掺Er3+玻璃上转换荧光的时间相干控制

在无序固体掺Er3 玻璃中实施了时间相干控制,对波长为670 nm的上转换荧光进行了调制,荧光强度随着延迟时间的变化而振荡变化,通过拟合得到波包的退相特征时间为300 fs;同时由光子回波信号测得由声子作用引起的波包退相特征时间.上述两个数据的一致性表明波包的快速退相是玻璃基底的声子作用引起的,从而为探索在无序固体中的相干时间控制提供了线索.     

Y型四能级中的双电磁感应透明和超窄吸收

采用密度矩阵方程．对双光场耦合的分子Y型四能级系统的粒子数分布和吸收特性进行了计算和分析,在此能级系统中得到了双暗态共振和双电磁感应透明．并讨论了相应的物理机制。同时,我们讨论了Y型四能级两个上能级的自发辐射产生的量子干涉效应对电磁感应透明的影响,发现自发辐射干涉相消可以产生超窄线宽和导致探测光的吸收增强,自发辐射干涉相长可以展宽谱线和减弱探测光的吸收,并运用缀饰态理论对以上计算结果进行分析,与采用密度矩阵方程的计算结果一致。     

Coherent Phase Control of Multiphoton Ionization in Three-Level Ladder-Type System

We present the theoretical investigation of photoelectron spectroscopy resulting from the strong field induced multiphoton ionization in a typical three-level ladder-style system. Our theoretical results show that the photo-electron spectral structure can be alternatively steered by spectral phase modulation. This physical mechanism for strong field quantum control is explicitly exploited by the time-dependent dressed state population. It is concluded that the phase-shaped laser pulses can be used to selectively manipulate the multiphoton ionization process in complicated quantum systems.     

High Resolution Mode-Selective Excitation by Adaptive Femtosecond Pulse Shaping

High resolution mode-selective excitation in the mixture of C6H6 （992 cm^-1） and C6D6 （945 cm^-1） is experimentally achieved by adaptive femtosecond pulse shaping based on the genetic algorithm （GA）, and second harmonic generation frequency-resolved optical gating （SHG-FROG） is adopted to characterize the original and optimal laser pulses, and its mechanism is experimentally validated by tailoring the frequency components of the pump pulses at the Fourier plane. It is indicated that two-pulse coherent mode-selective excitation of the Raman scattering mainly depends on the effective frequency components of the pump pulse related to specific molecular vibrational mode. The experimental results have attractive potential applications in the complicated molecular system.     

Theoretical Investigation of Coherent Enhancement for Resonant Two-Photon Transitions

We theoretically investigate the coherent enhancement of resonant two-photon transitions （TPT） in a three-level atomic system. The TPT can be coherently enhanced by modulating spectral amplitude due to eliminating the destructive interference, though partial laser energy losses. Maximal enhancement of TPT can be achieved by modulating spectral phase due to establishing completely constructive interference. Our research provides a theoretical basis for experimental investigation and appears to have potential application on coherent control in the complicated quantum system.     

利用干涉探测技术对相干声子的研究

利用带有环形回路的干涉探测装置,研究了光程差精确为零时参考光和探测光的相干振荡信号,对数据的拟合给出了相干声子诱导的折射率相关变化.由信噪比较高的反射率相位变化信号,不仅清楚地辨别出铝膜中的四种相干声子模式,还分辨出声子回波信号.     

由宽波段双光子泵浦的铷光解离受激发射光谱

本文报导了由宽波段双光子泵浦铷分子,使之光解离而产生位于2.25、2.29和2.73μm的受激辐射的实验结果。当氮分子泵浦的染料激光输出从6500A扫描到7050A时,始终可探测到分别对应于6P_(3/2)—4D_(5/2)、6P_(1/2)—4D_(3/2)和6P_(3/2)—6S跃迁的三条受激发射线。文中对上述结果和机理进行了讨论。     

多普勒加宽非匹配Λ型能级系统的无反转增益效应

对Λ型能级系统连续波无反转增益效应的研究表明,在耦合光的拉比频率小于多普勒宽度的情况下,多普勒加宽的非匹配能级系统(耦合光波长λc小于探测光波长λp)的无反转增益不仅存在,而且还强于匹配系统(λc=λp)的无反转增益,文中从与无反转增益紧密联系的电磁感应透明(EIT)的角度对这一现象作了解释.     

高激发态钠原子与分子碰撞能量转移及分子扩散带辐射的增强效应研究

在钠原子分子混合体系中 ,实验研究了加入缓冲气体对高位态原子分子碰撞能量转移和分子扩散带辐射的增强效应 ;运用瞬态碰撞模型作了理论计算 ,理论结果与实验结果相符合     

Optimal Control of Population Transfer in Three-Level A System with Genetic Algorithms

Population transfer in a three-level A system is simulated numerically and optimized. Almost complete population transfer from |1) to |3) is achieved by a genetic algorithm while the population in state |2) reached minimum over the entire evolution at the same time. The result shows that the optimal pulse sequence is the well-known stimulated Raman adiabatic passage (STIRAP) scheme. The detuning of pump pulse and Stokes pulse Δp and Δs with the opposite sign and the chirps χp and χs with the same sign are in favour of the complete and robust population transfer for few-cycle laser pulse. Rabi frequencies Ωp and Ωs have insensitive effects on the complete population transfer during a large scope of their ratio when they are large enough.