Nonperturbative Interband Response of a Bulk InSb Semiconductor Driven Off Resonantly by Terahertz Electromagnetic Few-Cycle Pulses.

Department of Physics and Center for Applied Photonics, University of Konstanz, Universitätsstr. 10, 78457 Konstanz, Germany.
Physical Review Letters (Impact Factor: 7.73). 10/2012; 109(14):147403. DOI: 10.1103/PhysRevLett.109.147403
Source: PubMed

ABSTRACT Intense multiterahertz pulses are used to study the coherent nonlinear response of bulk InSb by means of field-resolved four-wave mixing spectroscopy. At amplitudes above 5  MV/cm the signals show a clear temporal substructure which is unexpected in perturbative nonlinear optics. Simulations based on a model of a two-level quantum system demonstrate that in spite of the strongly off-resonant character of the excitation the high-field few-cycle pulses drive the interband resonances into a nonperturbative regime of Rabi flopping. The rotating wave approximation breaks down in this case and the system reaches a complete population inversion.

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