Shockwave-based THz emission in air
Shockwave-based THz emission in air
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DOI：
10.1364/oe.478610
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发表时间：
2023-02-13
期刊：
影响因子：
3.8
通讯作者：
Hatanaka, Koji
中科院分区：
文献类型：
--
作者：
Huang, Hsin-hui;Nagashima, Takeshi;Hatanaka, Koji
利用偏振敏感THz时域光谱和时间分辨成像技术研究了一对具有纳秒级时延和微米级空间偏移的紧聚焦飞秒激光脉冲（800nm，35fs）照射下空气中的THz辐射。预脉冲辐照在其焦点处引起空气击穿，导致冲击波阵面向外扩展。当主脉冲以纳秒级延迟照射远离预脉冲焦点的冲击波阵面时，THz辐射强度增强了近13倍，其线偏振方向沿着与冲击波阵面扩展方向平行的预脉冲和主脉冲焦点位置之间的直线。由预脉冲辐射制备的冲击波阵面的非对称密度分布定义了太赫兹辐射的偏振。从电子扩散的角度讨论了这种不对称密度分布的机制。(c)2023 Optica出版集团根据Optica开放获取出版协议的条款
THz emission in air under the irradiation of a pair of tightly-focused femtosecond laser pulses (800nm, 35fs) with nanosecond time delay and micro-meter spatial offsets is studied with polarization-sensitive THz time-domain spectroscopy and time-resolved imaging. The pre-pulse irradiation induces air-breakdown at its focus, which results in the expansion of shockwave front traveling outward. When the main pulse irradiates such shockwave front far from the pre-pulse focus with nanosecond delay, THz emission intensity was enhanced up to similar to 13-times and its linear polarization was aligned along the line between the two focus positions of the pre-and the main pulses which is parallel to the expansion direction of the shockwave front. Asymmetric density profiles of the shockwave fronts prepared by the pre-pulse irradiation define the polarization of THz emission. Mechanisms are discussed from the viewpoint of electron diffusion in such asymmetric density profiles. (c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement