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运用数值模拟方法讨论了控制场的变化对M型五能级原子系统相对于探测场的吸收和色散等光学性质的影响.结果表明,改变控制场拉比频率时,系统的吸收和色散性质会发生规律性变化.在特定区域会呈现电磁感应透明窗口,其中透明窗口的数量与外加控制场数目成正比,而透明窗口宽度与拉比频率大小相关,拉比频率越大,透明窗口越平坦,当拉比频率减小,透明窗口变窄同时介质色散增强可获得慢光速光脉冲. 相似文献
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采用了一个闭合的Y型四能级原子系统,在多模光场的作用下,利用量子相干技术使其实现介质的左手效应,使介质具备左手材料特性.在相互作用表象下,考虑偶极近似和旋转波近似利用密度矩阵方程并结合相关条件下的有关公式进行理论计算.数值模拟结果显示:在合适的参量条件下,介质的相对介电常量和相对磁导率可以同时出现负值,产生了左手效应,相应的介质转化为左手材料.在弱探测场条件下,当探测光的拉比频率增加时,介质实现左手效应的频率范围减小并且与之相对应的折射率和吸收系数也发生变化.通过讨论在左手效应成立的条件下介质对光场的吸收和增益问题,结果表明:在弱探测场条件下,利用电磁诱导的方法也可以实现介质的左手效应,使得左手材料在实验上的实现也得到了进一步的扩展,同时也扩展了电磁诱导的应用领域. 相似文献
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A closed four-level system in atomic vapor is proposed, which is made to possess left handedness by means of the technique of quantum coherence. The method of density matrix is utilized in view of the rotating-wave approximation and the effect of local-field in dense gas. The result of the numerical simulation shows that the negative permittivity and negative permeability of the medium can be achieved simultaneously (i.e., the left handedness) in a wider frequency band under appropriate parameter conditions. Furthermore, when analyzing the dispersion property of the left-handed material, we find that the probe beam can be controlled to change from superluminal to subluminal or vice versa via changing the detuning of the probe field. 相似文献
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Wider frequency domain for negative refraction index in a quantized composite right–left handed transmission line 下载免费PDF全文
The refraction index of the quantized lossy composite right-left handed transmission line(CRLH-TL) is deduced in the thermal coherence state. The results show that the negative refraction index(herein the left-handedness) can be implemented by the electric circuit dissipative factors(i.e., the resistances R and conductances G) in a higher frequency band(1.446 GHz≤ω≤ 15 GHz), and flexibly adjusted by the left-handed circuit components(Cl, Ll) and the right-handed circuit components(Cr, Lr) at a lower frequency(ω = 0.995 GHz). The flexible adjustment for left-handedness in a wider bandwidth will be significant for the microscale circuit design of the CRLH-TL and may make the theoretical preparation for its compact applications. 相似文献
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