  We propose an all-optical method to directly reconstruct the band structure
of semiconductors. Our scheme is based on the temporal Young's interferometer
realized by high harmonic generation (HHG) with a few-cycle laser pulse. As a
time-energy domain interferometric device, temporal interferometer encodes the
band structure into the fringe in the energy domain. The relation between the
band structure and the emitted harmonic frequencies is established. This
enables us to retrieve the band structure from the HHG spectrum with a
single-shot measurement. Our scheme paves the way to study matters under
ambient conditions and to track the ultrafast modification of band structures.
