AbstractThe absorption of phase‐related near‐infrared fundamental (ω) and second harmonic (2ω) femtosecond pulses results in ballistic electrical currents in clean bulk silicon at room temperature. The ultrafast charge motion is directly monitored via a time‐resolved analysis of the emitted THz bursts of radiation. The vector direction of the current is precisely controlled by the polarization of the two‐color pump field and the relative phase ΔΦ = 2Φω – Φ2ω . The current generation process relies on a third order optical nonlinearity. Microscopically, current injection can be understood as arising from the quantum interference of one‐ and two‐photon absorption processes. Surprisingly, the efficiency of the current injection is relatively high despite the multitude of possible phonon‐assisted absorption channels in the multi‐valley band structure. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)