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In the last few years, the interaction of terahertz (THz) radiation with many-electron systems in semiconductors, metals, graphene, or other materials has attracted significant attention worldwide. After our original suggestion to used THz radiation to identify excitonic populations in semiconductors, our group proceeded to developed a microscopic many-body approach that allows us to quantitatively...
The exciton binding energy in GaAs-based quantum-well (QW) structures is in the range of ~10 meV, which falls in the terahertz (THz) regime. THz-induced nonlinear optical effects of excitons in QWs are of great interest because they provide new insights into the quantum coherence and wavepacket dynamics in semiconductors. This paper presents a time-resolved study to observe resonant interactions of...
Ultrafast carrier dynamics of Ge/SiGe quantum wells grown on a Si substrate are investigated using pump-probe spectroscopy. Optical gain and population inversion are obtained on a femtosecond time scale. A microscopic theory supports the results.
The paper presents a theoretical analysis of the nonlinear THz response from the internal transitions of coherent and incoherent excitons based on the formulated microscopic THz theory. Moreover, the response of unexcited semiconductors to extremely intense THz fields is investigated .The intersubband transitions of optically excited quantum wells using linear THz spectroscopy is also studied. The...
By combining coherent control schemes and photoelectron spectroscopy it is possible to generate ultrafast current pulses at surfaces and in solids and to detect their decay directly in momentum space with femtosecond time resolution.
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