Vampa G, McDonald C R, Orlando G, Klug D D, Corkum P B, Brabec T
Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada.
Phys Rev Lett. 2014 Aug 15;113(7):073901. doi: 10.1103/PhysRevLett.113.073901. Epub 2014 Aug 13.
We investigate theoretically high-harmonic generation (HHG) in bulk crystals exposed to intense midinfrared lasers with photon energies smaller than the band gap. The two main mechanisms, interband and intraband HHG, are explored. Our analysis indicates that the interband current neglected so far is the dominant mechanism for HHG. Saddle point analysis in the Keldysh limit yields an intuitive picture of interband HHG in solids similar to atomic HHG. Interband and intraband HHG exhibit a fundamentally different wavelength dependence. This signature can be used to experimentally distinguish between the two mechanisms in order to verify their importance.
我们从理论上研究了在光子能量小于带隙的强中红外激光作用下块状晶体中的高次谐波产生（HHG）。探讨了两种主要机制，即带间和带内高次谐波产生。我们的分析表明，迄今为止被忽略的带间电流是高次谐波产生的主导机制。在Keldysh极限下的鞍点分析给出了固体中带间高次谐波产生的直观图像，类似于原子高次谐波产生。带间和带内高次谐波产生表现出根本不同的波长依赖性。这一特征可用于实验区分这两种机制，以验证它们的重要性。
