Molecular assemblies for ultrafast nanophotonics

本项目主要研究了几种有组织分子组合的超快光响应的构建和检测，包括尺寸量子化CdS纳米粒子和离子对电荷转移配合物，有机分子在激发态下的非线性光学性质的评估以及这些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子化和高度发光的CdS纳米颗粒；2)控制CdS纳米颗粒尺寸及其表面处理，以显著减少缺陷或陷阱；3)利用飞秒（fs）激光闪光光解技术测量超快光响应，并研究了尺寸和表面条件对光响应动力学的影响；4)基于光致吸收、折射率或发光的超快变化，构建包含这些光响应材料的新型导波模几何结构，以便将其应用于光致吸收、折射率或发光的超快变化并行光学数据处理。以下是本研究获得的一些主要结果，这些结果将有助于在不久的将来建立基于有机分子和无机纳米粒子的超快光响应的全光数据处理。1)制备了直径为3.7 ~ 5.4 nm的CdS纳米粒子，具有很强的激子发光，在水溶液中无缺陷发光或缺陷发光很弱。2)观察到激光激发发光活化CdS纳米粒子激子漂白后极快（τ<0.7 ps）的恢复成分。3)激发态下二阶非线性光学常数超极化率的计算。4)利用含有机染料的导模几何结构在ns-fs激光激发下实现反射光的超快平行光调制。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