飞秒 regime 下 CuPc 掺杂 PMMA 薄膜中的非线性吸收：实验与理论研究。（注：这里“regime”可根据具体语境灵活翻译，比如“状态”“范围”等，此处直接保留英文是因为没有更多背景信息明确其最合适的中文表述）

Nonlinear absorption in CuPc-doped PMMA thin film in the femtosecond regime: experimental and theoretical studies.

作者信息

Li Fang, Lu Peixiang, Long Hua, Yang Guang, Li Yuhua, Zheng Qiguang

机构信息

Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, PR China.

出版信息

Opt Express. 2008 Sep 15;16(19):14571-81. doi: 10.1364/oe.16.014571.

DOI:10.1364/oe.16.014571

PMID:18794992

Abstract

The nonlinear absorption (NLA) properties of copper phthalocyanine (CuPc)-doped polymethylmethacrylate (PMMA) thin film in the femtosecond regime were investigated both experimentally and theoretically. The open-aperture (OA) Z-scan measurements of the film were carried out by femtosecond laser pulse. A transition from saturable absorption (SA) to reverse saturable absorption (RSA) was observed as the excitation intensity is increased. The rate equation analysis based on an developed efficient energy level model was performed and the intensity dependence of level populations was obtained, which reveals the source of NLA. The results show that the transition from SA to RSA is ascribed to the fifth-order effect of excited-state absorption (ESA) induced by two-photon absorption (TPA) process. Furthermore, it is found that the CuPc-doped PMMA thin film possesses a large fifth-order coefficient (beta((5))) of 0.24 x 10(-21)cm(3)/W(2). It indicates that the CuPc-doped PMMA thin film could be a promising candidate for optical limiting material.

摘要

对酞菁铜（CuPc）掺杂的聚甲基丙烯酸甲酯（PMMA）薄膜在飞秒激光作用下的非线性吸收（NLA）特性进行了实验和理论研究。利用飞秒激光脉冲对该薄膜进行了开孔（OA）Z扫描测量。随着激发强度的增加，观察到了从饱和吸收（SA）到反饱和吸收（RSA）的转变。基于所建立的有效能级模型进行了速率方程分析，得到了能级粒子数的强度依赖性，揭示了非线性吸收的来源。结果表明，从SA到RSA的转变归因于双光子吸收（TPA）过程诱导的激发态吸收（ESA）的五阶效应。此外，发现酞菁铜掺杂的PMMA薄膜具有0.24×10-21cm3/W2的大五阶系数（β(5)）。这表明酞菁铜掺杂的PMMA薄膜有望成为一种光学限幅材料。