光量子阱结构束缚态对介电常数和厚度的响应

为了考察影响光量子阱束缚态的因素,采用传输矩阵法计算了不同介电常数和介质厚度对光量子阱结构的传输特性,发现光量子阱结构的束缚态的频率随介电常数和厚度变化而变化。通过微小地改变阱区和垒区介质的介电常数和厚度可改变束缚态的频率,且阱区和垒区介质的介电常数和厚度的变化与束缚态频率的变化都呈良好的线性关系,阱区介质的介电常数和厚度的变化对束缚态频率的变化大于垒区。结果表明,光子的束缚效应将导致频率的量子化。此结果为设计所需要的束缚态频率光量子阱结构提供了理论依据。     

复介电光量子阱结构:多通道滤波和高效光放大

用传输矩阵法计算了光量子阱结构的传输特性.计算结果表明:光子的束缚效应将导致频率的最了化,光子禁带中出现多个束缚态,且束缚态的个数与阱光子晶体的周期数相等,为设计所需要的多通道滤波器提供了理论依据.当在光量子阱结构的一种介质中掺人激活介质使得介质的介电常数具有一个负虚部,各束缚态都出现了较强的增益,从而形成高效的多通道放大器.随着介电常量负虚部绝对值的增加,各透射增益先增加后减少,中间存在一极值点,但各束缚态出现透射增益极值点的虚部、最大增益的大小以及出现脱增益的虚部范围都不同.而当组成光量子阱结构的一种介质的复介电虚部为止时,表现为对各束缚态的吸收.这一结果为光子晶体同时获得多通道超窄带滤波器和所需放大倍数的光放大微器件提供了理论基础.     

激活杂质对光量子阱束缚态的影响

引入复介电常数并利用传输矩阵法研究了激活杂质对光量子阱束缚态的影响.计算结果表明:当在光量子阱结构的一种介质中掺入激活介质使得介质的介电常数具有一个负虚部时,束缚态出现了较强的增益,实现高效光放大.在光量子阱中的垒介质中掺入激活杂质和在阱介质中掺入激活杂质对束缚态的影响规律相似,但在阱介质中掺入激活杂质对光量子阱的放大更明显,光量子阱起放大作用时,阱介质中介电常数的负虚部较小,束缚态出现透射率的峰值也较大.但在光量子阱中掺入激活杂质时,透射波和反射波中的束缚态宽度都变化不大,且束缚态的频率也不变.这为掺激活杂质的光量子阱结构应用于光放大器提供了理论依据.     

一维单势垒光量子阱中多通道特性分析

用传输矩阵法研究了形式为(AB)m(CD)n(BA)m的一维单势垒光量子阱结构的隧穿通道特性。研究结果表明,阱层周期数决定了光量子阱中隧穿通道个数。垒层周期数对通道位置、个数、间距无调控作用。晶格常数变大,能明显调节隧穿通道的位置及间距,且晶格常数越小,通道越精细。入射角变化可对通道的位置、间距进行微调,且角度越大,通道越精细。该特性可为设计可调多通道光学滤波器等量子光学器件提供指导。     

实现高效光滤波与放大功能的掺激活杂质光量子阱

通过传输矩阵法理论,研究激活杂质对双重势垒光量子阱滤波器特性的影响,结果表明:介质未掺激活杂质时,双重势垒光量子阱滤波器品质随垒层周期数的增大而提高,同时滤波通道的频率发生位移;内、外垒层或阱层介质分别掺激活杂质时,各共振隧穿模出现高倍光放大现象,且各共振隧穿模的频率位置恒定;随激活介质介电虚部大小的增大光量子阱滤波器品质迅速提高,特别是阱层介质掺杂时品质提高尤为明显,高达8.010104倍;利用双重势垒光量子阱的阱层或内、外垒层掺杂激活特性,可实现高品质光滤波、光信号放大功能,且为光量子阱的实际设计与应用提供积极指导。     

一维光量子阱滤波性能的研究

利用传输矩阵理论研究了形式为(AB)m(ABBA)n(BA)m一维对称光量子阱结构的传输特性.研究结果表明:一维光量子阱垒区和阱区不同周期数、介质A和介质B不同高低折射率比都会对该结构的禁带宽度和透射率影响很大,而选取不同的中心波长又会影响光量子阱的带隙位置.为了制作更精密的光学开关、光滤波器等光学器件,综合考虑这些因素的影响是十分必要的.     

双周期光量子阱中的共振透射谱

用传输矩阵法研究了一维双周期光量子阱中的共振透射谱,揭示了光子隧穿双周期光量子阱时共振透射谱线的规律.研究发现,该结构拓宽了光子禁带区域,同时禁带中出现了多个共振透射谱,光子晶体的垒区通带频率范围内共振透射谱线的个数主要与光量子阱中垒区的周期数有关,而光子晶体的阱区通带频率范围内共振透射谱线的个数主要与光量子阱中阱区的周期数有关.同时也发现当双周期光量子阱结构的周期数为N时,适当调节垒区和阱区的周期数,可使每个共振透射谱分裂为N-1条,且各分裂谱线互不交叠,这样在有限的禁带区域可以成倍增加光子束缚态,使信道密度增大,能有效地优化光波带宽的使用,有望在光通信超密集波分复用和光学精密测量中获得广泛应用.     

介质折射率对光子晶体量子阱滤波性能的调制

为设计高品质的光学滤波器件,利用传输矩阵法理论,通过数值计算模拟的方法,研究垒、阱层介质折射率对光量子阱滤波带宽的调制机制,结果表明,光量子阱滤波带宽对垒、阱层介质折射率的响应相当灵敏:垒层高折射率介质的折射率越大,光量子阱的滤波带宽越窄;垒、阱层介质的折射率和的比值越大,光量子阱的滤波带宽越窄。光量子阱滤波带宽对介质折射率的响应机制,为提高光子晶体光学滤波器件的品质、性能提供方法依据,同时对光量子阱的理论研究也具有积极的指导意义。     

含双负介质一维光子晶体量子阱的透射谱研究

用传输矩阵法研究一维光子晶体(AB)m(BACAB)n(BA)m的透射谱,研究发现：在双正介质和含双负介质情况下,归一化频率1.0ω0/ω处光子晶体(BACAB)n的能带皆处于光子晶体(AB)m(BA)m的禁带中,均构成以1.0ω0/ω处为对称中心的光量子阱结构。光量子阱透射谱出现对称分布的共振透射峰,呈现明显的量子化效应,透射峰数目和位置可由n调节控制,且双正和含双负光量子阱结构的透射谱结构相同,但后者的透射峰带宽、间距比前者大。该特性可用于设计微波范围内的可调性多通道滤波器和光开关等。     

实现多通道光滤波与放大功能的光子晶体量子阱

为设计高效光滤波、光放大、光衰减和光开关等新型量子光学器件,用传输矩阵法理论研究了一维光子晶体（AB）m（AABAABAABAA）n（BA）m的光传输特性,结果发现:在实介电常量或复介电常量情况下,光子晶体均构成光量子阱结构,并呈现明显的量子化效应,实介电和复介电常量量子阱的透射谱结构与特点相同,透射峰数目和频率位置均与周期数n 密切相关;当折射率nB为含负虚部的复介电常量时,光量子阱的共振透射峰出现不同程度的透射增益、放大现象,增益倍数最高达103 数量级,同时共振透射峰频率处出现很强的受激辐射,辐射极强达到104数量级;当n3 时,随n的增加量子阱透射增益倍数呈现下降趋势,共振透射峰频率处的受激辐射也随之下降;当nB为含正虚部的复介电常量时,共振透射峰则出现明显地透射衰减现象。这些特性为实验制备工作提供理论依据和指导。     

Influence of two-dimensional magnetic photonic quantum wells on resonant tunneling spectral character

The non-magnetic material closed photonic quantum well (PQW) and magnetic material PQW structures based on the non-magnetic material open PQW are proposed. The transmission spectra and the field distributions of these three PQW structures are calculated by finite-difference time-domain method, the quantized energy states are researched, and the feasibility of enhancing spectral intensity significantly by selfstructure is disclosed. It is found that the optical transmittance of the magnetic PQW is close to 1, and the energy loss is less compared to non-magnetic PQW.Compared with the closed PQW structures, the device's volume can be reduced, the degree of free regulation of the energy band project can be increased, and more photon bound states can be obtained. The results show that the open PQW is the traveling wave well, and its capability of capturing photons is weak. However, the closed PQW and the magnetic PQW are standing wavewells. Their capabilities for capturing photons are strong,while the light field gradient of the material PQW is bigger.     

Ferroelectric ceramic electrooptic materials and devices

Thin polished plates of hot-pressed rhombohedral lead zirconate-lead titanate ceramics possess one of two types of electro-optic properties depending on the nominal grain diameter. In poled coarse-grained ceramics the electrooptic effect of importance for devices is the dependence of the light scattering properties on the orientation of the ceramic polar axis (electrical poling direction). The light scattering properties are essentially independent of the magnitude of electrical poling (ferroelectric remanence state). Poled fine-grained ceramics are birefringent, and their light transmission characteristics are similar to those of optically uniaxial crystals. These materials exhibit orthotropic symmetry with respect to the optic axis, which coincides with the ceramic polar axis. The fine-grained ceramic electrooptic effect of primary importance for devices is the dependence of the effective birefringence on the magnitude of electrical poling as well as on the intensity of the applied biasing electric field. Retardation of a ceramic plate can be varied incrementally by partial switching or continuously by application of a nonswitching bias field. Both coarse- and fine-grained ceramics have the property that localized areas as small as 25 µ by 25 µ can be poled or switched independently without affecting the light transmission characteristics of the surrounding area. The locally switched areas are stable with time, but they can be "erased" by switching them back to their original orientation. Each locally switched area can function as a light shutter, valve, or spectral filter depending on the ceramic material, the switching mode, and the characteristics of the incident light.     

钒酸钇Wollaston棱镜分束特性分析

为了解钒酸钇Wollaston棱镜的分束特性,通过棱镜中的光路分析,得到光束正入射时o光光束和e光光束的分束特性公式,并用MATLAB软件拟合得到棱镜的分束特性关于入射光波长和结构角的变化关系曲线。结果表明,对于一定结构角的棱镜,其分束角具有明显的色散特性,波长越短,分束角越大,且变化也越快,在红外光谱范围,波长对棱镜分束角的影响减小,其分束角趋于稳定;分束角的对称性受波长变化的影响较小,应用中可以忽略。棱镜的结构角与入射光波长对棱镜的透射比均有影响,当棱镜的结构角一定时,透射比随入射光的波长呈振荡性变化,且o光透射比的光谱效应更为明显。该研究可以为棱镜的设计制作和实际使用提供有价值的参考。     

蜂窝夹层结构传输性能随入射角变化规律研究*

使用高Q 谐振腔材料介电性能测试系统,对不同入射角下、不同格孔边长的NOMEX 纸蜂窝材料介电性能进行了测试。结果表明,相同格孔边长的情况下,NOMEX 纸蜂窝材料损耗角正切值随入射角的增大而增大,且小格孔蜂窝受入射角影响较大。为明确蜂窝材料介电性能的这种特性对夹层结构性能影响,设计并加工了一块5 层夹层结构等效平板,通过设计仿真结果和试验结果对比分析,并结合测试误差分析,明确了蜂窝介电性能随入射角变化对夹层结构传输性能的影响及其原因。     

Coherently Controlled Multifunctional Active Optical Filters

In this paper, we propose multifunctional active optical filters using coherent nonlinear effects and quantum interference in quantum-well structures. Based on the application demand, in the absence of a control laser field, these filters can be either completely opaque or transparent. However, in the presence of such a control laser, the filter structure is activated, allowing transmission of a single frequency. We show that the amplitude and linewidth of these filters can be optically controlled, demonstrating various functionalities and performances including attenuation, amplification, and switching processes. We also show that, with proper design of such active filters, one can tune the wavelength of the filtered signal by varying the intensity of the control field.     

晶格常数对光子晶体量子阱透射谱的影响

为设计高品质光学滤波器、光开关等量子光学器件,用传输矩阵法理论研究晶格常数对一维光量子阱（AB）5（CD）2（BA）5透射谱的影响,结果发现:当A、B介质层的晶格常数偶数倍增加时,禁带中心频率处的窄透射峰变成宽透射带,透射带两侧对称分布着2条透射率为100%的窄透射峰;当A介质层的晶格常数奇数倍增加时,禁带中心频率处出现透射率为100%单条窄透射峰;当B介质层的晶格常数奇数倍增加,或D介质层的晶格常数按整数倍增加时,禁带中心频率处恒定出现3条透射率为100%的窄透射峰,且三者之间距离随着B、D介质层晶格常数的增大而逐步向禁带中心靠拢;当D介质层晶格常数按整数增加时,不仅禁带中心频率处恒定出现3条透射率为100%的窄带透射峰,同时两侧对称出现与晶格常数倍数密切相关的双透射峰结构,且双透射峰的透射率随晶格常数倍数增大而增高。这些特性可实现可调通道光滤波和光开关功能,并为实验制备工作提供理论指导。     

Analysis of an Improved Split-Step Algorithm for Simulating Optical Transmission Systems

The standard Split-Step algorithm for calculating the signal transmission through optical fibres is significantly accelerated without relevant loss of accuracy by applying IIR filters as well as Fourier transformations for the linear operator. Depending on the system topology, high speed-up factors can be achieved by switching back and forth between time and frequency domain algorithms for the linear operator. Two different IIR filters are applied for calculating linear and parabolic dispersion. The efficiency of this algorithm in combination with an innovative step-size allocation method is evaluated.     

腔体为单轴晶体的F-P滤光片光学性质仿真研究

为了计算腔体为单轴晶体的F-P滤光片的光学性质,采用理论分析的方法,对垂直入射到光轴在入射面内的单层单轴晶体薄膜的寻常光与非寻常光在两界面处的电磁场量的边界条件和薄膜两界面处电场量的相位关系进行了分析,得到了单层晶体薄膜反射率与透射率的计算方法,并将其应用于腔体为单轴晶体的F-P滤光片光学特性的仿真,取得了滤光片透射率随光轴方向变化的数据。结果表明,光轴旋转角对F-P滤光片的透射峰有明显影响。     

Smart windows switch on the light

Optical switching devices for regulating incident solar energy that can replace traditional windows in buildings, vehicles, and aircraft are discussed. The chromogenic material in these smart windows exhibits a large change in optical properties with variation in applied electrical field, charge, light intensity, spectral composition, or temperature. The optical change transforms the material from a highly transmitting state to a partly reflecting (or absorbing) state over all or part of the visible and solar spectra. The optical switching can be activated electrically or nonelectrically. Electrically activated types, including electrochromic, liquid-crystal, and dispersed-particle (electrophoretic) devices, as well as devices based on reversible electrodeposition, and nonelectrically activated types, including devices based on photochromic and thermochromic materials, are described