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Measurement of Coherence Decay in GaMnAs Using Femtosecond Four-wave Mixing
Published on: December 3, 2013
Coupled bloch-phonon oscillations in semiconductor superlattices
Physical Review Letters
|September 16, 2000
Summary
We observed direct coupling between Bloch oscillations and LO phonons in GaAs superlattices. This enables efficient, coherent phonon excitation at lower densities than in bulk materials.
Area of Science:
- Solid State Physics
- Quantum Mechanics
- Materials Science
Background:
- Coherent Bloch oscillations are a quantum transport phenomenon in semiconductor superlattices.
- Optical phonons, specifically longitudinal optical (LO) phonons, play a crucial role in electron-phonon interactions.
- GaAs/AlxGa1-xAs superlattices offer tunable electronic properties.
Purpose of the Study:
- To investigate the coupling between Bloch oscillations and LO phonons in GaAs/AlxGa1-xAs superlattices.
- To explore the conditions for resonant coupling where miniband widths exceed optical phonon energy.
- To determine the feasibility of using Bloch oscillations for coherent LO phonon excitation.
Main Methods:
- Experimental investigation of coherent Bloch oscillations in GaAs/AlxGa1-xAs superlattices.
- Tuning the Bloch frequency into resonance with the optical phonon energy.
- Observing the direct coupling and coherent excitation of LO phonons.
- Theoretical modeling to confirm experimental findings.
Main Results:
- Direct coupling between Bloch oscillations and LO phonons was observed near resonance.
- Coherent excitation of LO phonons via Bloch oscillations was achieved.
- The required density for driving coherent LO phonons was significantly lower (by ~2 orders of magnitude) compared to bulk GaAs.
- Experimental results were validated by theoretical calculations.
Conclusions:
- GaAs/AlxGa1-xAs superlattices facilitate resonant coupling between Bloch oscillations and LO phonons.
- Bloch oscillations provide an efficient pathway for coherent LO phonon excitation at reduced densities.
- This phenomenon opens possibilities for novel optoelectronic devices and quantum control applications.
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