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本文讨论了群折射率存在的物理意义,指出群折射率不
仅包含了折射率概念而且还体现了折射率的色散性质,同样能作为材料本身的光学
性质参量.接着指出在折射率的白光干涉法测量中存在着忽视色散作用而导致的将群折射率
误认为折射率的情况.将群折射率与折射率区别开来,不仅可以消除折射率测量中所存在的
错误,而且可以突出色散现象在光传播时间特性上的意义.为此建立了折射率与群折射率的
相互变换关系,通过对于典型物质的折射率与群折射率变换关系的计算,说明二者在数值上
的差别甚至对于气体介质来说也是不能忽略的. 相似文献
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色散、群速与群折射率 总被引:3,自引:2,他引:1
本文讨论了群折射率存在的物理意义,指出群折射率不仅包含了折射率概念而且还体现了折射率的色散性质,同样能作为材料本身的光学性质参量.接着指出在折射率的白光干涉法测量中存在着忽视色散作用而导致的将群折射率误认为折射率的情况.将群折射率与折射率区别开来,不仅可以消除折射率测量中所存在的错误,而且可以突出色散现象在光传播时间特性上的意义.为此建立了折射率与群折射率的相互变换关系,通过对于典型物质的折射率与群折射率变换关系的计算,说明二者在数值上的差别甚至对于气体介质来说也是不能忽略的. 相似文献
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提出了使用用迈克尔逊干涉仪,改变光源入射方式及观测方式以获得稳定、清晰等厚干涉现象的方法.探究了在光路中插入的被测透明介质如何对等厚干涉条纹产生影响,并导出了被测介质厚度、折射率及旋转角度与等厚干涉条纹移动量之间的关系.实现对透明介质厚度、折射率进行简练、快速的同时测量. 相似文献
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白光照明载频照相法能产生相当于剪切干涉的莫尔条纹,本文提出用色散棱镜进行条纹的假彩色编码,使得测量上更灵敏和视觉上更舒适.首先讨论了以有限口径成像产生莫尔剪切干涉的方法,然后分析了色散假彩色编码的原理并导出了相位折射角和编码色之间关系,最后给出了实验结果. 相似文献
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提出了一种光纤折射率分布的测量方法,采用白光扫描干涉技术,并在参考镜上构造与光纤样品相同的结构来克服白光相干长度短的限制,优化了光路,提高了干涉条纹间的对比度。采用与白光干涉信号的包络线呈高斯分布的Morlet小波作为小波变换的母小波进行拟合处理,得到光纤与已知折射率的匹配液之间的相对高度。通过计算获得光纤的折射率分布,并对获得的数据采用光纤折射率分布的经典函数进行拟合,得到多模光纤和单模光纤的决定系数分别为0.997 2和0.996 4。最后将实验获得的结果与官方参数进行比较,误差为0.01%,表明该种方法测量的精度较高,完全可以用来测量光纤的折射率。 相似文献
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Qi-Liang He 《Optics Communications》2011,284(6):1714-1718
We investigate the entanglement dynamics and the phenomenon of entanglement sudden death in the two-photon Tavis-Cummings model with an added nonlinear kerr-like medium. It is shown that the phenomenon of entanglement sudden death can be controlled by the nonlinear kerr-like medium. Furthermore, the influence of dipole-dipole interaction on entanglement between atoms is also discussed. It is found that the phenomenon of entanglement sudden death can be weakened by the dipole-dipole interaction. Finally, we investigate the influence of kerr medium and dipole-dipole interaction on the three-partite entanglement of the system by making use of the state preparation fidelity. 相似文献
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Propagation of an acoustic wave in a soft medium permeated with air bubbles is theoretically investigated by using a self-consistent approach. The soft medium is assumed to be viscoelastic to estimate the effect of acoustic absorption on the acoustic localization in such a medium. The oscillation phases of bubbles are examined by employing a phase diagram method. A collective oscillation of the bubbles is observed once the acoustic localization occurs, which is known as a phenomenon of 'phase transition ', and such a phenomenon persists as we manually increase the viscosity factor of the soft medium. Therefore it is proven that the phenomenon of phase transition may serve as a unique criterion to effectively identify acoustic localization in a bubbly soft medium even in the presence of viscosity, and the directions of the phase vectors help to determine the extent of localization. This is of practical significance for experimental research studying the acoustic localization in such a medium, for which the presence of viscosity generally causes great ambiguity in distinguishing the effects of localization and acoustic absorption. 相似文献
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It is well known that scattering of a polychromatic plane wave by a random medium, i.e., by a medium whose refractive index varies randomly with position, may produce frequency shifts of spectral lines. It has been a common perception that a random medium is required for generation of such spectral shifts by scattering. In this Letter we show that such a phenomenon occurs even when the refractive index of the medium is a deterministic function of position. We also show that this phenomenon may be used to obtain information about the structure of a deterministic medium. 相似文献
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在n型四能级原子系统中,研究了电磁感应吸收的非线性理论.结果表明:探测光的拉比频率和衰减分配系数A影响非线性吸收,进而影响介质吸收.当探测光光强较弱时,介质吸收和线性吸收一致,均表现为电磁感应吸收特征;当探测光光强增大时,介质吸收和线性吸收不再一致,介质吸收曲线将会呈现出烧孔现象;当探测光光强增大到控制光(或信号光)光强时,介质吸收表现出很大的增益现象.同时,非线性吸收受到衰减分配系数A的影响,即使在探测场很弱的条件下,随着A值的减小,介质吸收由电磁感应吸收现象表
关键词:
电磁感应吸收
非线性吸收
增益现象
n型四能级原子系统 相似文献
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分析了二维各向同性均匀随机介质中柱面波的传播特性及局域化现象.用随机泛函理论,在频域内将随机介电起伏展开成柱坐标系下的Wiener积分式,将波场表示为内外行柱面波的线性和,求解二维Helmholtz波动方程,得到随机介电起伏对柱面波幅度与相位调制的解析表达.由柱面波能量的空间分布验证了波的局域化现象,并求解局域化长度.二维随机介质中平面波按柱面波展开的波转换方程与非随机介质中的情形有相似的表达,但具有随机介电起伏对幅度和相位的调制,并给出数值模拟结果. 相似文献
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We consider the radiation from oscillating electric and magnetic dipoles moving with constant velocity directed parallel or
antiparallel to the velocity of the surrounding medium. It is assumed that the medium in its rest frame is isotropic and has
no spatial dispersion. We obtain expressions for the spectral density of the radiated power. In the case of a nondispersive
medium, algebraic expressions for the total radiated power in the regime of “subluminal relative motion” are also obtained.
In particular, it is shown that the energy loss of a source is negative if it moves in the direction of the superluminal motion
of the medium and the source velocity is somewhat smaller than the medium velocity. It is noted that this phenomenon takes
place for a smaller difference between the velocities of the source and the medium compared with a similar phenomenon for
nonoscillating sources.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 4, pp. 316–328, May 2007. 相似文献
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Localisation and phase transition of acoustic waves in a soft medium containing air bubbles 下载免费PDF全文
We study via numerical experiments the localisation property of an acoustic wave in a viscoelastic soft medium containing randomly-distributed air bubbles. The behaviours of the oscillation phases of bubbles are particularly investigated in various cases for distinguishing efficiently the acoustic localisation from the effects of acoustic absorption caused by the viscosity of medium. The numerical results reveal the phenomenon of `phase transition' characterized by an unusual collective oscillation of bubbles, which is an effective criterion to unambiguously identify the acoustic localisation in the presence of viscosity. Within the localisation region, the phenomenon of phase transition persists, and a remarkable decrease in the fluctuation of the oscillation phases of bubbles is observed. The localisation phenomenon will be impaired by the enhancement of the viscosity factors, and the extent to which the acoustic wave is localised may be determined by appropriately analyzing the values of the oscillation phases or the amount of reduction of the phase fluctuation. The results are particularly significant for the practical experiments in an attempt to observe the acoustic localisation in such a medium, which is in general subjected to the interference of the great ambiguity resulting from the effect of acoustic absorption. 相似文献