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Nonlinear terahertz response of -type GaAs
1Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany.
Physical Review Letters
|May 23, 2006
Summary
Intense terahertz pulses excite coherent 2 THz emission in n-type GaAs. This emission decays over picoseconds, explained by a quantum model of disordered impurity transitions, not just free electron behavior.
Area of Science:
- Solid State Physics
- Quantum Mechanics
- Terahertz Spectroscopy
Background:
- Ultrafast terahertz (THz) pulses can induce nonlinear optical phenomena in semiconductors.
- Understanding carrier dynamics and impurity interactions is crucial for novel electronic devices.
Purpose of the Study:
- To investigate the coherent THz emission from n-type Gallium Arsenide (GaAs) excited by ultrashort THz pulses.
- To elucidate the underlying mechanisms governing the nonlinear THz response at room temperature.
Main Methods:
- Phase-resolved nonlinear propagation experiments using intense ultrashort THz pulses.
- Analysis of THz emission and decay dynamics.
- Development and application of a quantum mechanical discrete state model.
Main Results:
- Observed coherent 2 THz emission from n-type GaAs.
- Measured a picosecond decay of the emitted field, contrasting with ultrafast carrier-carrier scattering.
- Linear THz response matched the Drude model for free electrons.
- Nonlinear response dominated by super-radiant decay of optically inverted impurity transitions.
Conclusions:
- The observed nonlinear THz response is primarily due to the super-radiant decay of impurity transitions.
- A quantum mechanical model incorporating disordered impurity potentials accurately explains the experimental findings.
- This study highlights the role of impurity states in the THz response of semiconductors.
