Ultrafast response of dielectric properties of monolayer phosphorene to femtosecond laser

Abstract

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” absorption 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 ultrafast electronics and optoelectronics.

Real-Time Exciton Dynamics with Time-Dependent Density-Functional Theory

“…RT-TDDFT for solids has a history of over two decades [9,10]. Besides the calculation of optical spectra, it has been used to simulate two-photon absorption and ultrafast dielectric response [11][12][13][14], coherent phonons and stimulated Raman scattering [15], ultrafast laserinduced metal-insulator transitions [16], nonlinear optical response and high-order harmonic generation [17][18][19], photoelectron spectroscopy [20], electronic stopping power [21,22], ultrafast demagnetization of ferromagnets and magnons [23,24], as well as core excitations [25][26][27].…”

“…In Refs. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25], (semi)local exchange-correlation (xc) functionals were used, i.e., the adiabatic local-density approximation (ALDA) or generalized gradient approximations (GGA). This causes a serious problem for semiconductors and insulators: (semi)local xc approximations cannot describe excitons [1,28], and therefore produce physically wrong optical absorption spectra.…”

Electron dynamics in extended systems within real-time time-dependent density functional theory

“…Local or semi-local approximations of exchange and correlation are most prevalent in applications of TDDFT to study the dynamics of interacting electrons. [16][17][18]42,43,83,[105][106][107][108][109][110] This typically means using the adiabatic local-density approximation (ALDA) or its generalized gradient approximation (GGA) extension, but in more recent works 111,112 also modern meta-GGA approximations such as the strongly constrained and appropriately normed (SCAN) functional 113,114 are employed within RT-TDDFT. More accurate and computationally tractable functionals are always desirable and specifically the influence of long-range corrections, selfinteraction errors, and the adiabatic approximation remains unexplored e.g.…”

Femtosecond Laser Micro/Nano-manufacturing: Theories, Measurements, Methods, and Applications

“…It has been proven theoretically that an increase in the delay time of a femtosecond laser pulse in the range of 10-30 fs will increase the number of exciting electrons and greatly improve the absorption efficiency of laser energy. Time-varying density functional calculations of the ultrafast kinetics of a phosphite monolayer irradiated by femtosecond laser have been carried out [16]. It was found that under femtosecond laser irradiation, the real part of the phosphonene dielectric function diverges negatively at low laser frequencies and the imaginary part exhibits a significant "quasi-exciton" absorption peak ( Fig.…”

“…Real (a, c) and imaginary (b, d) parts of the dielectric function of monolayer phosphorene excited by femtosecond laser with intensities of 10 12 W/cm 2 and 10 11 W/cm 2 . The real part of the dielectric function diverges negatively at low frequencies and a quasi-exciton absorption peak appears in the imaginary part [16] 1 3 in the molecular dynamics calculation simulation process greatly influences simulation accuracy. In the interaction between a femtosecond laser and a material, the Morse potential function is adopted for considering the short-range van der Waals force [17].…”