超短啁啾脉冲光束空间奇异性的形成与消除

研究了超短啁啾脉冲光束在真空中的传输行为以及在传输过程中时空奇异性的形成. 结果表 明，对于脉冲时间较长（相对于一个光学周期）的超短啁啾脉冲光束，啁啾导致的脉冲光谱 展宽仍然会导致脉冲光束空间奇异性的出现. 脉冲啁啾比脉冲长度对脉冲光束空间奇异性的 出现影响更大. 给出了超短啁啾高斯脉冲光束在不同参数下的数值模拟、空间奇异性出现的 条件等，并用复解析信号理论消除了空间奇异性的出现. 关键词： 单周期 缓变包络近似 奇异性 啁啾脉冲

The production and elimination of the spatial singularity for ultrashort chirp ed pulse-beam propagation in free space

We study the propagation of ultrashort chirped pulsed beams in free space. We find that the slowly-varying envelope approximation and complex amplitude envelope are not suitable for ultrashort chirped pulsed beams anymore, because they lead to the spatial singularity that is inconsistent with the physical significanc e of the beam propagation. And the chirp influences the spatial singularity mor e seriously than the width of the pulsed beam does. The spatial singularity can be eliminated by using the complex analytical signal theory. In this paper, we g ive the simulations of spatial singularity about ultrashort chirped pulsed Gauss ian beams with a series of parameters, and the conditions that lead to the spati al singularity etc. We think that the broad spectrum of the ultrashort pulsed be am is the original reason for the spatial singularity.