【摘要】 研究了酞菁铜薄膜的吸收光谱和飞秒三阶非线性光学极化率 χ( 3 ) .酞菁铜薄膜吸收光谱Q带的分裂是由于分子间相互作用导致酞菁的大π电子环产生畸变 ,从而使eg(LUMO)轨道的二重简并度解除 .分别采用钛宝石激光器的振荡级和放大级输出 ,用z 扫描方法测量了酞菁铜的三阶非线性光学极化率 .用激光器振荡级测量的 χ( 3 ) 值为 - 4 3× 10 -7esu ,而用激光器放大级测量的结果为 2 6 2× 10 -11esu ,前者比后者大 4个量级 .酞菁铜薄膜对激光束的吸收以及振荡级激光脉冲的高重复频率表明振荡级测量的结果主要来自热致透镜效应的贡献 ,而采用低重复频率的放大级测量得到的值才真正反映酞菁铜薄膜的本征三阶非线性光学特性更多还原

【Abstract】 The linear absorption spectrum of copper phthalocyanine (CuPc) thin film was measured, and the third order nonlinear optical susceptibility χ (3) was studied as well. The Q band splitting in the absorption spectrum of CuPc thin film is related to the distortion of phthalocyanine conjugated π electrons ring and the interaction among CuPc molecules, which leads to the split of doubly degenerated e g (LUMO) molecule orbit. Femtosecond z scan technique was used to measure the third order nonlinear optical susceptibility of CuPC thin film with the output of oscillator and amplifier stage of the Ti: sapphire laser, respectively. The χ (3) value measured with laser oscillator output was determined to be -4.3×10 -7 esu, and that with amplifier stage was 2.62×10 -11 esu; the former was four orders of magnitude larger than the latter. The discrepancy between two values was explained by the fact that with high repetition rate of the oscillator output, the absorption of laser energy by CuPc film leads to a dramatic thermal lens effect in the film, which dominates the z scan result and results in a big nonlinear parameter. While the z scan result obtained with amplifier output should really reflect the intrinsic electronic contribution to the nonlinear optical property of the CuPc film.更多还原