共查询到19条相似文献,搜索用时 968 毫秒
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本文用自由空间模简化及近似表示弱导多层介质光波导的辐射模.只要辐射方向与介质界面的角度不是很小,近似程度很好.将其应用于求解光栅耦合器的辐射损耗问题,使计算公式简化,用自由空间模计算的结果与用辐射模计算的结果比较接近,也与其它近似方法进行了比较. 相似文献
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本文用自由空间模简化及近似表示弱导多层介质光波导的辐射模.只要辐射方向与介质界面的角度不是很小,近似程度很好.将其应用于求解光栅耦合器的辐射损耗问题,使计算公式简化,用自由空间模计算的结果与用辐射模计算的结果比较接近,也与其它近似方法进行了比较. 相似文献
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描述了克尔介质自锁模激光器的锁模工作原理,建立了自锁模系统光强分辨率的概念,并指出了光强分辨率对自锁模系统的锁模启动和工作稳定性起着决定性的作用,通过合理控制克尔介质自锁模激光器的腔镜失谐角,可以提高系统的光强分辨率,从而使自锁模系统易于自锁模启动并提高其自锁模工作的稳定性。 相似文献
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设计了一种用于测量V波段过模高功率毫米波源在线功率的选模耦合器。利用小孔耦合理论和微元法对菱形耦合缝隙进行了理论分析,采用两组相同的菱形耦合缝隙实现选模功能,缩短了耦合器长度,增加了工作带宽。采用数值模拟的方法对耦合器结构进行优化设计,模拟结果表明:在60 GHz频点处,TM01模耦合度约为50 dB,TM02模耦合度仅为75 dB,对TM02模的抑制度为25 dB;在500 MHz带宽内对TM02模的抑制度大于15 dB,1 GHz带宽内的抑制度大于10 dB,可满足工作于TM01模的V波段高功率毫米波测试需求。同时针对工作于高次模TM0n(n=2,3,4,)的器件设计了可抑制TM01模的耦合器,为高次模工作的高功率毫米波器件的在线功率测量和模式诊断提供了技术方案。 相似文献
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利用简洁的幺正变换得到双模压缩算符在纠缠态中表示,使用同样的方法可得到双模压缩算符在坐标和动量本征态中的表示。 相似文献
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The visibility of ghost-interference patterns is investigated firstly based on the coherent-mode representation theory. We find that the intensity correlation function can be changed from the usually two-dimensional integral representation to a new one-dimensional summation representation. During the process of analyzing the effects from the light source's properties and the transmission area of the object imaged on the imaging visibility, it is shown that by compared with the results from the integral representation, the coherent mode representation is quite useful to understand more clearly the whole process of correlated imaging. 相似文献
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曲文孝 《核聚变与等离子体物理》1996,16(2):17-23
本文从一简化的新经典MHD方程组出发,利用气球模表示及多尺度近似等方法,在q=1磁面附近的过渡层内导出了包含新经典MHD效应的内扭曲模本征方程。与从前相关工作的比较表明,新经典MHD效应对通常采用的磁流体或电阻磁流体内扭曲模本征方程,均产生十分重要的修正。 相似文献
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FAN Hong-Yi HU Li-Yun 《理论物理通讯》2009,51(4):729-742
By introducing a fictitious mode to be a counterpart mode of the system mode under review we introduce the entangled state representation <η |, which can arrange master equations of density operators ρ(t) in quantum statisticsas state-vector evolution equations due to the elegant properties of <η |. In this way many master equations (respectively describing damping oscillator, laser, phase sensitive, and phase diffusion processes with different initial density operators) can be concisely solved. Specially, for a damping process characteristic of thedecay constant κ we find that the matrix element of ρ (t) at time t in <η| representation is proportional to that of the initial ρ0 in the decayed entangled state <ηe-κt| representation, accompanying with a Gaussian damping factor. Thus we have a new insight about the nature of the dissipative process. We also set up the so-called thermo-entangled state representation of density operators, ρ=∫(d2η /π)< η | ρ> D(η), which is different from all the previous known epresentations. 相似文献
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Shiwen Yang Soon Hie Tan Hongfu Li 《International Journal of Infrared and Millimeter Waves》2000,21(2):219-230
Based on the coupled mode theory, this paper presents the study on the influence of input mode mixture in circular oversized waveguide mode converters. Three kinds of commonly used waveguide mode converters, including the waveguide mode converters with varying wall radius or small axis perturbations, and the waveguide mode converters with bent structures, are taken as the examples. The results show that the spurious input modes do not simply superimpose onto the output modes, and in some cases they may deteriorate the conversion efficiency for the main output mode. Methods for transforming such spurious input mode mixture simultaneously into the main output mode are also presented in this paper. 相似文献
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与伽利略不变性的超流体不同, 具有洛伦兹不变性的超流体中除了声子模之外, 还存在希格斯振幅模(Higgs amplitude mode). 在二维情况下, 由于存在十分剧烈的衰变成声子模的过程, 希格斯模是否仍然是一个能产生尖锐线性响应的激发子成为了一个问题. 近年来的进展最终对这一持续数十年的争论做出了肯定的回答, 证实了希格斯的可观测性. 在这里, 我们回顾一系列的数值方面的工作; 它们以二维超流体(superfluid)到莫特绝缘体(Mott insulator) 量子相变点(SF-MI QCP) 附近的具有洛伦兹不变性的超流体为对象, 成功探测到了希格斯模的线性响应信号. 特别是, 我们介绍了一种如何使用平衡态系统的蒙特卡罗算法计算强关联系统的延迟响应函数(retarded response function)的方法. 该方法主要包含两个核心步骤: 即通过路径积分表示下的蠕虫算法这一高效的蒙特卡罗算法计算平衡态系统的虚时间关联函数, 然后利用数值解析延拓方法从虚时间关联函数中获得实时间(实频率)的响应函数. 将该数值方法应用于二维SF-MI QCP附近的玻色-哈伯德模型(Bose-Hubbard Model), 结果表明尽管在超流相中, 希格斯模衰变过程非常剧烈, 但是在动能算符相对应的延迟响应函数的虚部中, 仍然可以观测到希格斯模所对应的尖锐的共振峰. 进一步的研究表明, 在莫特绝缘相, 甚至常流体相中, 也可能存在类似的共振峰信号. 由于可以在光晶格中超冷原子系统等凝聚态中观测到SF-MI QCP, 因此希格斯共振峰有望通过实验进行直接探测. 此外我们指出, 同样的希格斯共振峰还存在于所有和SF-MI QCP具有相同普适类((2+1)维相对论性U(1)临界性)的量子临界系统中. 相似文献
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Time-evolution of the vibrational states of two interacting harmonic oscillators in the local mode scheme is presented. A local-to-normal mode transition (LNT) is identified and studied from temporal perspective through time-dependent frequencies of the oscillators. The LNT is established as a polyad-breaking phenomenon from the local standpoint for the stretching degrees of freedom in a triatomic molecule. This study is carried out in the algebraic representation of bosonic operators. The dynamics of the states are determined via the solutions of the corresponding nonlinear Ermakov equation and a local time-dependent polyad is obtained as a tool to identify the LNT. Applications of this formalism to H2O, CO2, O3 and NO2 molecules in the adiabatic, sudden and linear regime are considered. 相似文献
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By virtue of the entangled-state basis and the ket-vector representation of the density operator, we solve the master equation of a driven damped harmonic oscillator. In this representation, the density operators are mapped to vectors of a two-mode Fock space whose first mode is the system mode and the second mode is a fictitious one. We derive the Glauber–Sudarshan P function of the quantum state. 相似文献
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V波段圆波导TE01模式激励器由矩形TE10模式到矩形TE20模式变换器和矩形TE20模式到圆波导TE01模式变换器组成。采用H面(磁面)转弯激励的方式实现矩形TE10模式到矩形TE20模式的变换;根据圆波导TE01模式的场分布特性,引入过模波导实现了矩形TE20到圆波导TE01的变换。计算结果表明设计的激励器转换效率在95%以上;模式纯度在98%以上的相对带宽可达4.2 GHz;其中在43.4 GHz处的最大转换效率为99.08%,纯度为99.20%。 相似文献