| 引用本文格式: Lu Jun-Chen,Zhang Jia-Ning,Tang Wen-Qi,Zhang Yi-Zhu. Trajectory analysis of THz waveforms detectionbased on ionisation-induced second harmonic [J]. J. At. Mol. Phys., 2026, 43: 043001 (in Chinese) [陆俊臣,张家宁,唐文琦,张逸竹. 基于电离诱导二次谐波探测THz波形的轨线分析 [J]. 原子与分子物理学报, 2026, 43(4): 043001] |
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| 基于电离诱导二次谐波探测THz波形的轨线分析 |
| Trajectory analysis of THz waveforms detectionbased on ionisation-induced second harmonic |
| 摘要点击 489 全文点击 251 投稿时间：2025-01-05 修订日期：2025-01-23 |
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| DOI编号
10.19855/j.1000-0364.2026.043001 |
| 中文关键词
光电子学，太赫兹光场探测，时域光谱，非线性效应，探测灵敏度 |
| 英文关键词
Optoelectronics, Terahertz photoionisation detection, Time-domain spectroscopy, Nonlinear effects, Detection sensitivity |
| 基金项目
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| 中文摘要
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| 太赫兹时域波形探测一直是太赫兹光场探测领域中的关键研究问题。传统的太赫兹时域 波形检测方法主要依赖光电导天线和非线性光学晶体中的电光采样技术。然而,这些方法的探测带宽较为有限,通常无法覆盖整个太赫兹频段,存在频谱响应的局限性。相比之下,基于光电离效应的太赫兹脉冲波形检测技术通过优化飞秒激光的电离窗口,缩短其持续时间至小于脉冲宽度,从而显著提升了时间分辨率,并在实验中得到验证。本文对基于光电离机制的太赫兹时域波形探测理论进行了深入分析。通过使用单原子光电流模型,利用飞秒激光电离气相介质产生的二次谐波与太赫兹脉冲呈现正相关的特性,研究单一电离事件及其相干叠加效应,进一步阐明了相干太赫兹时域光场探测的理论基础。此外,利用轨线分析方法,揭示了等离子体不对称性形成的主要因素,表明主要由不同强度的飞秒激光周期内的干涉效应不同,引发重建的太赫兹脉冲波形变化。该研究为深入理解太赫兹光电离探测方法的内在物理机制提供了新的视角。 |
| 英文摘要
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| Terahertz time-domain waveform detection has been a key research problem in the field of terahertz optical field detection. Conventional terahertz time-domain waveform detection methods mainly rely on electro-optical sampling techniques in photoconductive antennas and nonlinear optical crystals. However, the detection bandwidth of these methods is relatively limited and usually cannot cover the entire terahertz frequency band, and there is a limitation of spectral response. In contrast, the terahertz pulse waveform detection technique based on the photoionisation effect significantly improves the temporal resolution by optimising the ionisation window of the femtosecond laser and shortening its duration to less than the pulse width, which has been validated in experiments. In this paper, the theory of terahertz time-domain waveform detection based on the photoionisation mechanism is thoroughly analysed. The theoretical basis of coherent terahertz time-domain optical field detection is further elucidated by using a single-atom photocurrent model to study a single ionisation event and its coherent superposition effect by taking advantage of the positive correlation between the second harmonic generated by femtosecond laser ionisation of the gas-phase medium and the terahertz pulse. In addition, the main factors for the formation of plasma asymmetry are revealed using a trajectory analysis method, which shows that the reconstructed terahertz pulse waveform changes are mainly triggered by the different interference effects within the cycles of femtosecond lasers of different intensities. This study provides a new perspective for a deeper understanding of the intrinsic physical mechanisms of terahertz photoionisation detection methods. |
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