Abstract
Over the past decades, the interaction between femtosecond intense lasers and semiconductors or dielectrics has been attracting significant attention as for high harmonic generation [1], high-quality laser micromachining without the thermal damage [2]. Several experimental and theoretical studies have reported that the use of two-color laser pulses enables highly efficient laser ablation of transparent materials compared to a single-color pump pulse [3,4]. In the present work, to elucidate how two-color femtosecond laser pulses deposit energy to electrons in semiconductors and dielectrics, we utilize the time-dependent density functional theory (TDDFT) and examine the energy absorption of crystalline silicon under overlapped two-color [ultraviolet (UV) and infrared (IR)] intense femtosecond laser pulses as a function of relative intensity with the total fluence conserved. The deposited energy is dramatically enhanced by two-color laser field and maximized when they are equally mixed [see Fig. 1 (a)]. The interplay between intraband electron motion in the valence band (before excitation) driven by the IR component and resonant valence-to-conduction interband excitation (carrier injection) induced by the UV component is identified as the underlying mechanism. Interestingly, the former plays an influential role, increases the excited electrons [see Fig. 1 (b)]. The effect of multiple multiphoton absorption paths, relative phase of carrier waves, or intraband motion of the created carriers in the conduction band play a minor role.
© 2023 IEEE
PDF ArticleMore Like This
Juraj Sladek, Yoann Levy, and Thibault J.-Y. Derrien
cm_5_4 The European Conference on Lasers and Electro-Optics (CLEO/Europe) 2023
L. Barilleau, G. Duchateau, B. Chimier, N. Fedorov, G. Geoffroy, and V. T. Tikhonchuk
EI_P_1 European Quantum Electronics Conference (EQEC) 2015
Eiyu Gushiken, Mizuki Tani, and Kenichi L. Ishikawa
cm_p_8 The European Conference on Lasers and Electro-Optics (CLEO/Europe) 2023