Effect of preformed plasma on terahertz-wave emission from the plasma generated by two-color laser pulses
Effect of preformed plasma on terahertz-wave emission from the plasma generated by two-color laser pulses
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DOI：
10.1103/physreva.83.023828
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发表时间：
2011-02
影响因子：
2.9
通讯作者：
Y. Minami;M. Nakajima;T. Suemoto
中科院分区：
文献类型：
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作者：
Y. Minami;M. Nakajima;T. Suemoto
在由基波和二次谐波组成的激光脉冲在空气等离子体中形成太赫兹波的过程中，在主脉冲前0-2 ns引入了一个弱的预脉冲。预脉冲抑制了主脉冲产生的太赫兹波。我们分析了抑制因子作为预脉冲和主脉冲之间的时间间隔的函数，发现来自主脉冲的太赫兹波在预脉冲之后立即减小，在几百皮秒内部分恢复，然后缓慢恢复。这种抑制归因于致密的等离子体，其吸收并屏蔽所产生的THz波，因为弛豫时间接近于来自等离子体的荧光的寿命。结果支持了等离子体电流模型解释THz波产生的主要机制的观点。
We introduced a weak prepulse 0-2 ns before the main pulse in the formation of a terahertz (THz) wave in air plasma by laser pulses composed of fundamental and second-harmonic waves. The prepulse suppressed the THz wave generated by the main pulse. We analyzed the suppression factor as a function of the time interval between the prepulse and the main pulse and found that the THz wave from the main pulse decreases immediately after the prepulse, recovers partially within several hundred picoseconds, and then recovers slowly. This suppression is attributed to the dense plasma, which absorbs and screens the generated THz wave, since the relaxation time is close to the lifetime of the fluorescence from the plasma. The results support the idea that the major mechanism of THz wave generation is explained by the plasma current model.