Novel two-photon reasonant nonlinear-optical phenomena and their application for exploring electronic structures in solids

新型双光子推理非线性光学现象及其在探索固体电子结构中的应用

基本信息

批准号：
05452035
负责人：
INOUE Kuon
金额：
$ 4.74万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

A few novel nonlinear-optical phenomena due to two-photon resonance with excited state in condensed matters are found. Those phenomena are 1) resonant second-harmonic generation in the fogeometry forbidden in the usual dipole approximation, 2) resonant hyper-Raman scattering by LO phonon, and 3) four-wave mixing phenomenon in the Brewster-angle configuration. Their profiles were experimentally studied in detail, and thereby the mechanisms have been clarified. By using these phenomena as novel spectroscopic tools, the electronic structures including biexciton in several quantum-confined semiconductors such as II-VI compound quantum wells (QWs) and quantum dots (QDs) are clarified. In particular, the band-offsets and the excitonic binding energy EX in an ultra-thin ZnSe/ZnS QW have been for the first time determined ; a prominent enhancement of Ex due to confinement is found. The existence of a biexciton is evidenced for the first time in both ZnSe/ZnS and ZnS/ZnSSe QWs. As a result, striking enhancement of the biexciton binding energies are also observed. For these purposes, new-types of spectroscopic techniques, i.e., two-photon absorption, cw Brewster-angle reflection, and transient (time-resolved) reflection of a femtosecond pulse in the Brewster-angle geometry, which dominantly reflects free-induction decay of coherent excitation, have also been developed.Thus, all those phenomena newly developed have been demonstrated to provide useful tools for exploring electronic structures, particularly in quantum-confined systems. The present outcomes have been or will be published in 8 to 10 papers.

发现了由于凝聚态物质中激发态的双光子共振而产生的一些新颖的非线性光学现象。这些现象是 1) 在通常的偶极近似中禁止的雾几何中的共振二次谐波产生，2) LO 声子的共振超拉曼散射，以及 3) 布鲁斯特角配置中的四波混合现象。对它们的概况进行了详细的实验研究，从而阐明了其机制。通过使用这些现象作为新颖的光谱工具，阐明了几种量子限制半导体（例如 II-VI 化合物量子阱（QW）和量子点（QD）中的双激子）的电子结构。特别是，首次确定了超薄 ZnSe/ZnS QW 中的能带偏移和激子结合能 EX；发现由于限制而导致 Ex 显着增强。首次在 ZnSe/ZnS 和 ZnS/ZnSSe 量子阱中证明了双激子的存在。结果，还观察到双激子结合能的显着增强。为了这些目的，新型光谱技术，即双光子吸收、连续布儒斯特角反射和布儒斯特角几何中飞秒脉冲的瞬态（时间分辨）反射，主要反映自由感应衰变因此，所有这些新开发的现象都被证明可以为探索电子结构，特别是在量子限制系统中提供有用的工具。目前成果已经或即将发表8至10篇论文。