【摘要】 对超强飞秒激光在空气中传输形成等离子体通道进行了系统研究。空气中长等离子体通道的形成主要是由于光学克尔自聚焦效应,等离子体散焦作用和光束衍射之间达到了动态平衡,使超强飞秒激光脉冲在空气中形成数百米长甚至千米量级长度的等离子体通道。我们发展了通道的四种主要诊断方法:声学诊断、荧光探测、电阻率测量和横截面成像方法,这几种方法各有优势,可以互为补充．研究了通道同时伴随的三次谐波辐射,三次谐波具有与基频激光相似的变化规律。从应用角度出发,我们对通道内细丝进行了优化控制,对通道寿命的延长进行了研究,使通道寿命达到了微秒量级。改变激光脉冲的初始啁啾,得到了更远距离处的稳定成丝分布,和最优化的超连续光谱产生,此外,还介绍了激光诱导高压放电的应用研究。更多还原

【Abstract】 Recent investigations carried out at the Laboratory of Optical Physics, Institute of Physics, CAS, on the propagation of intense femtosecond laser pulses in air is presented. A long-distance plasma channel is formed with a length of several hundreds meters. Four methods are developed to diagnose the plasma channel. Strong third harmonic emission is observed with a maximum conversion efficiency of 0.3%. The filaments distribution is optimized for applications using a pinhole with different diameters. The lifetime of the plasma channel is prolonged up to the order of microsecond. The filamentation process and the surpercontinuum emission are closely related with the initial chirp of the laser pulse. Triggering and guiding of large gap discharges in air by plasma channels opens promising perspectives for lightning control.更多还原