Generation of an isolated sub-100 attosecond pulse in the water-window spectral region

• Published in: Chinese physics B Vol. 19; no. 1; pp. 589 - 594
• Main Author: 邹璞 李儒新 曾志男 熊辉 刘鹏 冷雨欣 范品忠 徐至展
• Format: Journal Article
• Language: English
• Published: IOP Publishing 2010
• Subjects: 光谱宽度; 孤立子; 电子动力学; 脉冲产生; 脉冲持续时间; 阿秒脉冲
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/19/1/019501

We propose a scheme to generate isolated attosecond pulses in the water-window spectral region. Based on the numerical solutions of the single active electron model, we investigate high-order harmonic generation in helium atoms driven by a multi-cycle two-colour optical field synthesized by an intense 2000 nm, 20 fs pulse and its frequency-doubled pulse. When the latter is slightly detuned and properly phase shifted with respect to the fundamental laser pulse, an ultra-broad extreme ultraviolet supercontinuum with a spectral width of 130 eV can be generated in the 270 400 eV spectral regions. A supercontinuum from 280-340 eV in the water window can be selected to yield an isolated 67 attosecond pulse without employing any phase compensation. This water window coherent x-ray pulse with less than 100 attosecond duration is a potential tool for studying the ultrafast electronic dynamics of biological samples in water.