中红外激光产生宏观高次谐波的理论研究

Theoretical study of macroscopic high-order harmonic generation driven by mid-IR 1500nm laser pulse

通过求解Maxwell方程模拟了中红外1 500nm强激光产生的宏观Xe气高次谐波谱.研究结果表明,气体靶位置对谐波场的强度具有非常重要的影响,与通常将气体靶放在激光焦斑之后相比,位于激光焦斑之前的气体靶产生高能光子的强度得到了很大程度的提高.分析表明,产生这种现象除了与激光场在介质中的演化有关外,还来源于谐波场在自由空间的传播性质,理论模拟与实验结果具有很好的一致性.

We simulate the macroscopic Xe high-order harmonic spectra generated by mid-IR 1 500 nm laserpulse. The simulations produce well the main experimental findings, i.e., the high-energy harmonicintensity can be enhanced when the gas jet is placed before the laser focus. Our analysis show that thisphenomenon not only resulting from propagation of laser pulse in the medium, but also related to thepropagation of harmonic field in the free space.