Direct acoustic phonon excitation by intense and ultrashort terahertz pulses

We report on the direct and resonant excitation of acoustic phonons in an AlGaAs intrinsic semiconductor using intense coherent and single cycle terahertz pulses created by two-color femtosecond laser pulse filamentation in air. While the electrons are left unperturbed, we follow the lattice dynamics with time-delayed optical photons tuned to the interband transition. (C) 2010 American Institute of Physics. [doi:10.1063/1.3529466]