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Theoretical analysis of hot-image effect in a high-power laser system with cascaded nonlinear medium
We present a universally applicable and quick method to forecast the intensity and location of the hot-image effects in a high-power laser system structured by cascaded Kerr medium plates. The analytical expressions for the locations and the peak intensity of the hot-images are deduced by using propagation matrix method. The results are useful for laser designers to estimate and minimize the threat of optical damage. Theoretical analysis demonstrates that a maximum of N hot-images may appear in a laser system structured by N cascaded Kerr medium plates and the distance between two adjacent hot-images is two times the interval between two adjacent Kerr medium plates. The number and locations of the hot-images are related with the number of the Kerr medium plates, the distance from the scatterer to the front of the first Kerr medium plate, and the interval between two adjacent Kerr medium plates. The peak intensity of the hot-images depends on the number of the Kerr medium plates, the B-integral of each Kerr medium plate, the amplitude and phase modulation coefficients of the scatterer and the peak intensity of the input beam. The hot-image effects in a laser system with cascaded Kerr medium plates from two to eight are discussed in detail and numerically analyzed. Numerical simulation results are in agreement with the theoretical results. 相似文献
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对高功率激光系统中存在的一种类似于小尺度自聚焦的非线性过程“热像”效应进行了理论分析和模拟计算。当一束经过遮光物调制的激光光束通过非线性介质后,在随后的光路上将产生一个亮点,即“热像”。“热像”处的光强比背景光强大几倍,因此位于“热像”附近位置的光学元件很可能遭受损伤。从全息成像的角度对“热像”的形成过程进行了分析。结果表明:“热像”的位置处于以非线性介质为中心与遮光物大约对称的地方,“热像”的光强是原始光强的(1+B)2倍。计算机模拟与理论计算结果吻合较好,验证了上述结果。 相似文献
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对高功率激光系统中存在的一种类似于小尺度自聚焦的非线性过程“热像”效应进行了理论分析和模拟计算。当一束经过遮光物调制的激光光束通过非线性介质后,在随后的光路上将产生一个亮点,即“热像”。“热像”处的光强比背景光强大几倍,因此位于“热像”附近位置的光学元件很可能遭受损伤。从全息成像的角度对“热像”的形成过程进行了分析。结果表明:“热像”的位置处于以非线性介质为中心与遮光物大约对称的地方,“热像”的光强是原始光强的(1+B)2倍。计算机模拟与理论计算结果吻合较好,验证了上述结果。 相似文献
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实验研究宽频带脉冲光束通过非线性介质时的非线性热像的形成过程,揭示了光束入射功率和脉冲宽度、介质厚度等因素对热像光强和位置的影响. 结果表明,与单纵模激光束一样,在宽频带脉冲光束情形下,非线性介质上游元件的模糊斑调制也可导致在下游共轭位置形成热像. 热像光强随入射光束功率的增加而增加;若脉冲能量一定,则热像光强随脉冲宽度的增加而减弱;若脉冲峰值功率一定,则热像光强随脉冲宽度的增加而增强.
关键词:
高功率激光
热像
宽带光束
小尺度自聚焦 相似文献
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通过理论分析和数值模拟方法,研究了高功率激光系统中的非线性“热像”效应. 利用菲涅耳-基尔霍夫衍射积分和非线性近轴波动方程,在远场近似及光学薄近似条件下,得出了位相调制产生“热像”出现的位置及强度满足的解析关系.结果表明,“热像”形成在非线性介质后与衍射物对称的位置,其强度可能比振幅调制产生“热像”的强度大几倍. 通过计算机模拟,并与理论预测结果进行比较,显示两者符合较好. 同时给“热像”的形成过程赋予了明确的物理意义,指出“热像”的形成类似于同轴位相夫琅禾费全息过程.
关键词:
“热像”效应
全息成像
小尺度自聚焦
高功率激光 相似文献
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高斯光束在克尔型非线性介质中的演化特性 总被引:1,自引:1,他引:1
由光束在克尔型吸收介质中传输的非线性薛定谔方程,推导了高斯光束注入介质后满足的耦合方程,并分别在不考虑吸收和高阶展开项的情况下,对脉冲的腰斑半径的演化进行了理论分析。发现当注入脉冲满足一定的条件时,脉冲可以以“孤波”的形式传播。当考虑吸收和高阶展开项时,脉冲不存在“孤波”形式,且存在一个阈值,低于阈值的输入,脉冲发生自聚焦;对高于阈值的输入,腰斑半径随着距离的增加而增加,聚焦趋势根本就不存在。 相似文献
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A new method for double image encryption is proposed that is based on amplitude-phase hybrid encoding and iterative random phase encoding in fractional Fourier transform (FrFT) domains. In the iterative random phase encoding operation, a binary random matrix is defined to encode two original images to a single complex-valued image, which is then converted into a stationary white noise image by the iterative phase encoding with FrFTs. Compared with the previous schemes that uses fully phase encoding, the proposed method reduces the difference between two original images in key space and sensitivity to the FrFT orders. The primitive images can be retrieved exactly by applying correct keys with initial conditions of chaotic system, the pixel scrambling operation and the FrFT orders. Computer simulations demonstrate that the encryption method has impressively high security level and certain robustness against data loss and noise interference. 相似文献
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本文讨论了考虑Kerr介质的非线性耦合作用时k光子J-C模型中原子信息熵的演化性质.通过计算得到了原子信息熵随时间的演化特性,分析表明Kerr效应越大,原子信息熵明显减小.多光子过程使原子的信息熵增大,而相干态光场的强度对其也有明显的影响.并且对这些影响的物理机制作了必要的解释. 相似文献
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为了测量卫星姿态不稳定或振动等原因引起的空间相机亚像元像移,设计了基于联合变换相关器的像移测量试验系统。阐述了该方法的数学原理,面阵CCD的安装位置以及输入图像序列的获取方法。根据相关参数确定了试验系统的傅里叶透镜结构和参数,最终设计了试验系统。应用线性插值和像元合并方法获得具有亚像元像移的图像果表明,像移测量的精度不随景物的内容而变化,测量得到的像移误差均方根值<0.2pixel。 相似文献
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We have established the master equation for the micromaser with a Kerr medium,we have studied the photon statics of the micromaser with a Kerr medium field and analysed the influence of the Kerr effect on the photon statistics,The influence of the Kerr effect on the photon statistics is different in two regimes,In the thermal-atom regime,the Kerr effect produces quantum noise,and decreases the mean photon number.In the ultracold-atom regime,with the increase of the nonlinear parameter of the Kerr medium,the stability of the mean photon number and the normalized variance enhances the mean photon number,and the normalized variance exhibits collapse-revival phenomena periodically,their resonance peaks become lower,and the photon statistics of more and more regions are sub-Poissonian. 相似文献
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地基激光空间碎片清除和利用激光辐射把转换的太阳能从空间轨道输运到地面等应用中,不可避免地遇到高功率激光在非均匀大气中的传输问题。由于激光功率已远远超过大气非线性自聚焦临界功率,大气自聚焦效应是影响光束质量的一个重要物理因素。概述了近年来国内外高功率激光在非均匀大气中上行或下行传输的自聚焦效应研究进展,主要介绍了高功率激光在非均匀大气中的传输模型、理论基础、数值和解析研究方法,着重介绍了自聚焦效应对激光传输特性和光束质量的影响,并总结了优化靶面光束质量的方案。此外,还介绍了大气群速度色散效应和大气湍流效应等物理因素对激光光束质量的影响。最后,还提出了该领域值得进一步深入研究的一些问题。
相似文献15.
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利用不变量方法研究了充满Kerr介质的高Q腔中双模场与二能级原子非共振相互作用系统,得到了该系统的态矢、时间演化算符、原子布居数和双模场光子数随时间演化式. 相似文献
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Optics has already been established as a potential candidate for conduction of digital logic and arithmetic operation in communication and computation processes. Different proposals have been reported by different scientists to make optics meaningful signal for conduction of the above operations. As it is well known that the memory device is a basic building block of any computation and communication system hence developing systems such as digital memory, multivibrator, etc. are the obvious requirements for optical communication as well as computation systems also. As the role of switching devices is an essential part of any processing system, many proposals were seen where all-optical switches using the combination of linear and non-linear materials were used, to implement the logic elements.In this context, the authors propose a new scheme for implementation of an all-optical mono-stable multivibrator using the non-linear material based switches and high refractive index based material. This multivibrator can generate a time pulse of definite width. 相似文献
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采用数值计算的方法,研究了有Kerr介质存在时负二项式光场与二能级原子依赖强度耦合相互作用系统中原子布居反转的时间演化规律,讨论了Kerr介质和光场参量对原子反转的时间演化的影响. 相似文献
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Lifu Zhang Xiquan Fu Jianqin Deng Shuangchun Wen Dianyan Fan 《Optics Communications》2011,284(8):2210-2214
We experimentally investigate the evolution of spatial modulation of broadband laser pulses with different pulse durations through a medium with non-instantaneous Kerr nonlinearity. By modifying the input laser pulse width, we observe the nonlinear growth of the spatial stripes that arise from interference with different modulation frequencies, and then obtain the gain spectra of the spatial modulation which clearly reveal the influence of relaxation effect on spatiotemporal modulation instability. We find that all gain spectra have the similar fastest growing frequency, but they have tails at higher frequency region in which the growth rate of gain is bigger for shorter pulse duration. The experimental results are confirmed by the perturbational analysis. 相似文献
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运用全量子理论并结合数值计算方法,研究了Kerr介质腔中处于Bell态的两个全同二能级纠缠原子与双模纠缠相干光场相互作用系统的原子偶极压缩特性.讨论了双原子体系的初态、光场的平均光子数、双模纠缠相干光场的纠缠程度以及Kerr介质与双模光场的耦合强度对原子偶极压缩特性的影响.结果表明:双原子体系的初态为|β11>时,不会出现偶极压缩效应;初态为|β00>,|β01>或|β10>时在一定条件下可能出现原子压缩效应,且此时原子压缩的特性与Kerr介质与双模光场的耦合强度、初始光场的平均光子数、双模纠缠相干光场的纠缠程度有关.
关键词:
量子光学
Bell态
双模纠缠相干光场
Kerr介质 相似文献