Molecular assemblies for ultrafast nanophotonics

本项目主要涉及几种有机分子组件的超快光响应的构建和检测，包括尺寸量子化的硫化镉纳米粒子和离子对电荷转移络合物，有机分子激发态的非线性光学性质的评估，以及这种光响应材料在全光数据处理中的应用。来自澳大利亚、德国和日本的科学家合作进行了这项研究，主要目标是：1)在阴离子聚合物薄膜和水溶液中形成尺寸量化的高发光纳米硫化镉；2)控制硫化镉纳米颗粒的尺寸和表面处理，以显著减少缺陷或陷阱；3)测量飞秒激光闪光光解的超快光响应，并检查尺寸和表面处理对光响应动力学的影响；4)构建包含这些…的新型导波模式几何结构本文的主要研究成果如下：1)制备了直径为3·7~5·4 nm的直径为3·7~5·4 nm的具有很强激子发光的纳米硫化镉颗粒，如果有缺陷发光的话，在水溶液中没有或有很弱的缺陷发光；(2)观察到了一个极快的(τ&lt；0.7ps)激子漂白后对发光激活的硫化镉纳米粒子进行激光激发后的恢复分量。3)计算激发态下的二阶非线性光学常数超极化率。4)证明了有机染料导模几何结构对ns-fs激光激发的反射光的超快平行光调制。较少

This project dealt primarily with the construction and examination of ultrafast photoresponses of several organized molecular assemblies, including size-quantized CdS nano-particles and ion-pair charge-trans- fer complexes, evaluation of nonlinear optical properties of organic molecules at the excited state and also with application of such photoresponses materials in all-optical data processing. Scientists from Australia, Germany and Japan collaborated in this study, with the main objectives being,1) Formation of size-quantized and highly luminescent CdS nano-particles in anionic polymer films, and in aqueous solutions ; 2) Control of CdS nano-particle sizes and their surface treatments to considerably decrease defects or traps ; 3) Measurement of ultrafast photoresponses by femtosecond (fs) laser flash photolysis, and an examination of the effect of size and surface conditioning on the dynamics of the photoresponse ; 4) Construction of novel guided wave mode geometry containing these … More photoresponsive materials in order to apply them in parallel optical data processing based on photoinduced ultrafast changes of absorption, refractive index or luminescence.Followings are some of main results obtained from the present study, which will contribute a great deal to construct all-optical data processing in the near future based on ultrafast photoresponses of organic molecules and inorganic nano-particles.1) Preparation of CdS nano-particles with a diameter of 3.7-5.4 nm showing very strong exciton lumines- cence and none or very weak, if any, defect luminescence in aqueous solutions.2) Observation of an extremely fast (τ<0.7 ps) recovery component after exciton bleaching upon fs laser excitation of luminescence activated CdS nano-particles.3) Evaluation of the second order nonlinear optical constant, hyperpolarizability, at the excited state.4) Demonstration of ultrafast parallel optical modulation of reflected light by guided mode geometry containing organic dyes upon ns-fs laser excitation. Less