Quantum Physics With Ultrabroadband and Intense Terahertz Pulses

Abstract-We present recent advances in the generation of highly intense multiterahertz transients and their application to nonlinear spectroscopy of bulk semiconductors. An optimized scheme of parametric amplification results in broadband single-or few-cycle terahertz transients with peak electric fields up to 10 or 2S MV/cm, respectively. Time-resolved four-wave mixing tera-hertz spectroscopy of [nSb far away from the interband resonance demonstrates clear signatures of a nonperturbative regime ofRabi flopping. We qualit.'ltively explain the observed behavior within a model of a quantum two-level system. [n addition, we demonstrate the dynamical Franz-KeJdysh effect in InP resolved on a subcycle timescale. The field-induced modulation of the interband optical absorption at the second harmonic of the driving terahertz field is observed in full agreement with theoretical predictions. Index 1erms-EJectrooptic elTects, four-wave mixing, nonlinear optics, semiconductor materials, teraltertz technology, ultrafast optics. 1