Tsarev M V, Bakunov M I
Opt Express. 2019 Feb 18;27(4):5154-5164. doi: 10.1364/OE.27.005154.
It was recently predicted [M. I. Bakunov, A. V. Maslov, and M. V. Tsarev, Phys. Rev. A95, 063817 (2017)10.1103/PhysRevA.95.063817] that concurrent processes of optical rectification and multiphoton absorption of an ultrashort laser pulse in an electro-optic crystal can generate a quasistatic electromagnetic precursor propagating ahead of the laser pulse. The electric and magnetic fields in the precursor can exceed the fields in the ordinary terahertz wave generated behind the laser pulse. We propose a way to enhance the precursor's magnitude tremendously, by at least two orders of magnitude, by using tilted-pulse-front excitation technique and higher orders of multiphoton absorption. In particular, we show that a pulse of 500 fs duration and 70 GW/cm peak intensity from a Yb-doped laser amplifier can generate in a 5-mm-thick LiNbO crystal a 0.5-mm-long precursor with the strengths of the electric and magnetic fields as high as 0.4 MV/cm and 0.13 T, respectively. Strong quasistatic (subterahertz) fields can be a useful tool for particle acceleration, molecular orientation, ultrafast control of magnetic order in matter, and in terahertz streaking techniques.
最近有预测[M. I. 巴库诺夫、A. V. 马斯洛夫和M. V. 察列夫，《物理评论A》95，063817 (2017)10.1103/PhysRevA.95.063817]表明，在电光晶体中，超短激光脉冲的光学整流和多光子吸收的并发过程能够产生一个在激光脉冲之前传播的准静态电磁前驱波。该前驱波中的电场和磁场能够超过在激光脉冲之后产生的普通太赫兹波中的场强。我们提出了一种通过使用倾斜脉冲前沿激发技术和更高阶的多光子吸收，将前驱波的幅度极大地增强至少两个数量级的方法。特别地，我们表明，来自掺镱激光放大器的持续时间为500飞秒、峰值强度为70吉瓦/平方厘米的脉冲，能够在一块5毫米厚的铌酸锂晶体中产生一个长度为0.5毫米的前驱波，其电场和磁场强度分别高达0.4兆伏/厘米和0.13特斯拉。强准静态（亚太赫兹）场对于粒子加速、分子取向、物质中磁序的超快控制以及太赫兹条纹技术而言可能是一种有用的工具。
