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30 May 2003 Ultrafast coherent and incoherent dynamics of intersubband excitations in semiconductor quantum wells
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Proceedings Volume 4992, Ultrafast Phenomena in Semiconductors VII; (2003)
Event: Integrated Optoelectronics Devices, 2003, San Jose, CA, United States
The generation, manipulation and relaxation of optical intersubband excitations in n-type GaAs/AlGaAs and p-type SiGe/Si quantum wells are studied by different techniques of ultrafast spectroscopy in the mid-infrared. For electrons in GaAs/AlGaAs quantum wells, femtosecond time-resolved four-wave-mixing studies demonstrate de-phasing times of coherent intersubband polarizations of several hundreds of femtoseconds which are determined by electron-electron scattering. The measured dephasing times fully account for the width of the stationary intersubband absorption line, giving evidence of a predominant homogeneous broadening. Using phase-locked mid-infrared pulses and phase-resolving detection schemes, coherent optical control of such intersubband polarizations is demonstrated. In a second experiment, we study the intersubband relaxation of heavy holes (HH) in p-type SiGe/Si quantum wells. Intersubband scattering from the HH2 back to the HH1 subband occurs with a time constant of 250 fs determined by scattering with optical phonons through the deformation potential interaction.
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Thomas Elsaesser, Robert A. Kaindl, Felix Eickemeyer, Klaus Reimann, Michael Woerner, R. Hey, Christian Miesner, Karl Brunner, and Gerhard Abstreiter "Ultrafast coherent and incoherent dynamics of intersubband excitations in semiconductor quantum wells", Proc. SPIE 4992, Ultrafast Phenomena in Semiconductors VII, (30 May 2003);

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