单负材料组成一维光子晶体双量子阱结构的共振模

通过传输矩阵方法, 计算模拟了两种单负材料组成一维光子晶体双量子阱结构的透射谱. 研究发现: 由于双量子阱结构双阱之间的相互耦合作用, 共振模发生双重劈裂, 共振峰之间的距离可以通过调节双阱之间的耦合强度控制, 共振模的品质因子可以通过调节外部障碍光子晶体的周期数控制. 并且, 共振模受入射角和光偏振模式的影响都比较小, 适合全方向滤波. 当考虑两种单负材料不同损耗的影响时, 研究结果表明, 电损耗对低频处的共振模影响大, 而磁损耗对高频和低频处的共振模影响都比较大.     

Resonant modes and inter-well coupling in photonic quantum well with negative index materials

The transfer matrix method was used to study the resonant modes in photonic quantum well by stacking different photonic crystals consisting of positive index materials and negative index materials. The eigenfrequency equation for the resonant modes is derived. It is found that these resonant modes are omnidirectional, and the number of resonant modes is equal to the period number of photonic quantum wells. Moreover, the resonant modes become N-fold splitting in the N photonic quantum wells. The splitting intervals increase with the deceasing of photonic barrier thickness due to the coupling among the wells.     

Resonant modes in photonic multiple quantum well structures with single-negative materials

A type of photonic multiple quantum well (PMQWs) structure made of two different photonic crystals (PCs) with two kinds of single-negative materials is investigated. It is demonstrated by transfer matrix method that omnidirectional resonance modes are generated. The number of the resonance modes can be controlled by adjusting the periodic structure of the constituents. The resonance tunneling modes are weak dependence on incident angle and the scaling of the barrier photonic crystals. When the losses are taken into account, the effects of the losses coming from ENG media and MNG media on the resonance modes are striking difference.     

含特异材料的光量子阱频率特性研究

基于传输线加载集总元件的方法制备光量子阱. 对阱内物质为光子晶体和左手材料两种情况下的传输特性进行比对. 结果表明局域模个数与阱内物质的周期数相同; 左手材料情况下光量子阱具有尺度小、 便于调节的优点.实验结果与理论结果相符合.     

基于含单负材料光量子阱结构的全向多通道滤波器

分析了含单负材料的光量子阱结构中的振荡透射模的性质.用两种单负（负介电常量或负磁导率）材料交替周期堆叠形成的两个光子晶体构造了一维光量子阱结构,该结构中仅其中一个光子晶体含有零有效位相带隙.数值计算结果发现,在零有效位相带隙内存在振荡透射模.通过改变井区域光子晶体内单负材料层的厚度及周期数,振荡透射模的数目、频率及频率间隔均可调节.振荡透射模对入射角度的依赖均很弱;随着入射角度的改变,缺陷模频率的相对改变量保持在0.02以下.该研究结果可用于设计多通道全向滤波器.     

Bragg polaritons: strong coupling and amplification in an unfolded microcavity

Periodic incorporation of quantum wells inside a one-dimensional Bragg structure is shown to enhance coherent coupling of excitons to the electromagnetic Bloch waves. We demonstrate strong coupling of quantum well excitons to photonic crystal Bragg modes at the edge of the photonic band gap, which gives rise to mixed Bragg polariton eigenstates. The resulting Bragg polariton branches are in good agreement with the theory and allow demonstration of Bragg polariton parametric amplification.     

光子晶体双量子阱的共振隧穿

采用R矩阵法研究了二维光子晶体双量子阱的共振隧穿特性.研究发现:光子晶体双量子阱的共振频率可以通过调节双阱的耦合强度来控制;对称双量子阱中,共振峰发生双劈裂;不对称双量子阱,共振劈裂消失.但是,由改变左手介质和右手介质在双阱中的排列顺序产生的阱介质不对称阱的共振劈裂消失与阱宽不对称的双阱产生的共振劈裂消失不一样.进一步对一维光子晶体量子阱分析后发现,前者是由光在左右手介质中传播的能流方向相反产生干涉相消而引起;后者是由阱宽不同,阱的本征模不一样而引起. 关键词： 光子晶体 双量子阱 R矩阵')" href="#">R矩阵 左手介质     

偶极子位置及偏振对激发光子晶体H1微腔的影响

光子晶体微腔和量子点的集成是实现量子信息处理非常具有潜力的平台之一,利用微腔和量子点的耦合可以制备纠缠光子对,实现对量子态的操控.因为光子晶体微腔具有品质因子高、模场体积小等优点,可以极大地增强光与物质之间的相互作用,从而易于实现量子态在不同物理体系之间的转换.通过单量子点和光子晶体H1微腔的耦合可以产生纠缠光子对,因为H1微腔具有简并的、模式偏振正交的基态模式.通常微腔模式的激发随着量子点在微腔中的位置变化而改变,本文用时域有限差分方法研究了偶极子光源的位置及偏振对激发光子晶体H1微腔模式的影响.结果表明:通过改变偶极子光源位置可以选择性地激发H1微腔简并模式中的一个;具有某一偏振的偶极子光源只能激发相应偏振的微腔模式;模式激发强度的大小也是由偶极子光源在微腔中的位置决定的.鉴于目前量子点在微腔中的位置尚不能精确控制,所以微腔模式受激发光源位置的影响的研究具有重要意义.     

亚波长周期性各向异性金属薄膜的等离子体共振特性

 基于各向异性模型,运用全矢量的3维时域有限差分法（FDTD）,研究了在外磁场作用下,亚波长周期性各向异性金属薄膜的表面等离子体共振机制和特性,即由周期性穿孔形成的局域波导共振和由周期性结构引起的光子晶体共振效应。研究发现:当薄膜厚度一定时,两种等离子体共振模式都会随着外磁场的增大而向短波方向移动;而当外磁场一定、薄膜变厚时,周期结构因素引起的共振传输峰向长波方向转移,波导共振传输峰向短波方向转移;通过调控外加磁场的大小或方向可控制光通过金属薄膜的增强传输效应。     

二维光量子阱共振隧穿光谱特性的改善

用时域有限差分法研究了光子晶体量子阱中的量子化能态.研究发现,开腔与闭腔光量子阱结构共振透射峰的数目相同,位置几乎不变,但闭腔光量子阱出射光强更强,透射率更大,频率选择性更好,品质因子Q值更高.同时计算了开腔和闭腔光量子阱光场分布,结果表明,开腔光量子阱为行波阱,闭腔光量子阱为驻波阱,充分证实了闭腔光量子阱更能束缚光场的设想,对其作用机理进行了探讨.     

不同晶格常数光子晶体构成的光量子阱中的共振模

用基于平面波的传输矩阵法分析由具有不同晶格常数的光子晶体材料构成的光量子阱结构中的共振模，发现湮没于垒层的阱层能带分离成共振模，且共振模的数目随阱层的厚度变化而改变。提出一种新型的非对称量子阱结构模型，由2块晶格常数不同的光子晶体材料和夹在光子晶体材料中间作为阱层的均匀介电材料构成，并对其中的共振模进行了分析。指出当阱层厚度达到构成垒层的光子晶体晶格常数的一半时出现一个共振模，若继续小量增加阱层厚度将使共振模频率出现红移。最后给出一种基于平面波的传输矩阵法，且对于不同晶格常数的光子晶体量子阱结构均有效的数值模拟方法，可用于研究由三维光子晶体材料或者色散材料组成的光子晶体量子阱结构。     

Resonant modes in quantum well structure of photonic crystals with different lattice constants

The resonant modes in a quantum well (QW) structure composed of three slabs of two dimensional (2D) photonic crystals with different lattice constants are analyzed with plane-wave-based transfer matrix method (TMM). It is found that the energy band of the well slab submerged into the band gap of barrier slab is discretized into quantized modes and the number of the resonant modes changes with the well slab thickness. A model structure of asymmetrical photonic QW consisting of two slabs of 2D photonic crystals with different lattice constants and one uniform dielectric slab in between is proposed and the resonant modes in it are investigated with the same method. A useful numerical simulation method for theoretical discussion as well as for practical application about photonic QW structure of photonic crystals with different lattice constants is proposed.     

渐变折射率光量子阱对束缚态能级的调整

在对称的均匀电介质材料光子晶体体系中插入另一折射率渐变的光子晶体可构成光量子阱结构.利用时域有限差分法计算了不同折射率分布光量子阱结构的传输谱.研究表明：束缚态是对处于垒光子晶体禁带中的阱光子晶体导通带的离散化,束缚态能级个数等于阱光子晶体结构单元的重复周期数；以渐变方式调整阱区折射率分布,可在特定频率范围内得到新的互不交叠的束缚态.这样在有限的禁带区域可以成倍增加光子束缚态而无需增大光量子阱结构的尺寸,使信道密度最大化、光波有效带宽的使用最优化.这种量子阱结构可用于制作超窄带滤波器和多通道窄带滤波器,有望在光通信超密集波分复用和光学精密测量技术中获得广泛应用. 关键词： 光量子阱 光子束缚态 渐变折射率 光子晶体     

Transmission spectra through photonic double quantum well system

By means of the modal expansion method with an R-matrix propagation algorithm, effects of the coupling between resonance photonic states on the resonance tunneling through a double quantum well structure are investigated. We examine the effects on the transmission spectra due to variation of the second well width and middle barrier thickness. Drastic change of the tunneling spectra is found and analyzed when the wells are filled with left-hand media.     

半导体纳米材料和物理

半导体纳米材料是纳米材料的一个重要组成部分，纳米结构的电子和光子器件将成为下一代微电子和光电子器件的核心。文章介绍了半导体纳米材料研究的新进展，包括四个方面：半导体自组织生长量子点，纳米晶体，微腔光子晶体和纳米结构中的自旋电子学。本世纪开始的半导体纳米材料的研究是上世纪半导体超晶格量子阱研究的延续，同时又开辟了一些新的领域，如：单电子的电子学、单光子的光子学，微腔和光子晶体，稀磁半导体和自旋电子的相干输运等，这些研究将为研制在新原理基础上的新器件和实现量子计算、量子通信打下基础。     

Control of absorption spectrum of a one-dimensional resonant photonic crystal

The crystal under consideration is a layered structure consisting of alternating layers of two materials, one of which is a resonantly absorbing gas. It is shown that the combination of the dispersion of an atomic gas with the dispersion of a photonic-bandgap structures allows one to efficiently control the transmission spectra of s- and p-polarized modes in these combined systems. It is found that the spectrum is highly sensitive to the position of the gas resonance frequency with respect to the bandgap edge and to a change in the gas pressure. The transmission, reflection, and absorption spectra of the resonant photonic crystal are studied at an angle of incidence equal to the Brewster angle of a seed photonic crystal. Possible applications of the found particular features of the dispersion of resonant photonic crystals are discussed.     

Two mode photon bunching effect as witness of quantum criticality in circuit QED

We suggest a scheme to probe critical phenomena at a quantum phase transition (QPT) using the quantum correlation of two photonic modes simultaneously coupled to a critical system. As an experimentally accessible physical implementation, a circuit QED system is formed by a capacitively coupled Josephson junction qubit array interacting with one superconducting transmission line resonator (TLR). It realizes an Ising chain in the transverse field (ICTF) which interacts with the two magnetic modes propagating in the TLR. We demonstrate that in the vicinity of criticality the originally independent fields tend to display photon bunching effects due to their interaction with the ICTF. Thus, the occurrence of the QPT is reflected by the quantum characteristics of the photonic fields.     

Exciton-polariton absorption in periodic and disordered quantum-well chains

The exciton-polariton transfer and absorption in regular and disordered structures with a finite number of quantum wells are studied theoretically. The transfer matrix method is invoked in the exciton resonance region to calculate the reflectivity, transmissivity, and absorptivity spectra, as well as the integrated absorptivity as a function of the γ/Γ₀ ratio of the parameters of nonradiative and radiative damping of quasi-two-dimensional excitons. It is shown that the integrated absorptivity as a function of γ (temperature) follows a universal pattern, more specifically, it increases monotonically from zero at γ = 0 to saturate at γ/Γ₀ ? 1. Because the exciton-polariton absorption being single mode, the integrated absorptivity in Bragg quantum-well structures is substantially lower than that in short-period structures, in which absorption involves the whole spectral multitude of modes. The intrawell disorder associated with fluctuations in the frequencies of exciton excitation in quantum wells enhances the integrated absorptivity to the level typical of light absorption with no resonance among excitons of different quantum wells. The interwell disorder originating from fluctuations in quantum-well separation likewise leads to an increase in the integrated absorptivity.     

Angular correlation of photons emitted from an excited quantum well

We study the angular correlation of single photons emitted from excited semiconductor quantum wells. The considered physical system is described in terms of two subsystems, the electronic part constituting the bath and the photonic part constituting the bathed subsystem, both being coupled by the light-matter interaction. From the master equations describing the coarse-grained Markovian evolution of the photonic subsystem, we derive the corresponding equations of motion for the photonic angular correlation functions. These equations are solved in the stationary, low-density limit. Experimentally, the angular correlations can be assessed by studying the interference of light emitted in different directions. In agreement with recent experimental results, we find that for ordered quantum wells angular correlations exist only in emission directions for which the projections of the photon momenta onto the plane of the quantum well are equal. This feature is a direct consequence of the Bloch character of the electronic states in an ordered quantum well. Thus the experimental study of the angular correlations of emitted photons may provide an interesting diagnostic tool to reveal the presence of disorder in semiconductor heterostructures and to characterize its influence on the electronic states near the band edges.     

含Kerr非线性的一维光子晶体中的类孤子

研究了含Kerr非线性的一维光子晶体中的类孤子。计算了光子晶体中加入Kerr非线性材料后,类孤子和入射光强、Kerr系数以及线性势阱的关系。随着线性势阱的降低,对应于在线性带隙中开始出现类孤子本征模所需要的最小入射强度也降低,即降低了非线性阈值;尽管非线性是产生类孤子的根本原因,但非线性系数对产生类孤子及孤子环中环的影响不如线性势阱高度的影响显著。