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本文证明了,只要测量了脉冲光强的二阶相关函数G~(2)(τ)和单延迟的三阶相关函数G~(3)(τ),便可以恢复超短激光脉冲的强度波形。并提出一种恢复脉冲波形的计算方法,编制了计算机程序,对实验数据作了处理,证实这种计算方法是可行的。在此基础上建议一种通过相关测量确定超短激光脉冲波形的新型仪器。 相似文献
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在单模光纤反常色散区,首次推出了带有初始啁啾的高斯脉冲在二阶,三阶速度色散效作用产生的啁啾解析表达式,用数值法模拟了光纤中啁啾演变过程,研究结果表明,二阶,三阶色散导致非线性啁啾,三阶色散只在脉冲沿附产生啁啾极值,从而使脉冲在前后沿产生振荡结构,当具有负初始啁呼的高斯脉冲入射时,在脉冲中心小区域内净啁啾等于零,可形成孤子。 相似文献
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本文提出用单延迟三阶、四阶相关函数,经傅里叶交换获得脉冲形状的方法.在实验上用克尔快门测量了YAG被动锁模激光脉冲的三阶和四阶相关函数,并用该方法获得脉冲形状.文中还讨论了脉冲对称性对恢复脉冲的影响. 相似文献
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以脉冲半导体激光器为例,对3种测量激光脉冲时基抖动技术进行了对比实验。这3种测量技术分别是:基于宽带取样示波器的时基抖动测量技术;基于相位比较检相器的相位噪声测量技术和基于频谱仪的谐波频谱分析技术。对比研究发现:基于宽带取样示波器的时基抖动测量技术适用于脉冲宽带及脉冲抖动较大的光脉冲;基于频谱仪的谐波频谱分析技术适用于低重复频率光脉冲的抖动测量;基于相位比较检相器的相位噪声技术测量精度高、动态范围大、结果可靠,对于高重复频率的超短光脉冲,建议选用相位噪声测量技术测量激光脉冲的时基抖动。 相似文献
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用脉冲回波重叠法测量了钛合金(TC-6)的二阶、三阶弹性常数。实验中发现dμ/dp<0(p<0.17 GPa),dμ/dp>0(p>0.17 GPa)。 相似文献
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利用同步辐射角散X射线衍射技术测量了室温条件下0---0.74 GPa 压力范围内Ce的等温压缩线.发现γ-Ce的室温等温压缩线呈外凸形, 这是由其纵波声子模软化所致.利用超声测量得到的体弹性模量随压力变化的规律, 对实验所得到的压力与体积数据, 用二阶和三阶Murnaghan 方程、 二阶和三阶Birch 方程、 三阶Xu方程以及二阶Vinet方程进行比较, 并且对这些状态方程得到的体弹性模量随压力的变化规律与超声实验的结果相对比, 发现三阶Murnaghan 方程和三阶Xu方程对γ-Ce最适用. 相似文献
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色散缓变光纤中飞秒孤子压缩与稳定传输 总被引:4,自引:1,他引:3
运用数值方法研究了色散缓变光纤中飞秒基本孤子的传输特性,发现基本孤子脉冲不仅能被压缩,而且压缩光脉冲能保持脉宽不变转输即稳定传。光脉冲压缩过程中,发现三阶色散效应有较大的影响。适当地选取色散缓变光纤结构参数可能获得高质量的超短压缩光脉冲。对压缩光脉冲稳定伟机理探索表明,光纤二阶色散纵向变化率,三阶色散与喇曼自散射效应共同作用导致压缩光脉冲稳定传输。 相似文献
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The auto triple correlation has several fundamental advantages over the ordinary autocorrelation of second order. We present an optoelectronic processor for the computation of the auto triple correlation. 相似文献
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PedestalMeasurementofLaserPulsesWANGYiminZHANGZhengquanXUZhizhan(ShanghaiInstituteofOptics&FineMechanics,ChineseAcademyofScie... 相似文献
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A gaussian memory function is used to compute the viscosity of dense fluid argon over a large region of states from the Lennard-Jones potential and the radial distribution function. The superposition approximation is used to evaluate the triplet correlation function and estimates of the errors introduced by this approximation are investigated. The agreement with experimental viscosities is quite satisfactory in the liquid region, but less so at lower densities and higher temperatures. The computed stress autocorrelation function exhibits those characteristics which are known from molecular dynamics studies. The stress autocorrelation remains monotonic even close to the triple point, where the same memory function leads to the well-known backscattering behaviour in the velocity autocorrelation function. This, too, is in agreement with the results of molecular dynamics. 相似文献
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V. I. Bardyshev 《Acoustical Physics》2010,56(2):196-197
Results of measuring normalized autocorrelation functions and frequency correlation functions of slow random variations in
the ambient noise levels are presented. The measurements were carried out in the shelf zone of the Pacific Ocean, near Shikotan
Island, at a depth of 130 m in the frequency range from 0.9 Hz to 11 kHz. The noise level’s variations were fairly synchronous
in a wide frequency range. Their autocorrelation interval varied from 11 to 42 h for different frequencies, and the frequency
correlation was no smaller than 0.77 within 2 decades. The integral autocorrelation interval of the wind speed’s variations
was 14.1 h. 相似文献
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Nearly transform limited picosecond pulses have been produced with a synchronously pumped cavity dumped dye laser using pyridine 1 laser dye. The observed tuning range of 678 to 790 nm extends the usefulness of cavity dumped systems pumped by mode locked argon ion lasers. Pulse autocorrelation widths as short as 3.85 ps were observed. The effects of the variation of bandwidth and net gain on autocorrelation shape and width are presented. Observed autocorrelation traces are compared to transform limited autocorrelation traces calculated from the corresponding power spectra. 相似文献
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A memory-function model is used to compute the velocity autocorrelation function and the self-diffusion coefficient of a dense Lennard-Jones fluid from the zero-time correlation functions of the molecular velocity and its first two time derivatives. It is shown that these zero-time correlation functions can be evaluated in terms of the radial distribution function and the pair potential only, i.e. without considering higher order correlation functions. Since molecular dynamics results are available for the radial distribution function as well as the velocity autocorrelation function and the self-diffusion coefficient, a rigorous test of the chosen memory function is possible. The agreement is reasonable, although generally not within the error bands of the molecular dynamics results. 相似文献
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针对大规模多输入多输出(multiple input multiple output, MIMO)系统信道估计中的导频设计问题,在压缩感知理论框架下,提出了一种基于信道重构错误率最小化的自适应自相关矩阵缩减参数导频优化算法.首先以信道重构错误率最小化为目标,推导了正交匹配追踪(orthogonal matching pursuit, OMP)算法下信道重构错误率与导频矩阵列相关性之间的关系,并得出优化导频矩阵的两点准则,即导频矩阵列相关性期望和方差最小化;然后研究了优化导频矩阵的方法,并提出相应的自适应自相关矩阵缩减参数导频矩阵优化算法,即在每次迭代过程中,以待优化矩阵平均列相关程度是否减小作为判断条件,调整自相关矩阵缩减参数值,使参数不断趋近于理论最优.仿真结果表明,与采用Gaussian矩阵、Elad方法、低幂平均列相关方法得到的导频矩阵相比,本文所提方法具有更好的列相关性,且具有更低的信道重构错误率. 相似文献