Two-Photon Fluorescence Property and Ultrafast Dynamics of Two Dipolar Compounds with Dipicolinate as Electron Acceptor

Linear and nonlinear photophysical properties of two novel dipolar compounds named as trans- dimethyl-4-[4＇-（N,N-dimethylamino）-styry1]-pyridin-2,6-dicarboxylate （Xiao-1） and trans-dimethyl-4-[4＇-（N,N-diphenylamino）-styry1]-pyridin-2,6-dicarboxylate （Xiao-2） are investigated by steady-state absorption and fluorescence spectroscopy, Z-scan and two-photon excited fluorescence measurements. Strong two-photon fluorescence emission and the pronounced positive solvatochromism are observed from two compounds. The two-photon absorption cross section of Xiao-2 is about 1.5 times larger than that of Xiao-1. One-color and two-color femtosecond pump-probe experiments are employed to investigate the excited state dynamics of two compounds. The relaxation lifetime of the intra-molecular charge transfer state is determined to be in the hundreds of picosecond domain for both the compounds in THF, and several tens of picosecond in DMSO solutions.     

Nonlinear Optical Properties and Ultrafast Dynamics of Undoped and Doped Bulk SiC

Ultrafast third-order nonlinear optical response of bulk 6H-SiC undoped and doped with different nitrogen concentrations are investigated utilizing femtosecond Z-scan and optical Kerr effect （OKE） techniques at the wavelength of 800hm. The Z-scan measurement shows that the third-order nonlinear optical susceptibilities of the doped samples are improved in comparison to the intrinsic sample. The OKE results additionally reveal that the instantaneous nonlinear optical response of the samples can be ascribed to the distortion of the electron cloud. The ultrafast transient spectroscopic measurements with the one-color and two-color pump-probe techniques demonstrate that the ultrafast recovery process in subpicosecond domain is induced by two-photon absorption process, while the slow relaxation component reflects the carrier dynamics of the excited electrons.     

有机双光子吸收材料的研究进展

本文综述了具有优异双光子吸收/双光子荧光性质的有机功能材料的研究工作和成果。近年来,有机材料凭借其出众的性质、丰富的种类、多重功能性以及快速的非线性光学响应引起国际科学和技术界的极大兴趣。文章介绍了测量材料的非线性光学性质和超快响应的实验方法,它们已被广泛应用于有机材料的研究工作,并且取得了重大的进展。本文描述了对偶极、四极、多枝结构、大环结构以及聚合物等有机材料的非线性光学性质和超快光学响应的研究结果。基于有机材料的迷人性质,具有优异非线性光学性质和超快响应的有机材料将会在很多领域显示出巨大的应用潜力。     

一种新型蓝光发射聚合物的非线性光学性质和超快动力学

以一种新型蓝光发射聚合物多聚(5-二苯胺基)-1,3-苯乙烯(Yu1)及其单体材料5-二苯胺基苯基-1,3-二甲醛(Yu0)为研究对象, 利用飞秒Z扫描技术和泵浦-探测技术研究了这两种材料的非线性光学性质以及超快动力学. 结果表明, 聚合后, 聚合物Yu1的双光子吸收性质得到显著增强, 每重复单元的双光子吸收截面达到单体Yu0的10倍. 超快动力学研究结果揭示了Yu0和Yu1的不同弛豫过程. 聚合物Yu1的400 nm单色泵浦-探测实验结果表现出明显的各向异性: 由于激子迁移的高度方向性, 泵浦光与探测光偏振方向平行配置时观察到的快过程在偏振方向垂直配置时消失. 非线性光学性质以及超快动力学研究结果表明聚合单体对非线性性质的增强效应.