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We observe a strong ultrafast AC Stark shift of the direct band transition in strained germanium quantum wells grown on silicon. At 150 meV, the maximum measured blue shift of the band edge is one order of magnitude larger than typically found in III-V materials [1]. The power dependence shows a linear behavior between the electrical field intensity and the magnitude of the shift which is in good...
We use second harmonic generation to observe an ultrafast magnetic phase transition in MnAs near room temperature following excitation by a 300 fs optical pulse; transition times are on the order of 10 ps.
The ultrafast carrier dynamics of Ge/SiGe quantum wells on Si substrate are investigated by pump-probe spectroscopy. Pronounced nonequilibrium effects in the relaxation dynamics and transient gain are observed and analyzed using a microscopic many-body theory.
Ga(NAsP) multi quantum well heterostructures were grown pseudomorphically on exactly oriented (001) silicon substrates without the formation of misfit dislocations. Optical pumped lasing operation was observed at temperatures up to 125 K.
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.
Ultrafast carrier relaxation of Ge/SiGe quantum wells grown on a Si substrate are investigated using pump-probe spectroscopy. A nonthermal carrier distribution is observed. The corresponding inter- and intra-valley scattering times are deduced.
We report lasing of optically pumped Ga(NAsP)/(BGa)(AsP) heterostructures grown lattice-matched on Si. Modal gain of up to 80 cm-1 is determined at 300 K and a distinct threshold behaviour and mode spectrum is observed up to 100 K.
We significantly improve the dynamics of a vertical-cavity surface-emitting laser by using chirped rather than bandwidth-limited optical excitation. The optimal excitation pulse is found by a genetic algorithm in a learning loop.
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