Dynamic Franz-Keldysh effect: excitonic versus free-carrier excitation schemes.
We theoretically investigate the dynamic Franz-Keldysh effect for subpicosecond optical pulses on quantum wells as a function of detuning from the bandgap. For specific spectral excitation regimes we find dramatic nonlinear enhancement effects that are due to the preferential creation of terahertz- (THz-) field-driven propagating excitons and free electron-hole pairs in the THz and the optical domains, respectively. Our results explain why previous measurements of THz sidebands in the optical domain were so weak; we suggest and demonstrate a remarkably better experiment.
Hughes
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Citrin
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