科学家对单层石墨烯产生的可调谐太赫兹辐射进行优化和系统分析-凯发k8旗舰厅

       近日，南京理工大学的金成与西北师范大学的周效信以及西北民族大学的李小勇合作，并取得一项新进展。经过不懈努力，他们利用不同持续时间的双色激光脉冲对单层石墨烯产生的可调谐太赫兹辐射进行优化和系统分析。相关研究成果已于2023年8月21日在国际知名学术期刊《物理评论a》上发表。

　　该研究团队通过优化双色激光脉冲，发现可以在法向入射时从单层石墨烯有效产生频率可调的太赫兹(thz)辐射。研究人员针对三种不同的脉冲持续时间，应用遗传算法寻找具有不同特性的最优激光参数。研究发现，所产生的太赫兹光谱具有不同的光谱形状，其对两种颜色之间相对相位的依赖随脉冲持续时间的变化而显著变化。为了解释三个持续时间的太赫兹辐射，研究人员建立了一个干涉模型。他们采用四波混合模型来获得长持续时间的最优第二色波长，并使用不对称参数模型来描述相对相位在短持续时间内的太赫兹产额。

　　研究人员发现，随着双色激光脉冲的持续时间增加，太赫兹产生的主要机制从激光脉冲的对称性转变为四波混频。此外，他们还发现，较短的脉冲持续时间更适合产生高强度的太赫兹辐射，而较长的持续时间更适合用于选择太赫兹频率。为了最大限度地利用遗传算法（ga）来最大化间隙石墨烯的太赫兹辐射，他们优化了双色激光的参数。最后，他们通过改变双色激光脉冲的参数来研究时域太赫兹波形的变化。

附：英文原文

title: optimal generation and systematic analysis of tunable terahertz emissions from single-layer graphene using two-color laser pulses with different durations

author: zhong guan, zhiming yin, jiahao you, bincheng wang, xiaoyong li, guo-li wang, xiao-xin zhou, cheng jin

issue&volume: 2023/08/21

abstract: we propose that frequency-tunable terahertz (thz) emissions can be efficiently generated from single-layer graphene at normal incidence by optimizing two-color laser pulses. for three different pulse durations, a genetic algorithm (ga) is applied to search for optimal laser parameters, which show quite different characteristics. resulted thz spectra have different spectral shapes, and their dependence on the relative phase between two colors is dramatically changed with pulse duration. we develop an interference model to explain the thz emissions for three durations, employ a four-wave mixing model to obtain the optimal wavelength of second color for long duration, and use an asymmetry parameter model to describe the thz yields with the relative phase for short duration. we reveal that the dominant mechanism for the thz generation is shifted from the symmetry of laser pulse to the four-wave mixing when the duration of two-color laser is increased. we identify that the shorter duration is better for generating intense thz emission while the longer duration is preferable for selecting the thz frequency. furthermore, we optimize the two-color laser parameters for maximizing the thz emissions from gapped graphene with the ga. and we also examine the temporal thz waveforms by varying the parameters in the two-color laser pulses.

doi: 10.1103/physreva.108.023515

source: https://journals.aps.org/pra/abstract/10.1103/physreva.108.023515