1 贵州大学物理学院，贵州 贵阳 550025
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和超强激光科学卓越创新中心，上海 201800
3 中国科学院大学材料科学与光电子工程中心，北京 100049
基于光电流模型，通过数值模拟和理论分析，研究了静电场幅值对飞秒激光气体微等离子体中太赫兹辐射的影响。结果显示，随着外加静电场幅值的增大，太赫兹辐射的强度呈线性增大；当外加电场极性相反时，太赫兹波形整体反转；当外加电场与线偏振激发激光的偏振方向呈一定夹角时，太赫兹辐射的偏振方向完全由外加电场方向决定。数值模拟结果与已有的实验结果相符。理论分析表明，这个线性依赖、极性反转以及夹角依赖均源于等离子体产生之后的静电加速的主导作用。
激光光学 超快激光 激光成丝 太赫兹辐射 静电场 数值模拟 中国激光
2022, 49(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, 北京 100049
3 淮阴工学院数理学院, 江苏 淮安 223001
在充分考虑测量仪器特点的基础上设计非方形迹图,具体对原方形迹图进行如下三种操作:频率轴的低通滤波,降低非线性过程中相位匹配带宽的要求;频率轴的上采样,充分利用光谱仪的高分辨率;延时轴的下采样,明显减少测量耗时并提高精度。由此基于层叠成像算法对二次谐波、偏振门和交叉相位调制三种构型的频率分辨光学开关(FROG)使用非方形迹图进行脉冲重建并对重建能力进行比较,发现在频率轴“1/3×”低通滤波和“4×”上采样的情况下,交叉相位调制构型能够在仅使用8个延时(原方形迹图需128个)的情况下成功实现脉冲的重建。因延时操作为FROG技术中最耗时的环节之一,减少其次数可有效促进FROG用于超短激光脉冲的实时测量。
测量 超短脉冲表征 频率分辨光学开关 光束构型 非方形迹图
1 上海大学理学院物理系, 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和超强激光科学卓越中心, 上海 201800
3 中国科学院上海光学精密机械研究所量子光学重点实验室, 上海 201800
针对存在增益损耗的三能级非厄米量子系统,提出了一种新型的非厄米受激拉曼绝热捷径(NH-STIRSAP)技术。该技术基于传统的受激拉曼绝热通道(STIRAP),通过灵活调控系统的非厄米项,使系统演化中的非绝热耦合得到有效抵消,从而加速绝热演化过程。详细的数值计算和理论分析结果证实,基于所提技术,系统的绝热演化速度快,且制备的量子态具有高保真度。并展示了所提技术在量子分束方面的应用。与传统绝热捷径技术相比,NH-STIRSAP新技术具有更广泛的应用。
量子光学 受激拉曼绝热通道 非厄米系统 绝热捷径 量子分束
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和超强激光科学卓越中心, 上海 201800
2 中国科学院大学, 北京 100049
阿秒瞬态吸收(Attosecond Transient Absorption, ATA)谱是一种非常有用的研究原子分子中亚飞秒时间尺度超快动力学的技术。通过数值求解含时薛定谔方程,模拟了氢分子离子( H2+)在近红外(NIR)和深紫外(XUV)强复合激光场中的演化,对比了 H2+在核动和不动两种情形下ATA谱的异同。研究结果显示,当核不动时,所得的ATA谱与原子下的结构类似;当核动时,ATA谱呈现出丰富的周期调制的吸收线结构,而且其调制周期恰好等于NIR光周期的一半。通过分析 H2+的电离解离特性,证实了该半周期调制是源于 H2+基态和激发态的不同量子跃迁路径间的干涉。对比两种情形下的ATA谱,可以看出核运动对分子ATA谱的显著影响。
超快光学 瞬态吸收谱 阿秒脉冲 含时薛定谔方程 半周期调制
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
3 淮阴工学院数理学院, 江苏 淮安 223001
利用频率分辨光学开关(FROG)法测量超短激光脉冲时,使用层叠成像算法能够实现脉冲的超分辨重建。将FROG法测量的迹图在频域中以矩阵形式表达,结合sinc函数在频率轴的延展性质,成功诠释了FROG法的相位编码原理,该分析为超短脉冲的超分辨恢复提供了理论支持。在此基础上,数值仿真演示了对FROG迹图的频率轴和延时轴同时进行欠采样的情形下,利用层叠成像算法实现的相位恢复结果。该结果有助于指导FROG的测量,提高测量的精度,减少测量时间。
激光光学 超短脉冲表征 相位编码 频率分辨光学开关 层叠成像算法
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 100039
3 上海师范大学数理学院, 上海 200234
用无退相干子空间的方法抑制集体退相干,实现不受比特反转错 误影响的通用量子计算。 该方案基于腔电动力学系统,用囚禁于腔中的2个相邻原子编码1个逻辑比特,构造出抑制集体比特 反转错误的4维无退相干子空间。通过调节外加光场与腔的耦合,在无退相干子空间中完成了2个非 对易的单比特操作和控制相位门,实现了克服集体比特反转错误的通用量子计算。
量子光学 通用量子计算 无退相干子空间 比特反转错误 quantum optics universal quantum computation decoherence-free subspace bit-flip error
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 University of Chinese Academy of Sciences, Beijing 100039, China
3 Department of Physics, Shanghai Normal University, Shanghai 200234, China
We investigate the reflected field for few-cycle ultra-short laser pulses propagating through resonant media embedded within wavelength-scale structures. Full-wave Maxwell–Bloch equations are solved numerically by using the finite-difference time-domain method. The results show that the spectral feature of the reflected spectrum is determined by the Bragg reflection condition, and that the periodic structure of a dense atomic system can be regarded as a one-dimensional photonic crystal and even as a highly reflective multilayer film. Our study explains the suppression of the frequency shifts in the reflected spectrum based on the Bragg reflection theory and provides a method to control the frequency and frequency intervals of the spectral spikes in the reflected spectrum.
320.2250 Femtosecond phenomena 320.7150 Ultrafast spectroscopy 020.1335 Atom optics Chinese Optics Letters
2015, 13(12): 123201
Author Affiliations
Abstract
State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800
We propose two schemes of atom localization based on the interference of double-dark resonances in a tripod and a 'Lambda'-type four-level system. It is demonstrated that the localization is significantly improved owing to the interference of double-dark resonances. In the tripod scheme, the localization can be manipulated by the parameters of an additional control field. Via adjusting the Rabi frequency of the field, one can double the probability of detecting the atom within subwavelength domain. By decreasing the detuning of the field, higher spatial resolution can be achieved. In the 'Lambda'-type four-level system, via adjusting the probe field detuning, we can not only make the atom localized at the nodes of the standing-wave field with high precision, but also increase the detecting probability of the atom at a particular position by a factor of 2.
270.0270 Quantum optics 270.1670 Coherent optical effects Chinese Optics Letters
2007, 5(s1): 268
Author Affiliations
Abstract
State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800
The effects of vacuum-induced coherence (VIC) on the properties of the absorption and gain of the probe field in an equispaced three-level ladder atomic system are investigated. It is found that lasing without inversion (LWI) is remarkably enhanced due to the effect of VIC in the case of the small incoherent pump rate.
270.0270 quantum optics 270.1670 coherent optical effects Chinese Optics Letters
2005, 3(5): 05308
Author Affiliations
Abstract
1 Physics Department, Shandong Normal University, Ji'nan 250014
2 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800
It is shown that in an open V-type atomic system without incoherent pumping, the spontaneously generated coherence (SGC) can not only lead to lasing with inversion but also lead to lasing without inversion (LWI) including at resonance of the driving and probe fields. This conclusion is much different from that obtained in the corresponding closed V-type system.
270.1670 coherent optical effects 270.3430 laser theory Chinese Optics Letters
2004, 2(12): 12725
