Tune调制对HIRFL-CSRm动力学孔径影响的模拟研究

 通过引进包含tune调制的传输矩阵,模拟计算了由四极铁电源纹波所引起的tune调制对HIRFL-CSRm动力学孔径的影响。模拟计算中,对HIRFL-CSRm实际(lattice)跟踪1.0×10⁶圈。从结果可以看出,动力学孔径随调制振幅的增大迅速减小,大体呈线性变化;动力学孔径随调制tune值的变化在研究范围内也有变化,变化的范围在0.049~0.089 m之间。     

Frequency Map分析在合肥光源GPLS上的应用

介绍了Frequency Map Analysis在合肥光源上的应用,通过粒子跟踪得到加入六极以及八极磁铁后合肥光源的tune漂移,根据得到的tune图分析高阶共振情况计算发现通用光源模式(GPLS)lattice处在弱共振带上.     

粒子等离子共振对有机半导体共混体系中激发复合体荧光发射的作用

研究了具有局域等离子共振特性的金纳米岛状结构阵列对高分子材料共混体系中激发复合体荧光发射特性的影响.实验结果表明,当粒子等离子共振发生在激发复合体荧光光谱区时,其荧光发射的强度得到了显著增强,且荧光寿命也得以延长.可以认为,粒子等离子共振诱发的局域场增加了激子的扩散距离,利于在相分离界面处激发复合体的形成. 关键词： 金纳米岛状结构 粒子等离子共振局域场增强效应 聚合物共混体系 激发复合体     

交变磁场下海森堡链中首尾粒子的纠缠动力学

本文研究了各向异性自旋12海森堡链中首尾粒子的纠缠动力学,其中外磁场和最近邻耦合是周期性调制的。在特定的外磁场调制频率和外磁场振幅下,将会出现纠缠共振。在某些特定频率下,最大纠缠可以在相当大的振幅范围内保持最大值。因此,可以通过外界磁场来调控纠缠。     

用逐次线性化法对储存环动力学孔径的解析研究

从逐次线性化法解粒子非线性Betatron振荡方程出发,对存在非线性六极场、八极场及六极场与八极场共存的粒子Betatron振荡方程进行研究.应用线性理论得出了粒子非线性Betatron振荡稳定性的判据,得到了动力学孔径的半解析表达式,分析了在小振幅下,导致粒子非线性不稳定性的另外一种机制———小振幅下,参量共振所引起的自激振荡.用此方法对实际lattice的动力学孔径进行了研究,所得结果与数值跟踪结果吻合得很好     

调频信号的单模激光线性模型随机共振

对单模激光增益模型的光强方程加入调频信号,用线性化近似方法计算了以δ函数形式关联的两白噪声驱动下光强的输出功率谱及信噪比. 结果表明,信噪比随抽运噪声和量子噪声强度的变化可出现典型随机共振,受调制信号振幅的影响,信噪比随载波信号频率和调制信号频率的变化出现抑制、单调上升、共振、抑制和共振等几种情况. 关键词： 抽运噪声 单模激光 随机共振 调频信号     

具有质量及频率涨落的欠阻尼线性谐振子的随机共振

以往的研究大多考虑线性谐振子模型受频率涨落噪声的影响, 而当布朗粒子处于具有吸附能力的复杂环境时, 粒子质量也存在随机涨落. 因此, 本文研究具有质量及频率涨落两项噪声的二阶欠阻尼线性谐振子模型的随机共振现象. 利用Shapiro-Loginov公式和Laplace变换, 推导了系统响应一阶稳态矩及稳态响应振幅的解析表达式. 并根据稳态响应振幅的解析表达式, 建立了稳态响应振幅关于质量涨落噪声及频率涨落噪声各自的噪声强度能够诱导随机共振现象产生的充分必要条件. 仿真实验表明, 当系统参数满足本文所给出的充分必要条件要求时, 系统稳态响应振幅关于噪声强度的变化曲线具有明显的共振峰, 即此选定参数组合能够诱导系统产生随机共振现象.     

调制振幅对粒子布居几率振荡的影响

为探讨调频场导致的量子效应的物理本质,运用密度矩阵方程和布洛赫矢量模型,对调频场作用下二能级原子系统中的粒子布居几率振荡现象进行了理论分析,讨论了光场调制振幅对振荡过程的影响。理论计算结果表明,光场调制振幅对粒子布居转移和几率振荡有较大的调制作用。当其他参量不变时,随着调制振幅的增大,粒子布居几率振荡减弱,布居转移效率增高,吸收增强。布洛赫矢量分析表明,该振荡过程是系统粒子数转移、吸收和极化三者之间的动态变化过程。     

色噪声参激和周期调制噪声外激联合驱动的分数阶线性振子的共振行为

研究了色噪声参激和周期调制噪声外激联合驱动的分数阶线性振子及其共振行为, 利用Laplace变换和Shapiro-Loginov公式, 推导出了系统响应的一阶矩及稳态响应振幅的解析表达式. 讨论了系统阶数、摩擦系数、周期驱动力频率、色噪声强度和相关率等参数对系统稳态响应的影响, 发现系统稳态响应振幅具有非单调变化的特点, 即出现了广义随机共振现象. 并且在适当参数下, 稳态响应振幅还存在具有双峰的广义随机共振现象.     

相干原子系统的失谐对脉冲调制的影响

研究了一对非共振脉冲在相干介质中的时空传播,着重考究了失谐对相干脉冲相位调制的影响。计算结果表明当脉冲在介质中稳定传播时,脉冲的最终振幅与双光子脉冲共振的情况下相同,只由介质的初始状态决定,与失谐无关。而失谐仅仅只对脉冲的相位进行调制。     

Electrically tunable magnetic configuration on vacancy-doped GaSe monolayer

Group-IIIA metal-monochalcogenides with the enticing properties have attracted tremendous attention across various scientific disciplines. With the aim to satisfy the multiple demands of device applications, here we report a design framework on GaSe monolayer in an effort to tune the electronic and magnetic properties through a dual modulation of vacancy doping and electric field. A half-metallicity with a 100% spin polarization is generated in a Ga vacancy doped GaSe monolayer due to the nonbonding 4p electronic orbital of the surrounding Se atoms. The stability of magnetic moment is found to be determined by the direction of applied electric field. A switchable magnetic configuration in Ga vacancy doped GaSe monolayer is achieved under a critical electric field of 0.6 V/Å. Electric field induces redistribution of the electronic states. Finally, charge transfers are found to be responsible for the controllable magnetic structure in this system. The magnetic modulation on GaSe monolayer in this work offers some references for the design and fabrication of tunable two-dimensional spintronic device.     

工作点反馈系统对同步辐射光源运行稳定性的提升（英文）

上海同步辐射装置(SSRF)储存环上目前已经安装了十台插入元件(IDs)。在用户时间,插入元件的间隙被反复地调整以进行科学实验。虽然使用了插入件前馈系统,但依然存在扰动束流光学的残余四极场,它会导致束流横向振荡工作点的变化,进而影响机器的性能和同步辐射光亮度的稳定。为此,我们研发了一个工作点反馈系统来解决这个问题,并且已经在上海光源储存环上投入了运行,在两周左右的运行周期内,工作点的稳定度达到了±0.001。这个反馈系统还有另一个重要功能,即可以根据监控反馈系统校正电流的变化趋势来判断二极磁铁电源和四极磁铁电源是否存在慢漂问题。为了验证这个工作点反馈的可行性,我们对使用反馈前后几周的束流参数进行了比较,包括储存环注入效率、束流寿命、水平方向束斑尺寸以及β函数的变化情况(beta-beatings)。     

工作点反馈系统对同步辐射光源运行稳定性的提升

上海同步辐射装置（SSRF）储存环上目前已经安装了十台插入元件（IDs）。在用户时间,插入元件的间隙被反复地调整以进行科学实验。虽然使用了插入件前馈系统,但依然存在扰动束流光学的残余四极场,它会导致束流横向振荡工作点的变化,进而影响机器的性能和同步辐射光亮度的稳定。为此,我们研发了一个工作点反馈系统来解决这个问题,并且已经在上海光源储存环上投入了运行,在两周左右的运行周期内,工作点的稳定度达到了±0.001。这个反馈系统还有另一个重要功能,即可以根据监控反馈系统校正电流的变化趋势来判断二极磁铁电源和四极磁铁电源是否存在慢漂问题。为了验证这个工作点反馈的可行性,我们对使用反馈前后几周的束流参数进行了比较,包括储存环注入效率、束流寿命、水平方向束斑尺寸以及β函数的变化情况（beta-beatings）。     

An IH-QCL based gas sensor for simultaneous detection of methane and acetylene

Extended wavelength tuning of an IH-QCL (integrated heater quantum cascade laser) is exploited for simultaneous detection of methane and acetylene using direct absorption spectroscopy. The integrated heater, placed within few microns of the laser active region, enables wider wavelength tuning than would be possible with a conventional DFB (distributed feedback) QCL. In this work, the laser current and heater resistor current are modulated simultaneously at 25?kHz to tune the laser over 1279.6–1280.1 cm^?1, covering absorption transitions of methane and acetylene. The laser is characterized extensively to understand the dependence of wavelength tuning on modulation frequency, modulation amplitude and phase difference between laser/heater modulation. Thereafter, the designed sensor is validated in both room-temperature static cell experiments and non-reactive high-temperature-measurements in methane-acetylene-argon gas mixtures in the shock tube. Finally, the sensor is applied for simultaneous detection of methane and acetylene during the high-temperature pyrolysis of iso-octane behind reflected shock waves.     

Classical and quantum effects in spatially modulated optical parametric oscillators

We study the effects of transverse spatial modulations in a multimode degenerate optical parametric oscillator. Intracavity photonic crystals allow us to tune the instability threshold and improve entanglement above threshold. Here we compare such results with the case in which the modulation is in the injected field profile.     

An interferometrically tuned and actively modelocked cw dye laser

An interferometer of the Michelson type is used to tune and to actively modelock an argon ion laser pumped cw dye laser. The interferometer constitutes a resonator mirror with a modulated reflecting coefficient. This modulation corresponds to a transient Fourier spectrum containing the whole emission band of the dye. In the center of this spectrum, a mode-locked train of picosecond pulses is generated. These pulses are tunable throughout the tuning range of the employed lasing medium in a simple and convenient way. Due to the inherent characteristic broad band output of the cw dye laser, the modulation envelope extends only for a fraction of the entire lasing period. Means of extending the said envelope to cover the complete laser output are discussed.     

One step synthesis of vertically aligned ZnO nanowire arrays with tunable length

Length control of ZnO nanowire arrays is a valuable concern for both fundamental research and future device application. In this article, vertically aligned ZnO nanowire arrays were synthesized by a seed layer catalyzed vapor phase transport method in a single experiment cycle. The length of these nanowire arrays exhibits a quasi-continuous evolution. It was found that the type and flow rate of carrier gas have a significant influence on the length modulation of ZnO arrays along the tube. A feasible route to tune the length of ZnO nanowire arrays from several micrometers to nearly 100 μm could be achieved by adjusting proper deposition position and carrier gas.     

High Efficient Tunable Fractal Axicon Based on LCoS

Based on the Cantor function and phase modulation, a tunable fractal axicon is formed on a liquid crystal on silicon （LCoS） with an improved generating method. It has higher focusing efficiency in higher fractal stage and approaches to 100% theoretically. The on-axis intensity keeps its fractal structure unchanged in operation of fractal stages. The tunability of the axicon is demonstrated by tune fractal stage from 1 to 3 and focal length from 0.8 m to 1 m. We also provide details of theoretical analyses and experimental results.     

利用动态微纳结构调控颜色方法的仿真研究

随着微纳米技术的进步,利用人工制备的微纳米结构实现颜色的呈现成为了可能,开辟了无油墨印刷的新思路,“结构色”的研究迅速成为该领域的焦点。提出了一种基于动态周期性微纳结构阵列的颜色调控新方法。设计在周期性微结构阵列中,填充一定厚度的功能材料薄膜,通过实时控制功能材料的外部电压,精确调控微结构上下表面的高度差,以实现在同一器件表面不同预期颜色的呈现和切换。建立了微结构的物理模型,并用时域有限差分方法(finite difference time domain,FDTD)进行了仿真研究,光源采用垂直入射的线偏振光,对微纳结构阵列上下表面高度差及结构周期进行了参数扫描,获得了系列反射光谱,并用光谱功率积分的方法计算得到了相应的颜色系列,直观地标注在CIE1931颜色空间色品图上。仿真结果表明,当微纳结构阵列周期在100~300 nm范围内时,通过调节电压改变填充的功能材料的高度,可实现全光谱范围的颜色动态调控,且反射光谱的相对峰值强度在60%左右,效率可观。该方法原理新颖,为研制动态颜色调控微器件提供了理论基础,有望在无油墨印刷、显示技术等领域获得广泛应用。