Nonlinear optrical properties of the natural quantum-well materials

研究了天然量子阱材料中激子的线性和非线性光学性质，得到了以下结果：磁光研究（C_6H_<13>NH_3）_2PbI_4及其相关化合物中的激子为强局域化的Frenkel型激子，主要由Pb^<2+> 6s 6p轨道组成。用ns脉冲激光对（C_6H_<13 bbb_nh_3）_2PbI_4进行了非线性光谱泵浦验证实验，获得了高达50%的强吸收饱和度。这对应于chi^<(3)> - 10^<-4 >esu。在光致发光测量中，观察到强烈的“非线性”发光峰。不幸的是，它的起源还不清楚。用ns脉冲激光在（C_6H_<13>NH_3）_2PbI_4上进行了简并四波混频实验，测量了简并四波混频chi^<(3)>光谱。得到的chi^<(3)>在室温下达到6 X 10^<-4> esu，在77 K时达到2.4 X 10^<-3> esu，与吸收峰有很强的单光子共振。这些chi^<(3)>值比THG测量的10^<-9 >esu大得多。为了研究chi^<(3)>的起源，时间分辨泵浦探针实验正在进行中。

Linear and nonlinear optical properties of excitons in the natural quantum-well materials have been investigated and the following results have been obtained.1. Magnetooptical studyExcitons in (C_6H_<13>NH_3)_2PbI_4 and other related compounds are strongly localized Frenkel type excitons mainly composed of Pb^<2+> 6s 6p orbitals.2. Nonlinear spectroscopyA pump-prove experiment was paeformed on ((C_6H_<13>NH_3)_2PbI_4 using a ns pulse laser, and a strong absorption saturation up to 50 % was observed. This corresponds to chi^<(3)> - 10^<-4> esu. In a photoluminescence measurement, a strong "nonlinear" luminescence peak was observed. Unfortunately, its origin has not been understood.3. Degenerate four wave mixingchi^<(3)> spectra were measured by degenerate four wave mixing experiments on (C_6H_<13>NH_3)_2PbI_4 using a ns pulse laser. The obtained chi^<(3)> reaches 6 X 10^<-4> esu at room temperature and 2.4 X 10^<-3> esu at 77 K showing strong one-photon resonances to the absorption peaks. These chi^<(3)> values are much larger than that measured by THG, 10^<-9> esu.In order to investigate the origin of the lager chi^<(3)>, time-resolved pump-probe experiments are now underway.