线性共轭齐聚物共轭单元依赖的光学特性

研究三种线性共轭齐聚物(F-P、F-P-F和P-F-P-F-P)的光学特性,其中吩噻嗪单元(F)和芴单元(P)交替排列. 随着共轭体系的增强,它们的吸收和发射带都逐渐红移,双光子吸收特性明显的改进. 利用连续速率分布模型分析荧光动力学的结果显示,它们的弛豫速率在逐渐增加,速率分布宽度也在变窄. 量子化学计算给出了它们的分子结构和跃迁机制,显示π共轭系统的增强促使了双光子特性的改进.     

基于电磁诱导透明的原子自旋波读出效率实验研究

光信息的存储与读出效率对量子信息领域有着重要的意义, 电磁诱导透明是最常用的方法. 本论文基于电磁诱导透明方法首次在热原子系综中实验研究了反 向和同向读取原子自旋波信息的回复效率, 并对实验结果进行了理论分析, 实验和理论的结果都表明同向和反向读出效率的高低取决于原子系综中原子自旋波的强度空间分布. 这一实验研究将会对热原子系综中的光与原子信号相互转换过程的应用有着一定的意义. 关键词： 电磁诱导透明 反向传播 原子系综     

Phase control of light amplification in steady and transient processes in an inverted-Y atomic system with spontaneously generated coherence

We investigate the effects of spontaneously generated coherence （SGC） on both the steady and transient gain properties in a four-level inverted-Y-type atomic system in the presence of a weak probe, two strong coherent fields, and an incoherent pump. For the steady process, we find that the inversionless gain mainly origins from SGC. In particular, we can modulate the inversionless gain by changing the relative phase between the two fields. Moreover, the amplitude of the gain peak can be enhanced and the additional gain peak can appear by changing the detuning of the coupling field. As for the transient process, the transient gain properties can also be dramatically affected by the SGC. Compared to the case without SGC, the transient gain can be greatly enhanced with completely eliminated transient absorption by choosing the proper relative phase between the two fields. And the inverted-Y-type system with SGC can be simulated in both atomic and semiconductor quantum well systems avoiding the conditions of SGC.