小量子系统中弱光非线性效应及传播特性研究
文献类型：学位论文
| 作者 | 祁义红 |
| 学位类别 | 博士 |
| 答辩日期 | 2010 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 龚尚庆 |
| 关键词 | 量子相干调控 克尔非线性 弱光孤子 交叉相位调制 自聚焦 |
| 其他题名 | Investigation on nonliear effect and propagation property of weak-light in quantum system |
| 中文摘要 | 量子相干调控是近年来量子光学和激光物理等学科的交叉前沿研究领域。长期以来，为获得较强的非线性光学效应，人们主要利用强激光场与介质的非共振相互作用，即强光非线性光学。由于电磁诱导透明（EIT）效应的发现，在弱光条件下利用激光与介质的近共振相互作用产生强非线性光学效应成为可能，并由此开始了低光强水平下的非线性光学特性研究（弱光非线性光学）。近年来，基于EIT的弱光孤子也是量子相干调控和非线性光学领域的一个研究热点，具有重要的科学意义和潜在的应用价值。 本学位论文基于描述激光与物质相互作用的耦合麦克斯韦-薛定谔方程组，对多能级原子系统和半导体量子阱结构中量子调控弱光非线性效应和传播特性进行了深入研究，取得了一些创新性的研究成果。主要包括: 1. 研究了共振三能级Λ型原子系统中利用反相孤子间相斥相互作用操控弱光孤子。由于反相孤子之间的相斥相互作用，若反相的信号孤子与控制孤子在传输过程中相遇，则它们的传输方向在碰撞后会发生偏转。通过改变控制孤子的入射角度或者相对功率可以操纵弱光信号孤子的传输。 2. 通过周期性调制的控制场在EIT介质中实现弱光空间孤子的控制。控制场调制增强的区域相当于探测孤子的一个传输通道，探测孤子可以被周期势很好地囚禁在输入通道内。若控制场是一个均匀场，孤子会沿着其入射方向稳定传输。周期性调制的控制场在囚禁孤子方面具有很好的局域效率，这意味着其在控制孤子传输方面具有良好的开关性能。 3. 研究了三能级原子系统中弱光环形光束的聚焦和散焦动力学行为。利用一个强的控制场，在增强探测场非线性的同时很好的抑制了吸收，这使探测场在传输过程中保持了非常小的损耗。弱探测场在聚焦和散焦非线性机制下的传输可以通过改变激光场的失谐和控制场的拉比频率来调节。 4. 弱光探测脉冲在一个包含封闭环形框架的四能级冷原子系统中的传播特性依赖于驱动场的相对相位。通过选择合适的参数，在相对相位为0 时，探测脉冲可以传播足够长的距离而几乎没有任何损耗。然而，当相对相位由0 增大到π 时，探测场的吸收显著增大。若相对相位为π，探测脉冲在非常短的传播距离时就几乎被完全吸收。 5. 研究了非对称GaAs/AlGaAs双量子阱中基于子带间跃迁的线性和交叉相位调制三阶非线性极化率。由于Fano干涉的作用，不仅交叉相位调制依赖于激光场的相对相位，而且线性吸收也随相对相位变化，这里它们对相对相位的依赖周期为2π，与原子系统中以π为周期不同。在设计的量子阱系统中，单光子水平下的交叉相位调制的π相移可以在较短长度的量子阱中实现，而此时双光子吸收几乎为零。 |
| 英文摘要 | Study on quantum coherent control is the cross-research area of laser physics, quantum optics and other disciplines. In a long time, in order to obtain a strong nonlinear optical effect, the conventional method is to use off-resonant interaction between strong laser field and media (i.e. high-field nonlinear optics). Since the finding of electromagnetically induced transparency (EIT) effect, which provides the probability of obtaining strong nonlinear optical effect under weak light condition in coherent media, study on nonlinear optical properties at low light level has attracted great interest. In recent years, weak-light soliton based on EIT effect is also a hot research topic in the area of quantum coherent control and nonlinear optics. In this thesis, based on the Maxwell-Bloch equations describing the interaction between laser fields and media, we mainly investigate the quantum coherent control of nonlinear optical effects and propagation dynamics of laser fields in multi-level atomic system and semiconductor quantum wells. The main innovative and important results are listed as follows: 1. Based on the motion equations of atomic state amplitudes and wave equation, steering of the weak-light spatial soliton in a resonant lambda-type atomic system is studied. The repulsive property of out-of-phase solitons makes the propagation direction of signal soliton defect after collision. Steering of the weak-light signal soliton could be realized via controlling the input angle or power of the control soliton. 2. The weak-light soliton propagating in an EIT medium could be controlled via the periodic modulation of the control field. The periodic modulation modifies the refractive index to be periodic, which acts as periodic potential in transverse direction for the weak-probe soliton. In fact, the region of the modulation enhancement in a period is equivalent to a propagation channel for the soliton. The probe soliton could be well trapped in the input channel by the periodic potential. If there is no the periodic modulation, the soliton will propagate stably in its input direction. The good localization efficiency of the periodic potential implies its excellent switching performance. 3. The focusing and defocusing dynamics of weak-light ring-shaped beam are studied in a resonant three-level atomic system. By virtue of a strong control field, the enhanced nonlinearity and suppressed absorption are achieved for the weak probe field. The probe field propagating in the medium with focusing or defocusing nonlinearity could be manipulated via adjusting detunings and the Rabi frequency of the control field. 4. The propagation of the weak probe pulse in a cold four-level atomic system with a close-loop scheme could be controlled by the relative phase of the driven fields. By choosing parameters properly, the probe pulse may propagate over long distance without almost any loss when relative phase is 0. However, increasing the relative phase from 0 to π, the probe absorption increases greatly. When the relative phase is π, the probe pulse may be absorbed completely in a very short propagation distance. This property of phase-controlled probe absorption provides the possibility for realizing phase-controlled switching operation, which may have application in optical switching or optical storage devices. 5. The linear and third-order susceptibilities contributing to XPM based on intersubband transitions depend on the relative phase of the laser fields in GaAs/AlGaAs asymmetric double quantum wells (QWs) with a closed loop configuration. Due to Fano interference, not only the Kerr nonlinearity associated with XPM, but also the linear absorption becomes phase-dependent on the relative phase of the laser fields, and their periods are turned to be 2π but not π as that in atomic systems. By designing real QWs, we show that π phase shift in XPM under single photon level could be achieved within a short length of the QWs medium, while the two-photon absorption is nearly vanishing. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15652]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 祁义红. 小量子系统中弱光非线性效应及传播特性研究[D]. 中国科学院上海光学精密机械研究所. 2010. |
入库方式： OAI收割
来源：上海光学精密机械研究所
浏览0
下载0
收藏0
其他版本
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。