Interaction between two Bloch oscillating electron groups in a biased semiconductor superlattice created by a pair of temporally shifted optical pulses

Abstract

Abstract We investigate the interaction between two Bloch oscillating electron groups in a GaAs-based superlattice created by a pair of temporally shifted optical pulses, observing terahertz waveforms emitted by the second group in the presence of the first group. The terahertz emission exhibits gradual reductions in its resonance frequency and dephasing time as the temporal difference increases to a few hundred ps. This suggests that the first group interacts with the second group mainly via field screening and phonons. The initial oscillation phase of the second group, corresponding to its inversionless terahertz gain, is not affected by the first group.