Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

physica status solidi (b)

Dynamics of the Amplitude, Phase and Polarization State of Coherent Emission from Quantum Wells

Arthur L. Smirl, Wojciech J. Walecki, Xiayuan Chen, Osvaldo Buccafusca

Published Nov 1, 1997• 6 citations
Publisher

Abstract

A dual-channel version of spectral interferometry is used to completely characterize the extremely weak ultrashort coherent four wave mixing (FWM) emission from multiple quantum wells (MQWs) by time resolving the polarization state, as well as the scalar amplitude and phase. The amplitudes and the phases of the x and y components of the coherent FWM emission are found to exhibit systematic (but distinct) variations with excitation fluence, time delay between the two incident pulses, detuning of the laser wavelength from the heavy hole (hh) exciton, and the orientation of the input polarizations. From these, a self consistent picture of the temporal dynamics of the amplitude, phase and polarization state is obtained that delineates the roles of many body effects, such as local field corrections, excitation-induced dephasing and biexcitons, in determining the excitonic dynamics.

DOI
10.1002/1521-3951(199711)204:1<16::aid-pssb16>3.0.co;2-7

Related papers

Temporally and spectrally resolved amplitude and phase of coherent four-wave-mixing emission from GaAs quantum wells

X. Chen, Wojciech J. Walecki, Osvaldo Buccafusca +2 more

We demonstrate that spectral interferometry can be used together with a well-characterized reference pulse to directly determine the spectral amplitude and spectral phase of coherent four-wave-mixing (FWM) emission from multiple quantum wells. The temporal amplitude and phase are then readily obtained by an inverse Fourier transformation. We illustrate that it is necessary to accurately determine the spectral phase, as well as the spectral amplitude, in order to correctly determine the temporal behavior. We subsequently use this technique to measure discontinuities in the temporal phase. Instabilities in the phase occur and phase jumps of $\ensuremath{\sim}\ensuremath{\pi}$ are produced when both the real and imaginary parts of the FWM field are zero. These jumps occur at the minima in the quantum beats, and this condition requires the excitation of approximately equal numbers of heavy- and light-hole excitons.

Physical review. B, Condensed matter•Oct 15, 1997•23 citations

Heavy-hole and light-hole quantum beats in the polarization state of coherent emission from quantum wells

Arthur L. Smirl, Xi Chen, Osvaldo Buccafusca

Dual-channel spectral interferometry is used to measure the vectorial dynamics of the the four-wave-mixing signal from a GaAs-AlGaAs multiple quantum well when both heavy-and light-hole excitons are excited. The ellipticity, the orientation, and the sense of rotation of the polarization ellipse associated with this emission are observed to oscillate dramatically at the heavy-hole-light-hole quantum beat frequency. The qualitative nature of the beating can be described by a simple model based on the density matrix equations for two independent three-level systems without the inclusion of many body effects; however, these beats are superposed on a polarization that is dominated by many-body effects.

IEEE Journal of Quantum Electronics•Apr 1, 1999•11 citations

Excitation-Induced Phase Shifts of Heavy and Light Hole Quantum Beats in Multiple Quantum Wells

Wei E. I. Sha, A. E. Paul, Shekhar Patkar +1 more

In recent years, transient four-wave mixing (FWM) techniques have been used to investigate the dephasing times of non-equilibrium carriers in semiconductor heterostructures by monitoring the decay of the macroscopic polarization. Initially, this decay was measured by temporally-integrating the scattered FWM signal as a function of time delay between two (or more) pump pulses. More recently, the macroscopic polarization decay has been measured by time-resolving the FWM signal by cross correlating it with an ultrashort laser pulse via frequency up-conversion in a nonlinear crystal. When excitons with slightly different energies are excited, oscillations (or beats) have been observed both in the time-integrated FWM signal and in the time-resolved FWM signal. Such beats have been observed, for example, between light- and heavy-hole excitons and between excitons in wells of different widths. Both the spectral behavior1 of the time-integrated FWM signal and the temporal behavior2 of the time-resolved signal have been shown to allow the distinction between the polarization interference associated with two independent oscillators and the quantum beats associated with two coupled oscillators which share a common level. In addition, it has been demonstrated3 that the quantum beats produced by incident pulses with parallel polarizations are exactly out of phase (by π) with the beats produced by orthogonally polarized pulses. In each case1-3, the period and phase of the beats and the polarization of FWM signal were explained by using a six-level model, which excluded many-body effects, to describe the J=1/2 conduction and J=3/2 valence states. Within the last few months, however, it has been shown that a complete description of the polarization selection rules for the FWM signal requires excitation-induced dephasing4 or disorder-induced coupling of the σ + and σ – excitonic transitions5.

International Conference on Ultrafast Phenomena•Jan 1, 1994•0 citations

Coherent exciton dynamics : time-resolved polarimetry

Arthur L. Smirl

The studies described in this chapter convince the reader that time-resolved polarimetry is an extremely sensitive way to study many body effects. The vectorial dynamics contain useful information about many-body effects, quantum interference and optical anisotropies that would be difficult to obtain in any other way. The chapter begins with a brief review of some of the four-wave-mixing (FWM) techniques that have been most commonly used to measure the coherent emission from multiple quantum wells (MQWs). The ellipticity and the fraction of unpolarised light are both significantly smaller for the negative delay. These features provide additional tests for any proposed model that purports to describe coherent excitonic dynamics in MQWs. The chapter discusses the treatment of excitons in semiconductors as two-level systems, and follows with a detailed review of the solutions to the density matrix equations for two independent two-level systems, with an emphasis on the vectorial nature of the FWM emission from such systems.

CRC Press eBooks•Dec 5, 2020•0 citations

Ultrafast coherent dynamics of excitons of higher-order subbands in semiconductor quantum wells

S. Arlt, U. Siegner, François Morier-Genoud +1 more

The coherent emission from excitons corresponding to different subband transitions in a 500 Åbroad GaAs/AlGaAs quantum well is studied by spectrally resolved transient four-wave mixing (FWM). For the simultaneous excitation of several subband transitions, the dephasing times of the lowest exciton and higher- order exciton transitions are determined from the width of the resonances in the FWM spectrum. The decay of the spectrally integrated FWM signal as a function of the time delay between the excitation laser pulses does not reflect the dephasing times but is determined by the laser pulse width for multi-subband excitation. This is indicative of quantum interference between exciton and continuum transitions. Many-body Coulomb effects have to be included in a theoretical treatment of these experimental observations.

Radiative Processes and Dephasing in Semiconductors•Jan 1, 1998•0 citations

Heavy-hole and light-hole oscillations in the coherent emission from quantum wells: Evidence for exciton-exciton correlations

Arthur L. Smirl, Martin J. Stevens, Xi Chen +1 more

We demonstrate the presence of strong exciton-exciton correlations in GaAs-AlGaAs multiple quantum wells by using the polarization selection rules for four-wave mixing and a test that was originally designed to distinguish between quantum beats and polarization interference. We show that, when the four-wave-mixing signal is produced by two pulses that have the same circular polarization, dynamic beating behavior is observed at the heavy-hole-light-hole frequency that provides evidence of Coulomb-induced correlations that go beyond those expected from the semiconductor Bloch equations in the Hartree-Fock approximation and beyond the local field corrections used in simple phenomenological models. Moreover, this behavior cannot be explained by invoking biexcitonic effects. We demonstrate that this dynamic excitonic coupling can be explained in terms of a competition between quantum-beat-like and polarization-interference-like behavior, and we show that such behavior can be used to place quantitative limits on the coupling strength. In addition, we use a simple phenomenological model to show that excitation-induced-dephasing can produce such correlations.

Physical review. B, Condensed matter•Sep 15, 1999•45 citations
A dual-channel version of spectral interferometry is used to completely characterize the extremely weak ultrashort coherent four wave mixing (FWM) emission from multiple quantum wells (MQWs) by time resolving the polarization state, as well as the scalar amplitude and phase. The amplitudes and the phases of the x and y components of the coherent FWM emission are found to exhibit systematic (but distinct) variations with excitation fluence, time delay between the two incident pulses, detuning of the laser wavelength from the heavy hole (hh) exciton, and the orientation of the input polarizations. From these, a self consistent picture of the temporal dynamics of the amplitude, phase and polarization state is obtained that delineates the roles of many body effects, such as local field corrections, excitation-induced dephasing and biexcitons, in determining the excitonic dynamics.
We demonstrate that spectral interferometry can be used together with a well-characterized reference pulse to directly determine the spectral amplitude and spectral phase of coherent four-wave-mixing (FWM) emission from multiple quantum wells. The temporal amplitude and phase are then readily obtained by an inverse Fourier transformation. We illustrate that it is necessary to accurately determine the spectral phase, as well as the spectral amplitude, in order to correctly determine the temporal behavior. We subsequently use this technique to measure discontinuities in the temporal phase. Instabilities in the phase occur and phase jumps of $\ensuremath{\sim}\ensuremath{\pi}$ are produced when both the real and imaginary parts of the FWM field are zero. These jumps occur at the minima in the quantum beats, and this condition requires the excitation of approximately equal numbers of heavy- and light-hole excitons.
Dual-channel spectral interferometry is used to measure the vectorial dynamics of the the four-wave-mixing signal from a GaAs-AlGaAs multiple quantum well when both heavy-and light-hole excitons are excited. The ellipticity, the orientation, and the sense of rotation of the polarization ellipse associated with this emission are observed to oscillate dramatically at the heavy-hole-light-hole quantum beat frequency. The qualitative nature of the beating can be described by a simple model based on the density matrix equations for two independent three-level systems without the inclusion of many body effects; however, these beats are superposed on a polarization that is dominated by many-body effects.
In recent years, transient four-wave mixing (FWM) techniques have been used to investigate the dephasing times of non-equilibrium carriers in semiconductor heterostructures by monitoring the decay of the macroscopic polarization. Initially, this decay was measured by temporally-integrating the scattered FWM signal as a function of time delay between two (or more) pump pulses. More recently, the macroscopic polarization decay has been measured by time-resolving the FWM signal by cross correlating it with an ultrashort laser pulse via frequency up-conversion in a nonlinear crystal. When excitons with slightly different energies are excited, oscillations (or beats) have been observed both in the time-integrated FWM signal and in the time-resolved FWM signal. Such beats have been observed, for example, between light- and heavy-hole excitons and between excitons in wells of different widths. Both the spectral behavior1 of the time-integrated FWM signal and the temporal behavior2 of the time-resolved signal have been shown to allow the distinction between the polarization interference associated with two independent oscillators and the quantum beats associated with two coupled oscillators which share a common level. In addition, it has been demonstrated3 that the quantum beats produced by incident pulses with parallel polarizations are exactly out of phase (by π) with the beats produced by orthogonally polarized pulses. In each case1-3, the period and phase of the beats and the polarization of FWM signal were explained by using a six-level model, which excluded many-body effects, to describe the J=1/2 conduction and J=3/2 valence states. Within the last few months, however, it has been shown that a complete description of the polarization selection rules for the FWM signal requires excitation-induced dephasing4 or disorder-induced coupling of the σ + and σ – excitonic transitions5.
The studies described in this chapter convince the reader that time-resolved polarimetry is an extremely sensitive way to study many body effects. The vectorial dynamics contain useful information about many-body effects, quantum interference and optical anisotropies that would be difficult to obtain in any other way. The chapter begins with a brief review of some of the four-wave-mixing (FWM) techniques that have been most commonly used to measure the coherent emission from multiple quantum wells (MQWs). The ellipticity and the fraction of unpolarised light are both significantly smaller for the negative delay. These features provide additional tests for any proposed model that purports to describe coherent excitonic dynamics in MQWs. The chapter discusses the treatment of excitons in semiconductors as two-level systems, and follows with a detailed review of the solutions to the density matrix equations for two independent two-level systems, with an emphasis on the vectorial nature of the FWM emission from such systems.
The coherent emission from excitons corresponding to different subband transitions in a 500 Åbroad GaAs/AlGaAs quantum well is studied by spectrally resolved transient four-wave mixing (FWM). For the simultaneous excitation of several subband transitions, the dephasing times of the lowest exciton and higher- order exciton transitions are determined from the width of the resonances in the FWM spectrum. The decay of the spectrally integrated FWM signal as a function of the time delay between the excitation laser pulses does not reflect the dephasing times but is determined by the laser pulse width for multi-subband excitation. This is indicative of quantum interference between exciton and continuum transitions. Many-body Coulomb effects have to be included in a theoretical treatment of these experimental observations.
We demonstrate the presence of strong exciton-exciton correlations in GaAs-AlGaAs multiple quantum wells by using the polarization selection rules for four-wave mixing and a test that was originally designed to distinguish between quantum beats and polarization interference. We show that, when the four-wave-mixing signal is produced by two pulses that have the same circular polarization, dynamic beating behavior is observed at the heavy-hole-light-hole frequency that provides evidence of Coulomb-induced correlations that go beyond those expected from the semiconductor Bloch equations in the Hartree-Fock approximation and beyond the local field corrections used in simple phenomenological models. Moreover, this behavior cannot be explained by invoking biexcitonic effects. We demonstrate that this dynamic excitonic coupling can be explained in terms of a competition between quantum-beat-like and polarization-interference-like behavior, and we show that such behavior can be used to place quantitative limits on the coupling strength. In addition, we use a simple phenomenological model to show that excitation-induced-dephasing can produce such correlations.