Two-color strong-field terahertz amplification in the non-identical focusing condition

IF 3.5 2区物理与天体物理 Q2 PHYSICS, APPLIED

Applied Physics Letters Pub Date : 2025-01-02 DOI:10.1063/5.0246226

Jingjing Zhao, Yizhu Zhang, Yanjun Gao, Ahai Chen, Yuhai Jiang

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引用次数: 0

Abstract

High optical-to-terahertz (THz) conversion efficiency is crucial for generating THz waves. Strong-field ionization using a bi-focal bi-chromatic geometry produces cascading plasmas, leading to amplified THz generation and extended THz bandwidth. We investigate the effect of focal length in this bi-focal geometry on THz intensity. The results show that the THz intensity produced with non-identical focal lengths of the bi-chromatic fields is 25% higher than that of identical focal lengths, and 15 times higher than traditional bi-chromatic THz generation. The electro-optic sampling measurements reveal that the THz-electric-field intensity generated by the bi-focal bi-chromatic field exhibits periodic oscillations, which results from the modulation of the photoelectron's asymptotic velocity by the relative phase of the bi-chromatic pulses, and are consistent with the photocurrent model. The photocurrent simulations indicate that the self-compression of the second harmonic pulse significantly enhances THz amplification and extends the THz bandwidth. These findings deepen understanding of the THz generation mechanism and suggest potential avenues for optimizing THz sources.

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非相同聚焦条件下的双色强场太赫兹放大

高光-太赫兹（THz）转换效率是产生太赫兹波的关键。使用双焦双色几何结构的强场电离产生级联等离子体，导致放大太赫兹产生和扩展太赫兹带宽。我们研究了这种双焦几何结构中焦距对太赫兹强度的影响。结果表明，非等距双色场产生的太赫兹强度比等距双色场产生的太赫兹强度高25%，比传统双色场产生的太赫兹强度高15倍。电光采样测量结果表明，双焦双色场产生的太赫兹电场强度表现出周期性振荡，这是由于双色脉冲的相对相位调制了光电子的渐近速度，与光电流模型一致。光电流模拟表明，二次谐波脉冲的自压缩显著提高了太赫兹放大，延长了太赫兹带宽。这些发现加深了对太赫兹产生机制的理解，并提出了优化太赫兹源的潜在途径。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Applied Physics Letters 物理-物理：应用

CiteScore

6.40

自引率

10.00%

发文量

1821

审稿时长

1.6 months

期刊介绍： Applied Physics Letters (APL) features concise, up-to-date reports on significant new findings in applied physics. Emphasizing rapid dissemination of key data and new physical insights, APL offers prompt publication of new experimental and theoretical papers reporting applications of physics phenomena to all branches of science, engineering, and modern technology. In addition to regular articles, the journal also publishes invited Fast Track, Perspectives, and in-depth Editorials which report on cutting-edge areas in applied physics. APL Perspectives are forward-looking invited letters which highlight recent developments or discoveries. Emphasis is placed on very recent developments, potentially disruptive technologies, open questions and possible solutions. They also include a mini-roadmap detailing where the community should direct efforts in order for the phenomena to be viable for application and the challenges associated with meeting that performance threshold. Perspectives are characterized by personal viewpoints and opinions of recognized experts in the field. Fast Track articles are invited original research articles that report results that are particularly novel and important or provide a significant advancement in an emerging field. Because of the urgency and scientific importance of the work, the peer review process is accelerated. If, during the review process, it becomes apparent that the paper does not meet the Fast Track criterion, it is returned to a normal track.