【摘要】 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 .更多还原

【Abstract】 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 significance of the beam propagation. And the chirp influences the spatial singularity more 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 give the simulations of spatial singularity about ultrashort chirped pulsed Gaussian beams with a series of parameters, and the conditions that lead to the spatial singularity etc. We think that the broad spectrum of the ultrashort pulsed beam is the original reason for the spatial singularity.更多还原