高效高分辨率大面积透射光栅谱仪特性的理论分析

为提高透射光栅谱仪对激光等离子体Ｘ光源的收集效率的光谱分辨同铲高分辨率大面积航向光栅光谱仪。该谱仪由轮胎镜、无支撑高线密度光栅和软Ｘ光ＣＣＤ相机组成。应用部分相干光衍射理论,研究了该谱仪成偈面上的光强分布和光谱分辩率,在１．４～１２ｎｍ的摄谱范围内光 人发辨率为０．０５ｎｍ,与实验符合得很好。由于其高效率,该谱仪尤其适用于超短飞秒脉冲激光产生等离子体的实验研究。     

软X射线激光汤姆逊散射实验尝试

汤姆逊散射是诊断高温稠密等离子体状态参数的重要方法之一, 受到广泛的关注. 但是目前用于进行汤姆逊散射的探针光波长多局限于可见光或紫外光, 能够诊断的区域电子密度远低于驱动激光的临界密度. 相比较而言, 以软X射线激光作为探针, 有希望诊断更高密度区域的等离子体. 利用“神光Ⅱ”高功率激光装置产生的类氖锗软X射线激光作为探针, 开展了软X射线激光汤姆逊散射实验的尝试. 根据散射的条件, 分别进行了非相干散射和相干散射的实验, 但均未能获得明显的散射谱. 理论分析表明, 主要原因可能是实验中作为探针的类氖锗软 X射线激光的聚焦功率密度不够, 通过优化实验条件, 有希望在今后的研究中获得相干汤姆逊散射的结果. 关键词： 等离子体诊断 软X 射线激光 汤姆逊散射     

Coherent X-ray radiation generated by a relativistic electron beam in a periodic layered medium in the Bragg scattering geometry

A dynamic theory is developed for coherent X-ray radiation generated when a diverging beam of relativistic electrons crosses a periodic layered target. Expressions describing the spectral–angular characteristics of coherent X-ray radiation are obtained and analyzed in the Bragg scattering geometry.     

High resolution atomic coherent control via spectral phase manipulation of an optical frequency comb

We demonstrate high resolution coherent control of cold atomic rubidium utilizing spectral phase manipulation of a femtosecond optical frequency comb. Transient coherent accumulation is directly manifested by the enhancement of signal amplitude and spectral resolution via the pulse number. The combination of frequency comb technology and spectral phase manipulation enables coherent control techniques to enter a new regime with natural linewidth resolution.     

上海软X射线自由电子激光外种子运行模式的模拟研究

上海软X射线自由电子激光用户装置（SXFEL）是我国首台可以运行在水窗波段的自由电子激光装置,未来可以为5个实验线站供光,其主要运行模式为自放大自发辐射模式以及外种子模式。本文就SXFEL的外种子模式进行了从头到尾的模拟研究,主要包括EEHG-HGHG混合级联与单级EEHG两种方案。模拟结果表明,虽然EEHG-HGHG混合级联模式较为复杂,但能够产生更高功率的高次谐波辐射。除此之外,我们还研究了各种三维效应对EEHG的影响。模拟和分析结果表明,通过上述两种方案,采用紫外波段的种子激光,用户可以得到全相干、窄带宽、短脉冲的水窗波段自由电子激光。     

基于光子筛的软X光谱仪

 介绍了采用新型软X光谱学光子筛作为分光元件的软X光谱仪的原理和结构参数设计。新谱仪理论测量范围为100 eV~2 keV,光谱分辨力达0.35 nm。应用该谱仪在SILEX-Ⅰ装置上测量了飞秒激光与固体铜靶相互作用产生的X射线发射谱。实验结果表明,该谱仪主要性能指标达到设计要求,适合于激光与等离子体相互作用产生的软X射线研究。     

用于Z箍缩物理实验中光电管与光电倍增管相对灵敏度标定方法

软X光闪烁体功率计(闪烁体光电管系统)是阳加速器及PTS装置上进行Z箍缩实验获取软X光总辐射功率及能量等参数的主要设备,光谱响应灵敏度是这套设备最关键的物理参数。为获取闪烁体功率计系统的光谱响应灵敏度,在北京同步辐射实验室进行了闪烁体与光电倍增管系统的光谱响应灵敏度标定,而要将闪烁体与光电倍增管系统的光谱响应灵敏度转换成Z箍缩实验需要的闪烁体与光电管系统的光谱响应灵敏度,还需要进行光电管与光电倍增管相对灵敏度标定,为此研制了一套光电管与光电倍增管光谱响应灵敏度相对标定系统。应用此系统进行标定实验,得到了光电管与光电倍增管的相对灵敏度,进而推出了功率计系统的光谱响应灵敏度。     

Femtosecond strong-field coherent control of nonresonant ionization with shaped pulses

The strong-field coherent control of the nonresonant ionization of nitrous oxide using shaped pulses is investigated.We study the dependence of periodic coherent oscillation of the total ionization yield on the variation of laser phase parameters. The physical mechanism of the strong-field coherent control is investigated experimentally and theoretically by the nonresonant spectral phase interferences in the frequency domain. We show that the intense shaped pulses with broadband and off-resonance can be used as a robust strong-field coherent control method.     

Femtosecond phase-and-polarization control for background-free coherent anti-Stokes Raman spectroscopy

Phase-and-polarization coherent control is applied to control the nonlinear response of a quantum system. We use it to obtain high-resolution background-free single-pulse coherent anti-Stokes Raman spectra. The ability to control both the spectral phase and the spectral polarization enables measurement of a specific off-diagonal susceptibility tensor element while exploiting the different spectral response of the resonant Raman signal and the nonresonant background to achieve maximal background suppression.     

Quantum theory of laser cooling: Statistical description of the process dynamics

A dynamic theory of coherent X-ray radiation generated in a periodic layered medium by a relativistic electron multiply scattered by target atoms has been developed. The expressions describing the spectral–angular characteristics of parametric X-ray radiation and diffracted transition radiation are derived. Numerical calculations based on the derived expressions have been performed.     

非相干照明条件下的ptychographic iterative engine成像技术

在传统多波长相干衍射成像理论的基础上提出适用于 X-射线和电子束等非相干光源照明成像的改进多波长ptychographic iterative engine 方法, 同时将小孔形状和照明光谱信息用于叠代计算, 可以在非相干照明条件下精确重建出物体的强度透射像和相位透射像, 并对光源带宽对重建精度的影响进行了分析, 对于解决如何在非相干照明条件下对大尺寸物体进行精确相位成像的问题具有较好的科研和实用价值.     

Soft-x-ray coherent radiation using a single-cascade free-electron laser

Coherent harmonic generation using single-pass free-electron lasers is a promising method for generating coherent radiation in the vacuum ultraviolet and x-ray spectral region. We propose a simple scheme allowing one to generate powerful coherent radiation in the soft x-ray region by making use of present available technology. The method relies on the possibility of creating substantial bunching in a relativistic electron beam, while limiting the growth of its energy spread. The validity of the scheme is demonstrated using a simple one-dimensional model. Results are confirmed by three-dimensional simulations.     

Spectral anomalies and spectral switches of partially coherent and polychromatic light diffracted at an aperture

Inrecentyearsanewbranchofmodernphysicalopticscalledsingularoptics[1]hasbeendeveloped.In2002theworkinsingularopticswasextendedfrommonochromaticlighttospatiallyfullycoherentandpolychromaticlightbyGburetal.[2—4].Itwasfoundthat,whenaconverging,spatiallyfullycoherentandpolychromaticsphericalwaveisdiffractedatanaperture,anomalousspectralchangestakeplaceclosetozerosoftheintensityinthefarfield;i.e.thespectrumisredshiftedatsomepoints,blueshiftedatothers,andsplitintotwolineselsewhere.Thepredictionsofsp…     

气体靶激光等离子体软X-射线源实验研究

介绍了一种无碎屑、高亮度、高工作频率的气体靶激光等离子体软X 射线源。其喷气阀门由压电陶瓷驱动 ,工作频率可达到 40 0Hz。与金属靶激光等离子体软X 射线源相比 ,此光源无碎屑。与喷嘴由电磁阀控制的气体靶激光等离子体软X 射线源相比 ,它有较高的工作频率。一工作在模拟模式的通道电子倍增器被用于探测来自光源的软X 射线辐射 ,其输出信号经过一电荷灵敏前置放大器进一步放大变成电压脉冲信号 ,脉冲幅度与输入电荷灵敏前置放大器的电量成正比。实验测得CO2 ,Xe和Kr在 8～ 2 2nm软X 射线投影光刻常用波段的光谱辐射特性。CO2 光谱包括类锂和类铍离子跃迁形成的线谱 ,Xe光谱是多电荷氙离子 4d 5f,4d 4f,4d 6p和 4d 5p跃迁所形成的光谱。Kr气体靶光谱包括类铜离子、类镍离子、类钴离子和类铁离子跃迁形成的线谱和连续谱。     

Bright, coherent, ultrafast soft X-ray harmonics spanning the water window from a tabletop light source

We demonstrate fully phase-matched high harmonic emission spanning the water window spectral region important for nano- and bioimaging and a breadth of materials and molecular dynamics studies. We also generate the broadest bright coherent bandwidth (≈300 eV) to date from any light source, small or large, that is consistent with a single subfemtosecond burst. The harmonic photon flux at 0.5 keV is 103 higher than demonstrated previously. This work extends bright, spatially coherent, attosecond pulses into the soft x-ray region for the first time.     

软X射线测量用电阻式薄膜量热计

介绍了一种用于软X射线辐射能量测量的电阻式薄膜量热计。利用电流的欧姆热效应对薄膜量热计的灵敏度进行了标定。在有基底薄膜的标定过程中,采用一维热扩散模型,考虑了金属薄膜向基底的传导热损失。利用电阻式薄膜量热计对聚龙一号装置钨丝阵Z箍缩产生的软X射线进行了测量,并与平响应X射线二极管(XRD)探测器的测量结果进行了比较。实验结果表明,电阻式薄膜量热计测量的软X射线辐射能量和辐射功率与平响应XRD探测器结果在测量不确定度范围内合理地一致。     

选频元件对光纤激光器自组织相干合成的影响

采用不同中心谱线、不同谱线宽度的选频元件进行实验,研究选频元件谱线特性对相干合成效率的影响。实验表明:选频元件中心谱线越接近,相干合成效率越高;与此同时,选频元件的谱线宽度越宽,线形越接近重合,相干合成效率也越高,接近理想值100%。在此基础上,利用中心谱线一致的宽谱选频元件,实现两路掺Er光纤激光器的相干合成,输出功率为375 mW,相干合成效率高达99.3%。     

航空胶片的X射线标定

利用光谱扩展的荧光型软X射线单色光源产生的多条谱线,通过时间递增和光强递增的方法首次标定了国产高速航空胶片在软X射线和超软X射线波段的响应特性,给出了这种胶片的响应特性曲线即光学密度与曝光量的关系和相对光谱灵敏度曲线.     

Control and coherence of the optical transition of single nitrogen vacancy centers in diamond

We demonstrate coherent control of the optical transition of single nitrogen-vacancy defect centers in diamond. On applying short resonant laser pulses, we observe optical Rabi oscillations with a half period as short as 1 ns, an order of magnitude shorter than the spontaneous emission time. By studying the decay of Rabi oscillations, we find that the decoherence is dominated by laser-induced spectral jumps. By using a low-power probe pulse as a detuning sensor and applying postselection, we demonstrate that spectral diffusion can be overcome in this system to generate coherent photons.     

The TESIS Solar imaging spectroscopy experiment on board the CORONAS-Photon satellite

The CORONAS-Photon spacecraft was successfully launched in January 2009. Its scientific payload included the TESIS complex of telescopes and spectrometers, designed to obtain high spectral, temporal and spatial resolution solar corona images in soft X-ray to far UV spectral range.