In the investigation of the nonequilibrium ultrafast dynamics of the coherent phonon-plasmon coupled modes in a polar semiconductor, we predict theoretically that their coherent oscillations can be efficiently controlled by using the pulse train of below-band-gap excitation. The dynamics of the coherent modes are driven by the virtual electron-hole pairs, which would avoid dephasing sources such as accumulation of photoexcited charges and spontaneous emission. This implies that carrier mobility can also be efficiently controlled and dramatically enhanced by synchronizing the pulse train with the coherent oscillation of the carrier-relevant coupled mode.

• Received 23 June 2008

DOI:https://doi.org/10.1103/PhysRevLett.101.235501