Influence of external electric field on laser- induced wave process occurring in semiconductor under the femtosecond pulse acting

摘要

We analyze laser-induced periodic structures developing in a semiconductor under both femtosecond pulse acting and external electric field action. These structures are appeared due to optical Instability appearance, which is caused by nonlinear dependence of semiconductor absorption coefficient from charged particles concentration. Dependence of the semiconductor absorption is induced as by the Fermi energy level renormalization so by the Burstein-Moss effect. The electron mobility, electron diffusion, and laser-induced electric field are taken into account for laser pulse propagation analyzing in semiconductor. We found out that an external electric field causes complicated motion of high absorption domain in a semiconductor. In certain cases, it causes drops developing of charged particles. External electric field acting can result in helical structures appearing of high concentration of generated charged particles. Moreover, under the action of the external electric field one can expect developing of chaotic spatio-temporal structure of charged particles which will induce chaotic changing of time-dependent optical radiation distribution. In turn, such spatio-temporal structures generate electro-magnetic waves with complicated pulse shape and spatial profile. It may be important at generation of the THz radiation because it changes the radiation generation direction. We discuss also briefly the finite-difference schemes, which can be used for computer simulation of the problem under consideration.