共查询到19条相似文献,搜索用时 89 毫秒
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等衍射长度超短脉冲贝塞耳-高斯光束的传输特性 总被引:8,自引:8,他引:0
使用复解析信号法,研究了衍射长度与频率无关的超短脉冲贝塞耳-高斯光束在自由空间中的传输,推导出了解析表达式并进行了理论和计算分析.结果表明:在无衍射长度内,等衍射长度超短脉冲贝塞耳.高斯光束的横向光强分布扩展很小.在无衍射长度之外,横向光强分布有显著扩展.但是,在无衍射长度内轴上脉冲波形仍有展宽.随传输距离增加轴上蓝移单调增加逐渐达到一渐近值.随横向距离增加轴外光谱移动由蓝移变为红移. 相似文献
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超短脉冲贝塞尔-高斯光束在自由空间的传输特性 总被引:3,自引:0,他引:3
使用复解析信号法研究了束宽与频率无关的超短脉冲贝塞尔-高斯光束在自由空间的传输特性。研究表明:在无衍射长度内,超短脉冲贝塞尔-高斯光束的横向光强分布几乎不变并集中在传输轴附近,轴上脉冲随传输距离增加而展宽。在无衍射长度外,横向光强分布显著扩展。随传输距离增加,轴上光谱蓝移先增加,达到极大值后逐渐减小,最后在远场趋于一渐近值。对单周期的超短脉冲贝塞尔-高斯光束的轴上光谱蓝移先增加,达到极大值0.50 fs-1。然后逐渐减小,在远场蓝移趋于渐近值0.16 fs-1。 相似文献
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超短脉冲高斯光束在线性色散介质中的远场特性 总被引:12,自引:12,他引:0
基于瑞利-索末菲衍射积分公式,在未作近轴近似的条件下,推导出等束宽超短脉冲高斯光束通过线性色散介质的远场公式,并用于研究其远场特性,所得公式可用于大衍射角情况.结果表明,等束宽脉冲高斯光束的频谱上存在一临界角,小于临界角时,出现蓝移;大于临界角时,出现红移,红移量随着衍射角的增大而增大.而脉冲波形将经历时间移动,移动量随衍射角的增大而增大;远场高斯脉冲波形将不再保持不变.此外,群速度色散将引起啁啾,啁啾量随衍射角的增大而减小. 相似文献
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给出了自由空间中超短辛格高斯脉冲光束在频率域传输的方程.对超短辛格高斯脉冲光束的功率谱进行了研究.结果表明:超短辛格高斯脉冲光束的轴外频谱具有红移、频谱变窄等性质.超短辛格高斯脉冲光束的光谱在衍射角不为零时有红移现象,并且随着衍射角的增加光谱红移也逐渐增大,频谱宽度逐渐变窄.在十倍瑞利距离处的数值模拟结果表明,衍射角等于3°时的频谱宽度仅为衍射角为0°时频谱宽度的四分之一. 相似文献
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从平面波的角谱表示出发,研究了超短光脉冲通过分层介质的远场频谱特性作为一个例子,对飞秒高斯脉冲光束通过位于自由空间中均匀介质薄膜的远场透射谱进行了分析讨论,数值计算结果显示远场谱明显不同于入射光场谱分布,在不同的观察方向上可呈现谱线变窄、红移、蓝移以及分裂成双重谱线的现象频移量的大小和谱分布形式与介质参量以及脉冲的谱线宽度、有效空间宽度和观察方向有关. 相似文献
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超短脉冲高斯光束通过透镜的聚焦特性 总被引:1,自引:4,他引:1
利用傅里叶积分变换法研究了超短脉冲高斯光束通过透镜的聚焦特性,给出了透镜焦平面上光强的空间、时间分布,以及能量密度分布。在所用数学处理中未使用缓变包络近似,结果对于包括单周期超短脉冲情况都是成立的。数值计算结果和物理分析表明,不考虑色散时,焦点附近的脉冲宽度相对于初始脉冲几乎不变。对于色散透镜,研究了透镜色差和群速度色散影响。透镜色差使焦点附近的脉冲(特别是脉冲前沿)显著展宽,能量密度分布展宽,峰值功率降低。群速度色散会进一步使脉冲展宽,脉冲前沿出现振荡,峰值功率降低,但它对脉冲光束的能量密度分布影响很小。更高阶的色散效应影响较小。 相似文献
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Based on the Rayleigh diffraction integral and complex analytical signal representation, the strict propagation expression and its Fourier spectrum for ultrashort pulsed Gaussian beams with constant waist width are derived, which have the general applicable advantage, because the paraxial approximation, pulsed envelope representation and far-field approximation are not invoked. The far-field and paraxial expressions are obtained as the special cases of our general results. Numerical calculation results are given to illustrate the spatiotemporal propagation properties of few- and single-cycle pulsed Gaussian beams with constant waist width. A comparison with the paraxial results and previous work is also made. 相似文献
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Based on the Rayleigh diffraction integral and complex analytical signal representation, the free-space analytical propagation equation and its Fourier spectrum for ultrashort chirped pulsed Gaussian beams with constant diffraction length are derived. The effect of chirp parameter on the spatiotemporal and spectral properties is illustrated with analytical formulas and numerical calculation results. It is shown that the axial spectra of ultrashort chirped pulsed Gaussian beams become broadened with increasing chirp parameter. For single optical cycle, the transversal intensity distribution is affected by increasing chirp parameter, but almost not affected for several optical cycles. Moreover, the positive or negative sign of the chirp parameter has no effect on the spectral distribution and intensity distribution. 相似文献
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在Lax等建立的微扰法的基础上,应用傅里叶变换的方法得到了一种用于自由空间中单周期以上(即脉冲长度在一个振荡周期以上)脉冲光束的矢量非傍轴修正方法.在频域,其横向分量的一阶修正等价于Fu等所得相应结果,而在时域内则比Fu等所得结果更有利于非傍轴解析解的得出.通过量级关系证明了矢量效应在对标量傍轴光束修正中的必要性.从例子中发现,由于时空耦合的存在,超短脉冲光束中的矢量非傍轴效应会被其时间分布所影响.
关键词:
矢量
非傍轴
超短脉冲光束 相似文献
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Starting from the Rayleigh diffraction integral, the propagation equation of ultrashort pulsed beams in dispersive media is derived without making the paraxial approximation and slowly varying envelope approximation (SVEA). The spatiotemporal properties of ultrashort pulsed beams in dispersive media, such as spectrum redshifting, narrowing and pulse distortion are illustrated with pulsed Gaussian beams. It is stressed that the “antibeam“ behaviour of ultrashort pulsed beams can be avoided, if a suitable truncation function is chosen. 相似文献
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Under the condition that the propagation constant k in dispersive media should be larger than zero, a simple method is proposed to eliminate the spatial singularity of ultrashort pulsed beams propagating in dispersive media. Taking the pulsed Gaussian beam (PGB) as a typical example, the analytical propagation equation in the space–time domain is derived and the spatiotemporal propagation properties of PGBs in normal and anomalous dispersive media are discussed both analytically and numerically. The physical explanation of the results is presented. 相似文献
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Based on the Fourier transform method, a simple closed-form expression for the on-axis power spectrum of ultrashort Gaussian pulsed beams in diffraction at a circular aperture is derived, which permits us to study spectral changes both analytically and numerically. It is shown that for diffracted pulsed beams there exist spectral red and blue shifts, spectral narrowing, and spectral switches in the near field. The aperture diffraction plays an important role in spectral switching, but both the truncation parameter and bandwidth (or equally, Fourier transform limited pulse duration) affect the behavior of spectral switches. 相似文献
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从超短脉冲光束的傍轴传输方程出发,得出了描述任意脉冲形式驱动的等衍射超短脉冲厄米高斯光束在自由空间中的解析表达式. 并通过例子研究了超短脉冲厄米高斯光束的传输性质. 结果表明:在传输过程中,由于群速度的空间分布不均匀性,会导致超短脉冲光束的脉冲时间延迟,并进而导致了在脉冲不同位置处光束横向分布严重偏离了厄米高斯函数. 另外,在传输过程中,发现不同阶数的脉冲厄米高斯光束会发生不同次数的极化反转. 并用脉冲光束的群-相速度差对这一现象进行了解释.
关键词:
超短脉冲
厄米高斯光束 相似文献