Nonlinear optrical properties of the natural quantum-well materials

研究了自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_NH_3<13>）_2PbI_4及其它相关化合物中的激子是强定域的Frenkel型激子，主要由Pb^&lt;2+&gt; 6s 6p轨道组成.用纳秒脉冲激光对（（C_6H_NH_3）_2PbI_4）进行了泵浦验证实验<13>，观察到了50%的强吸收饱和。这对应于chi^&lt;（3）&gt; - 10^<-4>esu。在光致发光测量中，观察到强的“非线性”发光峰。不幸的是，它的起源一直没有被理解。用纳秒脉冲激光对（C_6H_NH_3）_2PbI_4进行了简并四波混频实验，测量了简并四波混频χ ^&lt;3&gt;谱<13>。在室温和77 K下，x ^&lt;3&gt;分别达到6 × 10 ~（10）<-4>esu和2.4 × 10 ~（10）<-3>esu，表现出较强的单光子共振。这些chi^&lt;3&gt;值比THG测量的值大得多<-9>，为研究大chi^&lt;3&gt;的起源，时间分辨泵浦探测实验正在进行中。

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.