Nonperturbative interband response of a bulk InSb semiconductor driven off resonantly by terahertz electromagnetic few-cycle pulses.
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.
Department of Physics and Center for Applied Photonics, University of Konstanz, Universitätsstr. 10, 78457 Konstanz, Germany.
F
F
Junginger
B
B
Mayer
C
C
Schmidt
O
O
Schubert
S
S
Mährlein
A
A
Leitenstorfer
R
R
Huber
A
A
Pashkin