Ultrafast response of dielectric properties of monolayer phosphorene to femtosecond laser

摘要

Phosphorous consisting of only a few layers, or phosphorene, is a two-dimensional material with high carrier mobility and a useful and adjustable band gap. In this paper, we studied the ultrafast response of the dielectric properties of monolayer phosphorene to femtosecond laser pulses by employing the time-dependent density functional theory. The simulation results showed that, as a result of femtosecond laser irradiation, the dielectric function of monolayer phosphorene exhibited a negative divergence of its real part at low frequency and a remarkable "quasi-exciton" absoφtion peak of its imaginary part. We inferred that this type of response was induced by electron-hole pairs excited by the femtosecond laser. Moreover, we showed how the degrees of freedom (intensity and polarization) of the laser pulse could be helpful for the manipulation of the system transient response. The anisotropic dielectric response of monolayer phosphorene was also observed. Our work revealed the potential applications of monolayer phosphorene for ultra-fast electronics and optoelectronics.