171107-4 , 2017-10 , American Institute of Physics
We calculate the electron excitation in cubic silicon carbide (3C-SiC) caused by the intense femtosecond laser double pulses using time-dependent density functional theory (TDDFT). After the first pulse ends, excited electrons should be relaxed by the collisional processes.Because TDDFT dose not include the scattering processes, the thermalization is mimicked by following three assumptions. First, we assume no collisions and relaxation processes. Second, we assume the partially thermalized electronic state defined by two quasi-temperatures in the conduction and valence bands individually. Third, we assume the thermalized electron distribution, which is expressed by single electron temperature. Our results indicate that the plasma frequency formed by the first pulse is the key parameter in energy absorption in the second pulse. When the plasma frequency is comparable to the frequency of the laser, the energy absorption in the second pulse shows maximum. The lower electron temperature shows higher plasma frequency and higher efficient energy absorption, because the effective mass of electron becomes smaller.