Coherent Bloch Oscillations in Superlattices Excited by 1.55-micrometer fs-Laserpulses
Abstract
The aim of this project is the investigation of coherent Bloch oscillations in superlattices excited by fs optical pulses in the 1.55 microns wavelength range. One potential application of Bloch oscillations is the electromagnetic radiation emitted from this system tunable from several hundred GHz to some THz by changing the voltage applied to the superlattice. The investigations were performed by fs optical pump-probe spectroscopy in strain-balanced InGaAs(P) based heterostructures grown by MOVPE. Bloch oscillations have been observed for the first time in ternary InGaAs/InGaAs superlattices at low lattice temperatures. The dephasing time of the oscillations was found to be only a factor of 3 smaller compared to the mature GaAs/AlGaAs material system grown by MBE. It could be observed that the oscillation frequency changes in time. The analysis of this effect has lead to important insights into the transport and scattering dynamics in this material on the sub-picosecond time scale. It was found that scattering with thermally populated LO phonons is a limiting factor for the room temperature operation Bloch oscillations. The obtained results give important hints for the further optimization of the superlattices concerning material composition and device design.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1999
- Accession Number
- ADA362349
Entities
People
- Heinrich Kurz
- Michael Foerst
- Thomas Dekorsy