聚合物非醚PPQ三阶非线性光学系数的激发态增强

Excited-State Enhancement of the Third-Order Nonlinear Optical Susceptibility of Non-Ether PPQ

用皮秒时间分辨的双波耦合方法研究了有机高聚物非醚ＰＰＱ（ｐｏｌｙｐｈｅｎｙｌｑｕｉｎｏｘａｌｉｎｅｓ）的三阶非线性光学增强。在激发效率未饱和的情况下观察到材料的有效三阶超极化率γ增强两倍。与激发荧光实验相结合，验证了γ的激发增强与激发态粒子布居数成线性关系；并用三能级模型解释了实验观测到的激发态增强的时间过程。

Picosecond time-resolved two-wave coupling method is used to investigate the excited-state enhancement of the third-order nonlinear optical process of a organic polymer──non-ether PPQ (polyphenylquinoxalines). The enhancement factor of the material's effective third-order hyperpolarizability γ is observed to be 2 under the nonsaturable exciting condition, and excited fluorescence of non-ether PPQ was also examined. We verified that the excited-state enhancement of γ is proportional to the population of the excited state, and explained the time process of the enhancement using three-level model.