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Characterization of a high harmonics beam line for the application of time-resolved spectroscopy

用于时间分辨光谱应用的高次谐波光束线表征

基本信息

批准号：
17204033
负责人：
SEKIKAWA Taro
金额：
$ 29.95万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

The mission of this project is to characterize high harmonic pulses to apply to time-resolved photoelectron spectroscopy. The research issues we have accomplished are 1) the efficient pulse compression to 5 fs using metal-coated hollow fiber and 2) the development of a new characterization technique of high harmonic pulses. These issues were raised 1) to generate high harmonic pulses efficiently from 5-fs laser pulses and 2) to apply high harmonic pulses to time-resolved spectroscopy more conveniently.Few-cycle laser pulses are used to generate attosecond high harmonic pulses. To generate intense attosecond pulses, the pulse energy of few-cycle laser pulses should be boosted. Therefore, we used an aluminum coated hollow fiber in the fiber compression to improve the transmittance efficiency, improved from 40% to 70% under the same experimental condition. Finally, we could obtain the 5-fs, 660-μJ pulses after compressed by chirped mirrors. These will be very useful to generate attosecond pulses.We propose a new characterization technique of high harmonic pulses based on the spectral shearing interferometry. In this method, optical pulses are copied on the photoelectron wave packet by the photoelectric effect. Using neon or argon atoms as a target, a pair of spectral sheared photoelectron wave packets is generated because neon and argon have two ionization energies. From the spectral sheared photoelectron wave packets, the spectral dispersion can be extracted. This method is quite simple and has high sensitivity. We applied this method to the 19th harmonic of Ti:sapphire laser and could generate 3.7-fs pulses, although the pulse duration of the laser pulse was 36 fs. The nonadiabatic rising of the laser electric field can explain the relatively short pulse duration.

本计画的使命是研究高次谐波脉冲的特性，以应用于时间分辨光电子能谱。我们已经完成的研究问题是：1）使用金属涂层中空光纤有效地将脉冲压缩到5 fs; 2）发展了一种新的高次谐波脉冲表征技术。本文提出了两个问题：1）如何有效地从5 fs激光脉冲中产生高次谐波脉冲; 2）如何更方便地将高次谐波脉冲应用于时间分辨光谱学。为了产生高强度的阿秒脉冲，需要对几个周期的激光脉冲进行能量提升。因此，我们在光纤压缩中使用了铝涂层的中空光纤来提高透过率，在相同的实验条件下，透过率从40%提高到70%。最后通过啁啾镜压缩，获得了5 fs、660 μJ的脉冲。提出了一种基于光谱剪切干涉的高次谐波脉冲的表征技术。该方法利用光电效应将光脉冲复制到光电子波包上。由于氖和氩原子具有两个电离能，用氖或氩原子作靶，产生了一对光谱剪切光电子波包。从光谱剪切光电子波包中，可以提取光谱色散。该方法简单、灵敏度高。我们将这种方法应用于钛宝石激光器的19次谐波，可以产生3.7-fs的脉冲，虽然激光脉冲的脉冲宽度为36 fs。激光电场的非绝热上升可以解释相对较短的脉冲宽度。