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FEMTOSECOND PULSE COMPRESSION WITH NONLINEAR CASCADING PHASE-SHIFT EFFECTS

具有非线性级联相移效应的飞秒脉冲压缩

基本信息

批准号：
13650041
负责人：
HARIMOTO Tetsuo
金额：
$ 1.34万
依托单位：
UNIVERSITY OF YAMANASHI
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650041/
关键词：
cascading effects ultra-short pulses nonlinear optics

项目摘要

We demonstrated that an initial phase mismatch in type I second-harmonic generation processes with ultrahigh intensity laser pulses can be used to compensate for third-order nonlinearity not only in temporal profiles but also in spatial distributions of fundamental and second-harmonic pulses. The spatial profile of the second-harmonic pulse shows a good reappearance of the input fundamental pulse throughout the compensation for the third-order nonlinearity.We demonstrated that a frequency chirp initially introduced to fundamental pulse can be used to effectively suppress cubic nonlinear effect in a type I second-harmonic generation with ultra-high intensity laser pulses. The energy conversion efficiency can be increased by a factor of 1.23 with good temporal and spatial profiles of second-harmonic pulse in comparison with conventional schemes of second-harmonic generation.Theoretical analysis and numerical calculation for cascading effects in type I second-harmonic generation are described for two cases as the following: (1) a type I second-harmonic generation provided that group-velocity mismatch, group-velocity dispersion, diffraction, walk-off and absorption can be neglected; (2) a type I second-harmonic generation with picosecond laser pulses involved the group-velocity mismatch, group-velocity dispersion and walk-off. In addition, numerical results for a type I second-harmonic generation with a KDP crystal are also given.We propose a simple OPCPA scheme to increase the energy conversion efficiency from the pump to seed by introducing a time delay between the long pump and short seed pulses so that the seed pulse interacts with all portions of the pump pulse, and the gain is guaranteed simultaneously. We will present numerical results for the proposed OPCPA scheme and demonstrate that the pump energy can be efficiently transferred into the seed and idler pulses.

我们证明了，在I型二次谐波产生过程中的初始相位失配与高强度的激光脉冲，可以用来补偿三阶非线性不仅在时间上的轮廓，而且在空间分布的基本和二次谐波脉冲。在对三阶非线性进行补偿的过程中，二次谐波脉冲的空间分布很好地再现了输入基波脉冲，证明了在超高强度激光脉冲产生I类二次谐波时，在基波脉冲中引入频率啁啾可以有效地抑制三阶非线性效应。与传统的二次谐波产生方案相比，该方案的能量转换效率可提高1.23倍，并具有良好的二次谐波脉冲的时间和空间分布。（1）在群速度失配、群速度色散、衍射、走离和吸收可以忽略不计的情况下，I型二次谐波产生;（2）皮秒激光脉冲的I类二次谐波产生涉及到群速度失配、群速度色散和走离。此外，还对KDP晶体I类二次谐波产生进行了数值模拟，提出了一种简单的OPCPA方案，通过在长抽运脉冲和短种子脉冲之间引入时间延迟，使种子脉冲与抽运脉冲的所有部分相互作用，同时保证增益，从而提高了从抽运脉冲到种子脉冲的能量转换效率。我们将提出建议的OPCPA计划的数值结果，并证明泵浦能量可以有效地转移到种子和空闲脉冲。