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基于掺铒光纤Bragg光栅的慢光和超光速传播的研究 被引量:1
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作者 国秀珍 卓仲畅 +1 位作者 姚大立 梁明 《光电子技术》 CAS 北大核心 2010年第4期217-221,共5页
光的群速度控制一直是重大研究课题之一。基于光纤的超光速和光速减慢带来新的技术突破。简述了超光速和光速减慢技术的发展。提出一种利用光泵浦改变掺铒光纤Bragg光栅中探测光的群速度的方法。推导了系统方程。讨论了光泵浦功率、光纤... 光的群速度控制一直是重大研究课题之一。基于光纤的超光速和光速减慢带来新的技术突破。简述了超光速和光速减慢技术的发展。提出一种利用光泵浦改变掺铒光纤Bragg光栅中探测光的群速度的方法。推导了系统方程。讨论了光泵浦功率、光纤Bragg光栅长度、掺杂Er3+离子浓度及光栅折射率调制幅度对群速度的影响。 展开更多
关键词 光纤光栅 慢光和超光速传播 光纤光学
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倒Y型四能级量子系统中亚光速和超光速传播现象的转换研究 被引量:1
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作者 孟冬冬 刘晓东 张森林 《物理学报》 SCIE EI CAS CSCD 北大核心 2011年第2期42-47,共6页
研究了探测场、耦合场和驱动场三场作用下倒Y型四能级量子系统的光学特性,利用数值模拟的方法探讨了外加相干驱动场的拉比频率和失谐量变化时系统对探测光场吸收特性的影响.通过绘制三维立体图,发现了探测光场的群速度在电磁诱导透明窗... 研究了探测场、耦合场和驱动场三场作用下倒Y型四能级量子系统的光学特性,利用数值模拟的方法探讨了外加相干驱动场的拉比频率和失谐量变化时系统对探测光场吸收特性的影响.通过绘制三维立体图,发现了探测光场的群速度在电磁诱导透明窗口处的变化规律,并且选择合适的驱动场拉比频率和失谐量,可以在理论上实现亚光速和真空光速以及超光速传播之间的转换. 展开更多
关键词 倒Y型四能级 群速度 超光速传播 光速传播
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会聚高斯光束的超光速传播
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作者 邓轩兵 邓冬梅 刘承宜 《激光与光电子学进展》 CSCD 北大核心 2013年第6期168-172,共5页
研究了经无像差透镜聚焦的高斯光束在焦平面附近的群速度与相速度,阐明了由于衍射导致相位变化从而产生的超光速传播现象。给出了透镜几何焦点与光束束腰间距的微小变化对相速度与群速度的影响。
关键词 物理光学 超光速传播 会聚高斯光束 相位异常
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微波脉冲以超光速传播
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作者 咏涛 《激光与光电子学进展》 CSCD 2002年第3期63-64,共2页
关键词 光脉冲 微波脉冲 超光速传播
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英国 科学家拍摄到微粒超光速传播现象
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《科学家》 2017年第2期J0004-J0004,共1页
1月24日,英国科学家首次拍摄到奇特的光线音爆现象,当微粒以超音速传播时出现光线散射。“马赫锥”是超快微粒发出冲击波时形成的,在周围散发光线,
关键词 英国科学家 超光速传播 微粒 拍摄 光线散射 音爆现象 音速 冲击波
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Superluminal Propagation in Er^(3+)-doped Fiber Bragg Grating
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作者 ZHUO Zhong-chang SU Xue-mei +2 位作者 YU Yong-sen ZHENG Wei ZHANG Yu-shu 《Semiconductor Photonics and Technology》 CAS 2005年第3期145-149,共5页
The method to pump the FBGT written into an Er^3+-doped optical fiber is proposed to increase the group velocity of a probing pulse based on the facts that pump-induced process changes the refractive index and disper... The method to pump the FBGT written into an Er^3+-doped optical fiber is proposed to increase the group velocity of a probing pulse based on the facts that pump-induced process changes the refractive index and dispersion associated with the ^4I15/2-^4I12/2 transition in Er^3+-doped optical fiber.The system equations are derived.The effects of pump power and doping concentration on the group velocity are discussed. 展开更多
关键词 Bragg grating SUPERLUMINAL PUMP
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光子晶体中缺陷的色散导致的群速度降低 被引量:9
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作者 安丽萍 刘念华 《光学学报》 EI CAS CSCD 北大核心 2003年第11期1287-1290,共4页
利用传输矩阵方法计算了包含色散媒质缺陷的一维光子晶体的复透射系数 ,其中色散媒质用洛仑兹振子模型描述。计算了由复透射系数定义的等效复折射率并由此研究了频谱位于缺陷模频率附近的光脉冲的群速度。结果发现 ,由于缺陷模附近的透... 利用传输矩阵方法计算了包含色散媒质缺陷的一维光子晶体的复透射系数 ,其中色散媒质用洛仑兹振子模型描述。计算了由复透射系数定义的等效复折射率并由此研究了频谱位于缺陷模频率附近的光脉冲的群速度。结果发现 ,由于缺陷模附近的透射谱敏感地依赖于缺陷层的光学厚度 ,而缺陷层的色散使缺陷层光学厚度随频率变化而改变 ,从而使包含缺陷的光子晶体的等效色散性质明显地依赖于缺陷的色散行为。由于光脉冲是由多种频率成分的单色场迭加构成的 ,透射脉冲由各单色场透射后重新迭加构成 ,因此波包的传播由介质的等效色散性质决定。与包含无色散缺陷的光子晶体相比 ,缺陷的色散可导致极慢的群速度。通过改变振子强度 ,群速度可从极慢光速转变为超光速 (superluminal)。 展开更多
关键词 光子晶体 群速度 色散 缺陷 传输矩阵法 复透射系数 能带结构 超光速传播 麦克斯韦方程 色散媒质
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反常色散介质中信息的传递 被引量:2
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作者 黄超光 张元仲 《中国科学(G辑)》 CSCD 2003年第2期110-116,共7页
研究了反常色散介质中信息的传递及信号速度。我们认为波包包络线的不连续点及包络线的任一阶导数的不连续点都是一个脉冲所携带的区别于其他脉冲的信息。信号速度不应超过这些不连续点移动的速度。作为例子,具体研究了包络线为三角形... 研究了反常色散介质中信息的传递及信号速度。我们认为波包包络线的不连续点及包络线的任一阶导数的不连续点都是一个脉冲所携带的区别于其他脉冲的信息。信号速度不应超过这些不连续点移动的速度。作为例子,具体研究了包络线为三角形的脉冲及由三段二次曲线构成的脉冲在具有双增益峰的反常色散稀薄气体中的传播。研究结果表明包络线及其一阶导数、二阶导数的不连续点在所研究的介质中都以真空光速传播。此外,还对波包变形是否可忽略提出了一个理论上的判据。 展开更多
关键词 反常色散介质 信息传递 信号速度 光脉冲 超光速传播 包络线 波包变形
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Nonlinear optical properties and superluminal propagation in the ruby 被引量:1
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作者 GAO Feng1,2,3,XU JingJun1,2,3,ZHANG GuoQuan1,2,3 & ZHANG WenDing1,2,3 1 Photonics Center,College of Physics Science,Nankai University,Tianjin 300457,China 2 The Key Laboratory of Advanced Technique and Fabrication for Weak-Light Nonlinear Photonics Materials of Ministry of Education,Nankai University,Tianjin 300457,China 3 Tianjin Key Laboratory of Photonics Materials and Technology for Information Science,Nankai University,Tianjin 300457,China 《Chinese Science Bulletin》 SCIE EI CAS 2010年第6期473-477,共5页
In this review article,we summarized the study of the weak light nonlinear properties associated with group velocity change in the ruby.The ruby could be reduced to a two-level system,in which population oscillations ... In this review article,we summarized the study of the weak light nonlinear properties associated with group velocity change in the ruby.The ruby could be reduced to a two-level system,in which population oscillations could lead to a subluminal result.With the modulated TEM00 beam introduced into the ruby,self-phase modulation together with Fraunhofer diffractions and nondegenerate two-wave coupling between different spatial frequency components of the beam occurs at the same time.Population oscillations,self-phase modulation together with Fraunhofer diffractions and nondegenerate two-wave coupling mechanism competes with each other,which brings a new phenomenon of self-superluminal group velocity propagation in the ruby. 展开更多
关键词 非线性光学性质 超光速传播 红宝石 自相位调制 TEM00模 速度变化 光束耦合 空间频率
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Phase-Controlled Transparent Superluminal Light Propagation in a Doppler-Broadened Four-Level N-Type System 被引量:1
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作者 Lida Ebrahimi Zohravi Majid Abedi Mohammad Mahmoudi 《Communications in Theoretical Physics》 SCIE CAS CSCD 2014年第4期506-516,共11页
The propagation of a weak probe field in a four-level N-type quantum system in the presence of spontaneously generated coherence(SGC) is theoretically investigated. The optical properties of the system are studied and... The propagation of a weak probe field in a four-level N-type quantum system in the presence of spontaneously generated coherence(SGC) is theoretically investigated. The optical properties of the system are studied and it is shown that the group velocity of light pulse can be controlled by relative phase of applied fields. By changing the relative phase of applied fields, the group velocity of light pulse changes from transparent subluminal to the transparent superluminal light propagation. Thus, the phase-controlled absorption-free superluminal light propagation is obtained without applying an incoherent laser fields to the system. The propagation of a weak probe light pulse is studied by solving the Maxwell's wave equation on numerical grid in space and time. Moreover, we study the third order self- and cross-Kerr susceptibility of probe field and calculate the nonlinear cross-phase shift for different values of intensity of applied fields. In addition, we take into account the effect of Doppler broadening on the light pulse propagation and it is found that a suitable choice of laser propagation directions allows us to preserve our results even in the presence of Doppler effect. It is demonstrated that by increasing the Doppler width of distribution to the room temperature,the dispersion changes from transparent subluminal to transparent superluminal light propagation which is our major motivation for this work. 展开更多
关键词 coherent control spontaneously generated coherence SUPERLUMINAL
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The manipulation of light pulse from subluminal to superluminal propagation in a degenerate two-level Cs atomic system
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作者 ZHANG Jun Xiang JIANG Qi Chang +2 位作者 LIU Chao ZHANG Xin Sheng LIU Jin Hong 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2014年第12期2246-2250,共5页
We experimentally demonstrate the propagation of light pulse from subluminal to superluminal light based on quantum coher- ence in a degenerate two-level atomic system in a Cs vapor cell. It is shown that the group ve... We experimentally demonstrate the propagation of light pulse from subluminal to superluminal light based on quantum coher- ence in a degenerate two-level atomic system in a Cs vapor cell. It is shown that the group velocity of light pulse can be switched from subluminal to superluminal propagation via changing the coupling field from a traveling wave to a standing wave, while can also be continuously manipulated by varying the intensity of two waves superposed to form a standing wave. The observed maximum delay and advance times are about 0.45 and 0.54 μs, corresponding to the group velocity of v8 = 168 km/s and ve =-138 krrt/s, respectively. This investigation may have the practical applications of devices for optical tunable delay lines, optical switching and optical buffering. 展开更多
关键词 group velocity SUBLUMINAL SUPERLUMINAL quantum coherence standing wave
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Roles of Atomic Injection Rate and External Magnetic Field on Optical Properties of Elliptical Polarized Probe Light
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作者 R.Karimi S.H.Asadpour +1 位作者 S.Batebi H.Rahimpour Soleimani 《Communications in Theoretical Physics》 SCIE CAS CSCD 2016年第1期57-65,共9页
In this paper we investigate the optical properties of an open four-level tripod atomic system driven by an elliptically polarized probe field in the presence of the external magnetic field and compare its properties ... In this paper we investigate the optical properties of an open four-level tripod atomic system driven by an elliptically polarized probe field in the presence of the external magnetic field and compare its properties with the corresponding closed system.Our result reveals that absorption,dispersion and group velocity of probe field can be manipulated by adjusting the phase difference between the two circularly polarized components of a single coherent field,magnetic field and cavity parameters i.e.the atomic exit rate from cavity and atomic injection rates.We show that the system can exhibit multiple electromagnetically induced transparency windows in the presence of the external magnetic field.The numerical result shows that the probe field in the open system can be amplified by appropriate choice of cavity parameters,while in the closed system with introduce appropriate phase difference between fields the probe field can be enhanced.Also it is shown that the group velocity of light pulse can be controlled by external magnetic field,relative phase of applied fields and cavity parameters.By changing the parameters the group velocity of light pulse changes from subluminal to superluminal light propagation and vice versa. 展开更多
关键词 jelliptically polarized field magnetic field phase difference
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