Development of Highly-Efficient Generation-Method for Vacuum-Ultraviolet Coherent Radiation

高效真空紫外相干辐射产生方法的开发

• 批准号: 03554008
• 负责人: HAKUTA Kohzo
• 金额: $ 5.06万
• 依托单位: University of Electro-Communications
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Developmental Scientific Research (B)
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1993
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03554008/
• 关键词: Nonlinear Optics; Inversionless Lasers; VUV-Coherent Radiation; Quantum Interferences; Atomic Hydrogen; 真空紫外; 四光波混合

The aim of this project is to develop a new type of highly-efficient generation-method for vacuum-ultraviolet coherent radiation based on nonlinear sum-frequency generation in gas-phase atoms. Gas-phase atomic hydrogen was chosen as a nonlinear medium. Coherent VUV-radiation at 122 and 103 nm (Lyman-alpha and beta radiation) was generated without suffering resonant absorption. The most important point of this method is to use an exact resonance condition for atoms for obtaining a resonantly enhanced huge nonlinearities for the medium, and simultaneously to remove resonant absorption for obtaining a transparency for the generated radiation using quantum interferences induced by strong-coupling.As a fundamental laser radiation source, a new type of single-longitudinal-mode pulsed-dye-laser was developed, which generates temporally smooth Fourier limit laser-pulse with smooth spatial profile. The smoothness both in temoral and spatial aspects is an essential issue to achieve experimental conditions for realizing the theoretical predictions. The nonlinear medium ; atomic hydrogen system, was prepared with a maximum atom-density of 5x10^<14> cm^<-3> at a temperature of 300 K through a microwave discharge for H_2 gas of 0.1 to 1 Torr.Basic physical characteristics for nonlinear optical processes using quantum interferences were investigated theoretically and experimentally. The sum-frequency generation experiments were carried out under strong-coupling condition using 40 MW/cm^2 excitation intensity with an interaction length of 5 cm. A conversion efficiency of 2x10^<-4> was achieved for 122 and 103 nm radiation. The obtained efficiency is a very high value considering the atom-density and excitation intensity. The present generation method using atmic hydrogen may offer a new possibility for various applications, such as to monitor atomic hydrogen.

该项目的目的是开发一种基于气相原子非线性和频产生的新型真空紫外相干辐射高效产生方法。选择气相原子氢作为非线性介质。产生 122 和 103 nm 的相干 VUV 辐射（莱曼 α 和 β 辐射），而不会遭受共振吸收。该方法最重要的一点是利用原子的精确共振条件来获得介质的共振增强的巨大非线性，同时消除共振吸收，利用强耦合引起的量子干涉获得所产生的辐射的透明度。作为一种基本的激光辐射源，开发了一种新型单纵模脉冲染料激光器，它产生 具有平滑空间轮廓的时间平滑傅立叶极限激光脉冲。时间和空间方面的平滑性是实现理论预测的实验条件的重要问题。非线性介质；通过0.1～1 Torr H_2气体微波放电，在300 K温度下制备了最大原子密度为5x10^<14> cm^-3>的原子氢体系。从理论上和实验上研究了利用量子干涉的非线性光学过程的基本物理特性。和频发生实验在强耦合条件下进行，激发强度为40 MW/cm^2，相互作用长度为5 cm。对于122和103nm辐射实现了2×10 ^ -4 的转换效率。考虑到原子密度和激发强度，所获得的效率是一个非常高的值。目前使用原子氢的生成方法可能为各种应用提供新的可能性，例如监测原子氢。

项目成果

G.Z.Zhang: "Scanning geometry for broadly tunable single-mode pulsed dye lasers" Optics Letters. 17. 997-999 (1992)

G.Z.Zhang：“广泛可调单模脉冲染料激光器的扫描几何结构”光学快报。

K.Hakuta: "Second Harmonic Generation with Reduced Absorption in Atomic Hydrogen" Laser Spectroscopy X:Proceedings of Tenth International Conference on Laser Spectroscopy. 10. 301-306 (1992)

K.Hakuta：“原子氢吸收减少的二次谐波”激光光谱学 X：第十届国际激光光谱学会议论文集。

白田耕蔵: "無反転分布レーザー" 学会出版センター. (出版予定).

白田幸三：《非人口反转激光》学会出版中心（待出版）。

K.Hakuta, G.Z.Zhang, R.I.Thompson, and B.P.Stoicheff: ""Nonlinear Optical Generation with Electromagnetically Induced Transparency in Atomic Hydrogen" AIP Conference Proceedings : Laser Spectroscopy. 290. 279 (1994)

K.Hakuta、G.Z.Zhang、R.I.Thompson 和 B.P.Stoicheff：“原子氢中具有电磁感应透明度的非线性光学生成”AIP 会议记录：激光光谱学。290. 279 (1994)

K. Hakuta, L. Marmet, and B. P. Stoicheff: "Electric-Field-Induced Second-Harmonic Generation with Reduced Absorption in Atomic Hydrogen" Physical Review Letters. 66. 596 (1991)

K. Hakuta、L. Marmet 和 B. P. Stoicheff：“电场诱导的二次谐波产生，原子氢吸收减少”物理评论快报。