| 引用本文: | 沈 琦,许 虎,王九江,徐 煜,陈 曦,卢晨晖.基于光电流模型的液体介质太赫兹辐射的理论研究(J/M/D/N,J:杂志，M：书，D：论文，N：报纸).期刊名称,2024，41（3）：98-103 |
| CHEN X. Adap tive slidingmode contr ol for discrete2ti me multi2inputmulti2 out put systems[ J ]. Aut omatica, 2006, 42(6): 4272-435 |
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| 摘要: |
| 目的 超快激光作用液体介质相较于与气态、固态介质可产生更高能量的太赫兹波,相关研究工作在实验方
面已相对完善,而理论方面缺少完整解释过程,运用逐步建立瞬态光电流模型的进程详尽论述其物理机制,并通过
此模型研究水、丙酮等 4 种溶液在不同参数条件下对太赫兹的转化效率。 方法 以水分子为例,在传统光电流模型
的基础上,基于其电离原理构建三能级系统,通过水分子电离势确定电离弛豫时间,并联立分子驰豫时间与三阶非
线性极化率来确定水分子电离率及电流强度,进而构建完整的液态溶液瞬态光电流模型,并运用该模型在两束 800
nm 高斯光场下,研究了在水与丙酮等 4 种液体中不同激光参数对太赫兹辐射能量的影响。 结果 电场强度越强,导
致的分子电离率越高,对应的太赫兹转换效率也越高,并且在特定的激光强度下,最强太赫兹辐射能量对应一个最
佳脉宽及脉冲延迟,处于亚皮秒量级,此外,进一步对比了水和丙酮溶液中,太赫兹辐射的能量差异和时频谱特征,
结果表明丙酮辐射产率始终最高。 结论 在液体介质中,太赫兹辐射的能量受介质电离势、吸收系数、分子密度等多
方面影响,这也同样说明和验证了丙酮综合性能参数优于水、重水和乙醇。 利用光电流模型研究不同液态中太赫
兹辐射的强度,为理解相关更多液态介质的辐射情况以及实验提供了参考。 |
| 关键词: 太赫兹 液体介质 三能级体系 光电流模型 |
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| Theoretical Study of Terahertz Radiation in Liquid Medium Based on Photocurrent Model |
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SHEN Qi,XU Hu,WANG Jiuqiang,XU Yu,CHEN Xi,LU Chenhui
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School of Mechanical Engineering Shanghai University of Engineering Science Shanghai 201600 China
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| Abstract: |
| Objective Ultrafast lasers acting on liquid media can generate higher energy terahertz waves compared with
gaseous and solid media and the related research work has been relatively perfect in experiments while the theoretical
aspect lacks a complete explanation process. The physical mechanism of the transient photocurrent model was discussed in
detail through the process of step-by-step establishment of the model and the conversion efficiencies of four solutions
such as water and acetone to terahertz under different parameter conditions were investigated through this model.
Methods Taking water molecules as an example a three-level system was constructed based on the ionization principle on
the basis of the traditional photocurrent model. The ionization relaxation time was determined by the ionization potential of
water molecules and the ionization rate and current intensity of water molecules were determined by associating the
ionization time with the third-order nonlinear polarization rate. A complete transient photocurrent model of liquid solution
was then constructed and applied to study the effect of different laser parameters on the terahertz radiation energy in four
liquids including water and acetone under two 800 nm Gaussian light fields. Results The stronger the electric field
intensity the higher the resulting molecular ionization rate and the higher the corresponding terahertz conversion
efficiency. At a given laser intensity the strongest terahertz radiation energy corresponded to an optimal pulse width and pulse delay in the sub-picosecond order. In addition the energy difference and time-frequency spectrum characteristics of
terahertz radiation in water and acetone solutions were further compared and the results showed that the radiation yield of
acetone was always the highest. Conclusion In liquid media the energy of terahertz radiation is affected by various
aspects such as the ionization potential of the medium absorption coefficient molecular density etc. which likewise
illustrates and validates the superiority of acetone over water heavy water and ethanol in terms of the combined
performance parameters. In this paper the intensity of terahertz radiation in different liquid states is investigated using
photocurrent model which provides a reference for understanding the radiation in other liquid media as well as for
experiments. |
| Key words: terahertz liquid medium three-level system photocurrent model |
