Controlling ultrafast currents by the nonlinear photogalvanic effect. (21st December 2015)

• Record Type: Journal Article
• Authors: Wachter, Georg; Sato, Shunsuke A; Floss, Isabella; Lemell, Christoph; Tong, Xiao-Min; Yabana, Kazuhiro; Burgdörfer, Joachim
• Is Part Of: New journal of physics. Volume 17:Number 12(2015:Dec.)
• Publication Date: 2015-12-21
• Subjects: ultrafast current -- photogalvanic effect -- TDDFT -- SiO2; 42.50.Hz -- 42.65.Re -- 42.65.Pc -- 78.47.J-; Physics -- Periodicals; Physics; Periodicals; 530.05
• DOI: 10.1088/1367-2630/17/12/123026
• Languages: English
• ISSNs: 1367-2630

Abstract

Abstract: We investigate the effect of broken inversion symmetry on the generation and control of ultrafast currents in a transparent dielectric (SiO2 ) by strong femtosecond optical laser pulses. Ab initio simulations based on time-dependent density functional theory predict ultrafast direct currents that can be viewed as a nonlinear photogalvanic effect. Most surprisingly, the direction of the current undergoes a sudden reversal above a critical threshold value of laser intensity of about W cm −2 . We trace this switching to the transition from nonlinear polarisation currents to the tunnelling excitation regime. The latter is found to be sensitive to the relative orientation between laser polarisation and chemical bonds. We demonstrate control of the ultrafast currents by the time delay between two laser pulses. While two temporally separated laser pulses lead to currents along one direction their temporal overlap can reverse the current. We find the ultrafast current control by the nonlinear photogalvanic effect to be remarkably robust and insensitive to the laser-pulse shape and the carrier-envelope phase.