1 上海大学物理系，上海 200444
2 中国科学院上海光学精密机械研究所强场激光物理国家重点实验室，上海 201800
3 中国科学院大学材料科学与光电工程中心，北京 100049
通过求解长度规范下的半导体布洛赫方程，分析了液态水在双色场驱动下发射高次谐波光谱的特征。研究表明，通过调节双色场中基频和倍频脉冲的相对相位，高次谐波光谱呈现出周期性调制的特征。在一个调制周期内，奇次谐波会随着相对相位的增加发生红移，而产率先增大后减小。时域分析结果表明，光谱移动源于正负半周期之间发射高次谐波频谱的干涉效应。
物理光学 高次谐波 双色激光场 光谱红移 频谱干涉 光学学报
2023, 43(13): 1326002
1 State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-Intense Laser Science, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
3 Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
4 Department of Physics, Shanghai University, Shanghai 200444, China
5 School of Physics and Electronic Engineering, Xinxiang University, Xinxiang 453003, Henan, China
We investigate off-axis phase-matched terahertz (THz) radiation in laser plasma pumped by few-cycle laser pulses. We find that the THz amplitude and angular distributions in the far field are sensitively dependent on the pump pulse's focal carrier-envelope phase (CEP). Ring-like profiles of THz radiation are obtained at CEP values of 0.5 π and 1.5 π, due to the inversely symmetric local THz waveforms emitted before and after laser focus. Off-axis phase-matched THz radiation offers a tool to accurately measure the CEP of few-cycle pulses at the center of a medium.We investigate off-axis phase-matched terahertz (THz) radiation in laser plasma pumped by few-cycle laser pulses. We find that the THz amplitude and angular distributions in the far field are sensitively dependent on the pump pulse's focal carrier-envelope phase (CEP). Ring-like profiles of THz radiation are obtained at CEP values of 0.5 π and 1.5 π, due to the inversely symmetric local THz waveforms emitted before and after laser focus. Off-axis phase-matched THz radiation offers a tool to accurately measure the CEP of few-cycle pulses at the center of a medium.
terahertz radiation carrier-envelope phase laser plasma off-axis phase-matching 激光与光电子学进展
2023, 60(7): 0736001
Author Affiliations
Abstract
1 State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
3 School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
4 Physics and Electronic Engineering Department, Xinxiang University, Xinxiang 453003, China
We demonstrated a scheme to differentiate the high-harmonic generation (HHG) originating from the surface states and bulk states of the topological insulator . By adopting two-color mid-infrared laser fields on , we found that the nonlinear response sensitively depends on the relative phase of the driving fields. The even harmonics arise from the surface states with a clear signature, whose modulation period equals the cycle of the second-harmonic generation (SHG) field. We reveal that the weak SHG perturbs the nontrivial dipole phase of the electron-hole pair in surface states, and thus leads to the modulation of HHG. It provides a means to manipulate the ultrafast dynamics in surface states through adopting a weak perturbing laser field.
high-harmonic generation topological insulators two-color laser fields Chinese Optics Letters
2023, 21(4): 043801
Author Affiliations
Abstract
1 State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-Intense Laser Science, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
We present a velocity-gauge model for the generation of even-order high harmonics, and reveal that the even-order harmonics originate from the multiple-step transitions among the energy bands in momentum space, while the odd-order harmonics are mainly from direct transitions. The lower valence band is found vital for the generation of even harmonics. Relative intensity of even-order harmonics versus the odd orders is calculated and shows a growing trend as the laser field amplitude increases.
solid high-harmonic generation inversion asymmetry even-order harmonics Chinese Optics Letters
2021, 19(4): 043201
1 中国科学院上海光学精密机械研究所强场激光物理国家重点实验室, 上海 201800
2 中国科学院大学材料与光电研究中心, 北京 100049
利用超强超短激光光源中激光-等离子体的相互作用,能够产生毫焦耳量级高能量的太赫兹辐射,而这种条件下产生的太赫兹辐射通常是单发的。针对该类型太赫兹辐射提出一种单发测量方案:将太赫兹波分束,用两套独立校准的啁啾脉冲光谱编码探测装置,分别同时测量太赫兹电场在水平和竖直方向上的分量,最终得到太赫兹电场的偏振态。基于所提方案进行了实验验证,用单发测量原理得到了太赫兹辐射的偏振态。实验测得的椭偏度与模型分析吻合,验证了所提单发测量方案的可行性,为单发椭偏太赫兹辐射偏振态的测量研究提供了新思路。
超快光学 太赫兹辐射 单发探测 偏振态 啁啾脉冲 中国激光
2019, 46(11): 1114001
1 中国科学院上海光学精密机械研究所强场激光物理国家重点实验室, 上海 201800
2 中国科学院大学材料与光电研究中心, 北京 100049
随着大功率激光技术的发展,由其驱动产生的太赫兹辐射受到了广泛关注。然而,大功率激光装置的重复频率低,测量其产生的太赫兹辐射的难度较大。采用时域光谱单发探测技术可以克服这一探测难点,通过单次测量就能得到太赫兹辐射的电场波形信息。回顾了太赫兹辐射时域光谱单发探测的相关研究工作进展。根据频率-时间编码和空间-时间编码两种不同的原理,详细介绍了啁啾脉冲光谱编码探测和空间-时间编码探测等测量技术,并对各个测量技术的特点和参数进行了对比,最后对太赫兹辐射的单发探测作了总结和展望。
太赫兹技术 太赫兹辐射 太赫兹波探测 超快激光技术 光谱编码 空间编码
1 中国科学院上海光学精密机械研究所强场激光物理国家重点实验室, 上海 201800
2 中国科学院大学, 北京 100049
在短丝条件下, 激光与喷气靶产生的介质相互作用, 可产生局部高密度等离子体, 在较短距离内实现双色场相位差的剧烈变化, 容易得到椭圆偏振的太赫兹(THz)辐射。通过调节气体背压, 产生了椭偏度为0.438的THz辐射。利用瞬态光电流模型对实验结果进行模拟, 所得结果和实验结果基本一致, 揭示了光电流和等离子体色散共同作用的机理。
物理光学 强场激光物理 太赫兹波 气体等离子体 椭圆偏振
Author Affiliations
Abstract
1 State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240, China
We experimentally investigate the evolution of the terahertz (THz) waveform and polarization state inside the plasma filament produced by orthogonally polarized two-color pulses. We find that the variation of the THz polarization state along the plasma column is dominantly caused by the relative phase difference and spectra blue shift of the two-color field. Elliptically polarized THz radiation is generated by controlling the initial relative phase and the filament length. The result indicates the coherent control of the polarization state of the THz emission.
040.2235 Far infrared or terahertz 260.5210 Photoionization 320.7110 Ultrafast nonlinear optics 350.5400 Plasmas Chinese Optics Letters
2016, 14(9): 093201
Author Affiliations
Abstract
The evolution of terahertz (THz) waveform in air plasma driven by low-energy few-cycle laser pulses is investigated to improve the accuracy of the carrier envelope phase (CEP) determination. Based on the transient photocurrent model, a balanced spatial distribution of the Kerr and free-electron effects in the plasma is found at 109 \mu J input energy. THz inversion occurs only once at the initial CEP of 0.5\pi, in which high-precision measurement of the CEP of few-cycle laser pulses is achieved.
300.6495 Spectroscopy, teraherz 140.7090 Ultrafast lasers 260.3060 Infrared 350.5400 Plasmas Chinese Optics Letters
2013, 11(12): 123002
1 中国科学院上海光学精密机械研究所强场激光物理国家重点实验室, 上海 201800
2 同济大学物理系, 上海 200092
超短激光脉冲驱动等离子体光丝产生太赫兹辐射的研究对于揭示太赫兹产生的微观机理以及太赫兹源的发展和应用有重要的基础意义。系统介绍了包括载波包络稳定的红外周期量级激光脉冲的产生、基于周期量级激光强场驱动等离子体光丝产生太赫兹辐射的机理、等离子体光丝中周期量级光场的传输、波形可控太赫兹辐射的产生及其在载波包络相位测量技术上的应用等方面的最新进展。
非线性光学 等离子体 太赫兹辐射 周期量级脉冲 载波包络相位 激光与光电子学进展
2013, 50(8): 080004
