定条件时,波导内传输单模,否则
关键词:
平面金属波导
单轴晶体
模式场
混合模 相似文献
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利用传输矩阵法研究了单负材料一维光子晶体(AB)m(ADBDB)n(AB)mA的透射谱,发现:透射谱中出现2个共振隧穿模,其位置和间距可由周期数m或n,以及介质层厚度d调节控制。改变m,会出现2个恒定间距的共振隧穿模;改变dA,共振隧穿模间距增大,且当dA≥25mm时,间距增大加剧;改变n,共振隧穿模逐渐趋于简并,当n≥6时,两隧穿模合二为一;改变dD,两共振隧穿模亦逐渐趋于简并,当dD≥20mm时,两隧穿模亦合二为一。这些特性可为利用光子晶体设计可调性高品质单通道、双通道滤波器提供参考。 相似文献
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用传输矩阵方法研究了由两种单负材料构成的光子晶体异质结构的透射特性.结果表明,当异质结构具有零有效折射率时,由于迅衰场表面模共振耦合,在异质结构双周期光子晶体的每一个分界面上都会出现隧穿模.零有效折射率隧穿模不受入射角、电磁波偏振态、结构周期数和晶格常数标度等因素影响,并且具有零相位延迟,这一特性可用来设计零相位延迟全向多通道滤波器件.而位于中心两侧的隧穿模随入射角、结构周期数和晶格常数标度的减小都统一由中心向两侧移动.
关键词:
单负材料
异质结构
传输矩阵 相似文献
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研究了金属板上下两个表面内侧都周期性地嵌入电介质小球体系的透射和吸收性质.结果显示:对于嵌入深度很小的电介质小球,电磁波可通过隧穿效应进入到电介质小球内,并以腔体本征模式的形式存在.当嵌入深度很小时,周期排列的电介质小球会对金属表面做有效的周期性调制,使体系在特定的频率出现金属表面等离子激元.当腔体本征模式与金属表面等离子激元模式的频率相近时,它们之间的耦合将使两种电磁模式大幅度地增强,从而使上层的电介质小球内具有非常强的电磁场.这些高强度的电磁场有相当一部分可通过隧穿效应进入到下层的电介质小球内,并通过
关键词:
腔体模式
表面等离子激元
透射 相似文献
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采用Tiersten方程研究了环形ZnO薄膜谐振器中横模寄生问题, 获得了环(圆)形薄膜谐振器的横模振动方程, 求得横模位移场解和频率色散方程; 然后采用电磁学模式合成理论进行分析, 发现环形薄膜谐振器横模频率与环形电极的内外径之比a/b有关, 振动模式可由圆形薄膜谐振器横模模式合成得到, 通过控制a/b能够抑制横模模式数和调控基膜频率. 采用外差激光干涉仪和网络矢量分析仪测量并比较了同批次的圆形和环形薄膜谐振器的上电极横模振动图样和电阻抗曲线. 振动图样显示环形薄膜谐振器振动模式可由半径为a和半径为b的圆形薄膜谐振器振动模式合成, 仅存在节圆数大于0的横模振动, 等于0的横模模式被抑制; 电阻抗曲线显示当a/b为0.436时, 环形薄膜谐振器的基频(约1217 MHz)和圆形的(0, 1)模式频率相等. 测量数据验证了模式合成理论的分析结果正确性, 为薄膜谐振器的横模抑制研究提供了理论基础和新方法. 相似文献
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Vandenbem C 《Optics letters》2008,33(19):2260-2262
The study of the dependence of surface mode dispersion on the termination of multilayer stacks reveals interesting features. For stratified media with high-refractive-index contrasts, surface modes can shift across several bandgaps if the thickness of the final layer is changed. The distance to the photonic band edge influences the decay length of the mode inside the multilayer stack. In the middle of the bandgap, the electromagnetic energy is concentrated in the final layer of the crystal, while near bandgap edges the decay length extends over several periods. Additional evidence suggests that surface modes behave like guided modes that can couple with the extended Bloch modes and give rise to evanescent field profiles oscillating along several periods. 相似文献
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Long-range surface plasmon polaritons with subwavelength mode expansion in an asymmetrical system 下载免费PDF全文
Long-range surface plasmon polariton (LRSPP) modes in an
asymmetrical system, in which the thin metal film is sandwiched
between a semi-infinite substrate and a high permittivity polymer
film with a finite thickness, are theoretically calculated and
analyzed. Due to the high permittivity of the polymer film, at
proper polymer film thicknesses, the index-matching condition of the
dielectrics at both sides of the metal can be satisfied for
supporting LRSPP modes, and the electromagnetic field above the
metal can be localized well. It is found that these LRSPP modes have
both long propagation lengths and subwavelength mode expansion above
the metal at the optimal polymer film thicknesses. Furthermore, the
requirements on the refractive index and the thickness of the
polymer film to support LRSPP modes at the optimal thicknesses are
found to be not critical. 相似文献
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The propagation of an electromagnetic wave through a barrier with a periodic structure is considered. An interesting manifestation
of electromagnetic wave tunneling through a barrier with a periodic structure is revealed. Specifically, it is theoretically
and experimentally shown that, when an electromagnetic wave passes through a medium with a periodic structure in the diffraction
mode within a photonic band gap, the field in the medium is localized near its boundaries. Theoretical calculations have been
performed for a cholesteric liquid crystal layer of finite thickness and for a 1D photonic crystal. The experiment was carried
out with perfect Si single crystals in reflection from the $
(2\bar 20)$
(2\bar 20)
and $
(4\bar 40)$
(4\bar 40) planes using MoK
α X rays. 相似文献
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A. M. Zheltikov S. A. Magnitskii A. V. Tarasishin 《Journal of Experimental and Theoretical Physics》2000,90(4):600-608
Properties of an electromagnetic field localized in the defect modes of two-dimensional photonic crystals are studied. The defect-mode spectrum of these structures is calculated, electromagnetic field localization and channeling effects are analyzed, and the properties of the field inside and beyond a photonic crystal with a lattice defect are also studied. The calculations show that the electromagnetic field is localized in the defect mode of a photonic crystal in a region smaller than the wavelength. The dependence of the defect-mode spectrum on the parameters of the photonic crystal is investigated and possibilities for controlling the spectrum of defect modes are indicated. It is shown that the optical field leaving a photonic crystal possesses the properties of a evanescent wave, which means that spatial resolution substantially greater than the wavelength of the radiation can be achieved in the near field and opens up possibilities for using photonic crystals with a lattice defect in near-field optical microscopy. The possibility of externally controlling an optical field localized in the defect modes of a photonic crystals is demonstrated. 相似文献