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1.
As one of the most attractive non-radiative power transfer mechanisms without cables,efficient magnetic resonance wireless power transfer(WPT)in the near field has been extensively developed in recent years,and promoted a variety of practical applications,such as mobile phones,medical implant devices and electric vehicles.However,the physical mechanism behind some key limitations of the resonance WPT,such as frequency splitting and size-dependent efficiency,is not very clear under the widely used circuit model.Here,we review the recently developed efficient and stable resonance WPT based on non-Hermitian physics,which starts from a completely different avenue(utilizing loss and gain)to introduce novel functionalities to the resonance WPT.From the perspective of non-Hermitian photonics,the coherent and incoherent effects compete and coexist in the WPT system,and the weak stable of energy transfer mainly comes from the broken phase associated with the phase transition of parity-time symmetry.Based on this basic physical framework,some optimization schemes are proposed,including using nonlinear effect,using bound states in the continuum,or resorting to the system with high-order parity-time symmetry.Moreover,the combination of non-Hermitian physics and topological photonics in multi-coil system also provides a versatile platform for long-range robust WPT with topological protection.Therefore,the non-Hermitian physics can not only exactly predict the main results of current WPT systems,but also provide new ways to solve the difficulties of previous designs.  相似文献   
2.
理论研究表明,在基于光子晶体的耦合腔波导中,杂质带的色散性质取决于相邻缺陷间局域电磁场的特性,而非缺陷间距离的大小.在第一布里渊区中出现的杂质带的反常色散实际上是能带折叠的结果.通过计算结构的有效折射率,证实了杂质带色散是正常色散. 关键词: 光子晶体 反常色散 耦合腔 杂质带  相似文献   
3.
张振清  路海  王少华  魏泽勇  江海涛  李云辉 《物理学报》2015,64(11):114202-114202
本文对具有类EIR色散特性的平面金属等离激元美特材料(planar plasmonic metamaterials, PPM)对光学Tamm态及相关激射行为的增强作用进行了研究. 我们首先运用传输矩阵方法分析了利用PPM结构的色散来增强光学Tamm态对应模式电磁局域密度的可能性. 其次, 我们将具有类EIR特性的PPM与一维光子晶体(photonic crystal, PC)合在一起设计了一种平面等离激元美特材料-光子晶体(PPM-PC)异质结构. 研究发现, 通过在电磁局域密度最高的PPM结构中(或附近)加入增益介质, 可观察到比通常光学Tamm态更强的激射增强效应及更明显的单色性响应. 这些特性使得这种PPM-PC结构有望被应用于低阈值激光器、荧光增强等方面.  相似文献   
4.
对一维掺杂光子晶体嵌入负介电常数材料和负磁导率材料中缺陷模的透射性质进行了研究.利用转移矩阵方法,分别计算了负介电常数材料和负磁导率材料的反射相位谱和一维掺杂光子晶体的透射相位谱.研究发现,在特定条件下,负介电常数材料和负磁导率材料的反射相位以及一维掺杂光子晶体的往返透射相位之和是0或者2π的整数倍.这样的研究结果表明,在满足一定的条件下,一维掺杂的光子晶体嵌入负介电常数材料和负磁导率材料中后,无论杂质的厚度多大,在光子带隙中仅出现一个缺陷模.而且,由于负介电常数材料和负磁导率材料性质的限制,单个缺陷模的品质因子会大大提高.  相似文献   
5.
A compact wavelength division multiplexer (WDM) based on a microstrip resonator containing effective zero-index media is proposed. Both numerical simulations and microwave experiments demonstrate the crosstalk suppression phenomenon in this WDM. By properly adjusting the values of lumped elements, it is convenient to achieve crosstalk suppression over 10dB. Therefore, this compact WDM is promising for applications in modern microwave communication systems for its compact device volume and unique capability to suppress the crosstalk between WDM channels.  相似文献   
6.
We study theoretically the nonlinear responses of one-dimensional photonic crystals (PCs) composed of alternating two kinds of single-negative (permittivity-negative and permeability-negative) materials embedded with a Kerrtype nonlinear defect layer. In conventional PCs, it is difficult to realize a bistable switching with both low threshold and quick response time. However, in PCs with single-negative materials, by changing the ratio of the thicknesses of the two types of layers, with the decreasing size of the structure, the switching response time is shortened and the threshold intensity decreases simultaneously.  相似文献   
7.
We show that a one-dimensional photonic crystal containing two kinds of single-negative materials can possess an omnidirectional gap whose edges are insensitive to incident angle and polarization, owing to the unusual field configuration in the structure. In contrast to an omnidirectional gap based on a photonic gap that corresponds to zero averaged refractive index, it can be made very wide by varying the ratio of the thicknesses of two media.Moreover, it is independent of polarization under special parameters. These properties may provide a mechanism to design a broadband omnidirectional reflector with fixed bandwidth.  相似文献   
8.
算术-几何平均不等式的初等证法   总被引:1,自引:0,他引:1  
算术-几何平均不等式的初等证法江海涛(马鞍山高级职业学校243001)在中学数学课本中,任意n个正实数的算术—几何平均不等式,是通过不完全归纳推理给出的,没有进行严格的证明.而学有余力的同学,经常向老师提出此不等式的证明问题.该不等式证法虽多,但常见...  相似文献   
9.
We propose a novel localized mode enhanced (LME) coupler based on quasi-one-dimensional photonic crystal microstrips, which is promising to be applied in wavelength division multiplexed microwave communication systems. Compared to the traditional microstrip coupler, the LME structure has two advantages: high efficiency and frequency selectivity. Even in a relatively far coupling distance, this structure can still achieve a high efficiency about 50%. The frequency selectivity can be realized by simply tuning the distance between two transmission lines.  相似文献   
10.
江海涛  李云辉  李宏强  朱荣林  张冶文  陈鸿 《物理》2003,32(12):799-803
文章以高方向性天线及光子晶体微带传输线为例,综述了光子晶体在微波技术中的研究进展.将光子晶体与传统的微波技术相结合,可以设计并制作许多小型、高效的新型微波器件.这类新型光子晶体材料在微波通讯中有着广阔的应用前景。  相似文献   
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