We report on the observation of two-photon absorption for the direct gap in intrinsic germanium at room temperature using two independently tunable picosecond, mid-infrared light pulses. The two-photon absorption coefficient is determined for different wavelengths, and carrier densities down to about1013 cm−3could be detected at a sample length of 700 &mgr;m. Two-photon absorption in germanium is demonstrated to be a versatile tool for zero-point determination in time resolved pump-probe investigations and permits a precise measure of the time resolution of the laser system. ©1997 American Institute of Physics.