Optimization of High-Order Harmonic by Genetic Algorithm for the Chirp and Phase of Few-Cycle Pulses

The brightness of a particular harmonic order is optimized for the chirp and initial phase of the laser pulse by genetic algorithm. The influences of the chirp and initial phase of the excitation pulse on the harmonic spectra are discussed in terms of the semi-classical model including the propagation effects. The results indicate that the harmonic intensity and cutoff have strong dependence on the chirp of the laser pulse, but slightly on its initial phase. The high-order harmonics can be enhanced by the optimal laser pulse and its cutoff can be tuned by optimization of the chirp and initial phase of the laser pulse.     

Carrier－Envelop Phase－Dependent Effect on Photoelectron Angular Distribution in Single－Cycle Laser Pulses ＊

Using a nonperturbative scattering theory, We study the photoelectron angular distributions (PADs) of Kr atoms irradiated by an infinite sequence of intense single-cycle pulses of circular polarization. We demonstrate the inversion asymmetry of PADs and the dependence of PADs on the carrier-envelop phase of the single-cycle pulses. The inversion asymmetry is caused by the interference between transition channels where the different channels are characterized by different combinations of absorbed-photon numbers in the ionization process. Our results provide a possible method to determine the value of carrier-envelop phase by the detected PADs.     

采用圆偏振啁啾飞秒激光脉冲操控CS2分子的相干拉曼散射过程

采用两束圆偏振啁啾飞秒激光脉冲,非共线相干激发三原子分子CS₂液体. 在相位匹配的方向上,探测到由CS₂频率为397 cm^-1的振动模式产生的强度对称分布的相干反斯托克斯拉曼散射(CARS)信号和相干斯托克斯拉曼散射(CSRS)信号. 当调整两束激发光的圆偏振状态时,CARS,CSRS信号的强度、偏振、波长均发生规律性的改变:CARS,CSRS信号的强度分布反映了CS₂ 在不同极化状态下的受激拉曼散射截面大小;信号光的 关键词： 啁啾脉冲 相干反斯托克斯拉曼散射(CARS) 相干斯托克斯拉曼散射(CSRS) 2')" href="#">CS₂     

黑卵蜂寄主识别利它素的性质研究

通过盐析、柱层析和分子筛层析，从松毛虫雌蛾附腺中分离到一种ＳＰ－Ｉ组份，经生化方法检测鉴定，此组份是一种糖蛋白，分子量为１．３５×１０５，等电点为４．２，蛋白质含量９２％，糖含量８％．它能引诱松毛虫黑卵蜂和松茸毒蛾黑卵蜂在非天然寄主上的产卵检查、刺探行为，是一种黑卵蜂寄主识别利它素．     

Plasma-induced spatiotemporal modulation of propagating femtosecond pulses

The dynamics of the femtosecond pulse propagation in a plasma channel is investigated by the pump-probe longitudinal diffractometry and second harmonic generation frequency-resolved optical gating (SHG-FROG) technique. The spatial characteristics, corresponding to the electronic density and the size of the channel, can be observed by the recorded ring pattern, and the spectral and temporal characteristics are recorded by the SHG-FROG traces. The spatiotemporal characteristics will help us to better understand the dynamics of the plasma induced by the femtosecond pulse and the femtosecond pulse propagating in the plasma channel.     

Achievement of Narrow-Band CARS Signal by Manipulating Broad-band Laser Spectrum

We theoretically demonstrate the achievement of narrow-band coherent anti-Stokes Raman scattering （CARS） signal by manipulating broad-band probe spectrum. The narrowing of the CARS signal depends on the spectrum bandwidth of the probe beam, and thus high-resolution CARS signal for a complicated quantum system can be obtained by the simple spectrum manipulation. Furthermore, the energy-level diagram for the complicated quantum system can also be labelled by measuring the CARS signal at a given frequency.     

碰撞对钠分子菱形能级系统中高位能能布居的影响

在实验室上研究了碰撞过程对钠分子菱形能级系统高位能级布居的影响.无多普勒加宽的洛仑兹尖峰随缓冲气体压力的增大很快消失;加入少量缓冲气体,碰撞激发过程对以多普勒宽度为特征的信号有一定的增强作用,但加入过量缓冲气体会由于消布居作用使信号减弱.上述结果在速率方程近似下加以解释.     

1-(2-吡啶偶氮)-2-萘酚薄膜的非线性光学特性研究

运用Ｚ扫描方法研究了１－（２－吡啶偶氮）－２－萘酚薄膜的非线性光学特性。用皮秒脉冲激光测得在５３２ ｎｍ 处、光强较低时χ（３）Ｒ ＝ １．２９×１０－ ９ ｅｓｕ, β＝ ４２ ｃｍ ／ＧＷ; 同时研究了不同光脉冲能量时的非线性吸收特性, 发现其非线性吸收随着光强的增大由反饱和吸收转为饱和吸收     

稀土镧离子对1,10-二氮杂菲紫外荧光的增强效应

测量了１,１０－二氮杂菲和硝酸［二－（１,１０－二氮杂菲）合镧］甲醇溶液的单光子和双光子激发紫外荧光谱。研究表明：镧离子的配位对１,１０－二氮杂菲的紫外荧光效率具有显著的增强作用,镧离子的桥梁作用增强了１,１０－二氮杂菲之间的耦合,并引起１,１０－二氮杂菲紫外荧光谱的红移。     

温梯法生长的Ti:Al2O3晶体的光谱分析

本文研究了不同掺Ti^3＋浓度对温梯法生长的Ti：Al2O3晶体吸收光谱、荧光光谱和X射线衍射光谱的影响。根据吸收光谱提出了一个色心模型。对比了样品各处420nm荧光谱，发现掺Ti^3＋浓度越大，该处荧光强度越弱，同时解释了420肿处荧光峰的起源。对比了样品各处720nm处的荧光谱，发现掺Ti^3＋浓度越大，该处荧光强度越强。X射线衍射谱（XRD）表明，衍射峰强度随掺Ti^3＋浓度的增大而逐渐增强。