共查询到18条相似文献,搜索用时 78 毫秒
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以相干诱导光子带隙结构为工作基础,提出了一种可对两个弱光信号的传播路径同时进行动态调控的新型全光路由控制方案。利用描述光波在空间周期介质中相干散射的传输矩阵理论,结合描述单频激光与多能级原子共振相互作用的密度矩阵方程,计算了作为控制媒介的相干驱动超冷原子系综的稳态反射光谱和稳态透射光谱。结果表明,通过改变两个较强相干激光的空间模式、强度和频率等参数,可在探测跃迁共振频率附近建立反射率约为95%或者透射率约为95%的两个特殊频带。对这样的相干诱导高反射带和高透射带进行了实时动态调控,可根据需要引导两个不同频率的弱光信号进入指定的网络通道。该方案很好地满足了在量子信息处理领域对弱光信号进行全光路由控制时的低损耗和低形变要求。 相似文献
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针对马铃薯损伤部位随机放置会影响检测精度的问题,提出从正对相机、背对相机及侧对相机三个方向,应用透射和反射高光谱成像技术采集马铃薯图像,进行透射和反射高光谱成像的马铃薯损伤检测比较研究。对透射和反射高光谱图像进行独立成分(IC)分析和特征提取,利用所得特征对反射图像进行二次IC分析,对透射和反射光谱进行变量选择,最终分别建立基于反射图像、反射光谱、透射光谱的马铃薯损伤定性识别模型;对识别准确率高的模型做进一步优化,采用子窗口排列分析(SPA)算法对透射光谱的特征做二次选择得到3个光谱变量,并建立任意放置的马铃薯损伤识别最优模型。试验结果表明,基于反射图像、反射光谱建立的模型识别准确率较低,其中基于反射图像的马铃薯碰伤,侧对相机识别准确率最低为43.10%;基于透射光谱信息建立的模型识别准确率较高,损伤部位正对、背对相机的识别准确率均为100%,侧对相机为99.53%;马铃薯损伤识别最优模型对任意放置的损伤识别准确率为97.39%。应用透射高光谱成像技术可以检测任意放置方向下的马铃薯损伤,该研究可为马铃薯综合品质的在线检测提供技术支持。 相似文献
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我们在~(87)Rb冷原子系综中进行了关联光子对的产生和测量。通过自发拉曼散射过程,产生了一个Stokes光子和一个原子自旋波激发。利用电磁感应透明效应将存储在原子系综中的自旋波转化为一个anti-Stokes光子。在两相互正交的偏振基下,测量了Stokes光子和anti-Stokes光子之间的交叉关联函数。实验结果表明,交叉关联函数g~(2)达到~75,表现了强的非经典关联。基于现场可编程门阵列(FPGA)的自编程的多通道符合器被用于光子脉冲信号的采集和逻辑处理,大大提高了偏振关联光子对的产生和测量速度,为以后量子中继技术中的高效信息处理提供了重要基础。 相似文献
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提出了一种基于量子相干控制吸收的对准Λ型四能级原子进行二维局域化方案. 利用密度矩阵微扰理论, 得到了确定原子空间位置信息的筛选函数解析表达式. 在缀饰态表象中, 分析了在相干控制场作用下原子初始状态对原子局域的影响. 数值模拟了控制场参量对原子局域化结果的影响. 研究发现原子局域化结果与初始时刻在控制场作用下原子在下能态的布局、下能级间产生的极化密切相关; 不管探测场与耦合场是否满足电磁感应透明配置条件, 通过改变控制场中的行波场的振幅和探测场的失谐量, 均可实现高精度原子局域化, 在亚波长范围内测量到原子的概率达到100%. 相似文献
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采用传输线模型对高阻表面表面阻抗进行建模,准确计算垂直入射条件下高阻表面的反射相位.在垂直入射条件下,过孔的影响可以忽略,将高阻表面等效为具有容性的贴片阵与具有感性的介质层的并联,利用传输线原理求得高阻表面的反射系数,再得到其反射相位.计算了不同参数的高阻表面反射相位,传输线模型计算反射相位与数值方法计算结果符合较好.制作了不同参数的高阻表面并测量其反射相位,实验结果表明传输线模型计算反射相位结果与测量结果基本符合,证明了传输线模型的正确性.
关键词:
高阻表面
反射相位
传输线模型 相似文献
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The laws of refection and transimission on a moving interface between two nonvacuum medium are studied and the new method, which can be used for handling reflection and transimission on the moving interfaces between the vacuum-nonvacuum media and between two nonvacuum medium is suggested. The formula of reflection and transmission coefficients that suitable for both cases are derived. The present paper not only enriches electrodynamical theory, but also laies the foundation of optical waveguide modulators and other similar device. 相似文献
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The laws of refection and transimission on a moving interface between two nonvacuum medium are studied and the new method, which can be used for handling reflection and transimission on the moving interfaces between the vacuum-nonvacuum media and between two nonvacuum medium is suggested. The formula of reflection and transmission coefficients that suitable for both cases are derived. The present paper not only enriches electrodynamical theory, but also laies the foundation of optical waveguide modulators and other similar device. 相似文献
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A special kind of one-dimensional (1D) magnetic photonic crystal (MPC) is investigated. The refractive indices of the alternating layers in such a MPC are equal. As a result, the stop-band edges of TE mode coincide with those of TM mode, and the stop-bands for both modes expand as the incident angle increases. Based on the incident angle domain method, the omnidirectional total reflection (ODTR) band determined by the wave impedance ratio between the composites can be enlarged substantially using a heterostructure in which the stop-band edges of the sub-PCs can be completely adjacent at any incident angle. Moreover, the requirement of ODTR of each sub-PC is unnecessary, which extends the range of materials; that is, the wave impedance ratio between the composites and the refractive index ratio between the composites and the incident media can be much lower than that required in a single periodic structure. 相似文献
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Optical control of light propagation in photonic crystal based on electromagnetically induced transparency 下载免费PDF全文
A kind of photonic crystal structure with modulation of the refractive index is investigated both experimentally and theoretically for exploiting electromagnetically induced transparency(EIT).The combination of EIT with periodically modulated refractive index medium gives rise to high efficiency reflection as well as forbidden transmission in a threelevel atomic system coupled by standing wave.We show an accurate theoretical simulation via transfer-matrix theory,automatically accounting for multilayer reflections,thus fully demonstrate the existence of photonic crystal structure in atomic vapor. 相似文献
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L. Ward 《Optics & Laser Technology》1996,28(3):229-232
Abelès' equations for the phase changes on reflection and transmission, Fs, Fp, Xs and Xp at thin films have been rearranged into geometrical form in the ε1, ε2 plane. The contours of constant Fs and Fp are a series of circles whilst Xs and Xp can be represented by straight lines. When considering the same functions in the n, k plane, fs and Fp become quartics in new axes, n′ and k′, obtained by rotating the n and k axes through an angle a given by tan . A similar transformation applied to Xs and Xp generates hyperbolae in the n′, k′ plane. 相似文献