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

Physical review. B, Condensed matter

Nanoroughness localization of excitons in GaAs multiple quantum wells studied by transient four-wave mixing

D. Birkedal, Vadim G. Lyssenko, K.‐H. Pantke, John Erland, J. M. Hvam

Published Mar 15, 1995• 12 citations
Publisher

Abstract

The interface roughness on a nanometer scale plays a decisive role in dephasing of excitons in GaAs multiple quantum wells. The excitonic four-wave mixing signal shows a free polarization decay and a corresponding homogeneously broadened line from areas with interface roughness on a scale larger than the exciton diameter. A photon echo and a corresponding inhomogeneously broadened line are observed from areas of interface roughness on a scale less than the exciton diameter. In the present study we observe both mechanisms simultaneously, and are able to clearly distinguish between the two mechanisms by spectrally resolving the transient four-wave-mixing signal.

DOI
10.1103/physrevb.51.7977

Related papers

Ultrafast nonlinear optics in GaAs/AlGaAs quantum wells

J. M. Hvam, D. Birkedal, Vadim G. Lyssenko +2 more

By degenerate four-wave mixing experiments in a two-beam geometry, we have investigated the initial coherence and dephasing of quasi two-dimensional excitions and biexcitons in GaAs multiple quantum wells. The dephasing has contributions from phonon scattering, interface-roughness scattering and exciton-exciton scattering. Inhomogeneous broadening and generation of coherent wavepackets play a significant role in the coherent exciton dynamics. The incoherent exciton dynamics, diffusion and recombination, is studied by three-beam transient grating experiments. A significant difference in the interface roughness scattering of coherent and incoherent (thermalized) excitons is observed.

Physica Scripta•Jan 1, 1994•9 citations

Nonlinear Response of Localized Excitons: Effects of the Excitation-Induced Dephasing

Paola Borri, W. Langbein, D. Birkedal +2 more

The polarization dependence of the ultrafast nonlinear response of localized excitons in GaAs/AlGaAs quantum wells has been investigated by spectrally resolved, transient four-wave mixing. The role of the excitation-induced dephasing in the delay dependence of the signal is discussed in detail. In particular, we show experimentally that the excitation-induced dephasing gives rise to a photon echo in inhomogeneous systems. We develop a simple analytical model for the delay dependence of the signal, which enables us to deduce the dephasing time from the four-wave mixing decay.

physica status solidi (a)•Nov 1, 1997•8 citations

Coherent excitonic nonlinearity versus inhomogeneous broadening in single quantum wells

W. Langbein, Paola Borri, J. M. Hvam +1 more

Summary form only given.The coherent response of excitons in semiconductor nanostructures, as measured in four wave mixing (FWM) experiments, depends strongly on the inhomogeneous broadening of the exciton transition. We investigate GaAs-AlGaAs single quantum wells (SQW) of 4 nm to 25 nm well width. Two main mechanisms are found to be important. First, the excitation-induced dephasing FWM signal (EID), which leads to a strong dependence of the signal on the angle between the linear input polarizations. The presence of the EID in the mainly homogeneously broadened sample (25 nm) is shown by the beating between EID and two-photon coherence (TPC) at the exciton for negative delay and co-linear polarized excitation. It vanishes for cross-polarized excitation, thus excluding the importance of local-field effects.

Conference on Lasers and Electro-Optics•Nov 27, 2002•0 citations

Influence of Inhomogeneous Broadening on Quantum Beats

John Erland, K.‐H. Pantke, Vygantas Mizeikis +2 more

Current issues in the study of light-matter interactions are coherence and quantum interference. With ultrafast nonlinear spectroscopy such as transient four-wave mixing (TFWM) the imposed coherence on the optical excitations in e.g. GaAs multiple quantum wells has been studied. In this contribution, we study the influence of inhomogeneous broadening on quantum beats observed by spectrally resolved TFWM. In artificially grown semiconductor structures as e.g. quantum wells, inhomogeneities due to interface-disorder has, up till now, been inevitable. In the experiments, the light-hole exciton (lhx) and the heavy-hole exciton (hhx) in a 100 Å GaAs multiple quantum well are excited simultaneously with 150 fs pulses from a self mode-locked Ti:sapphire laser. The spectral profile is shown in the inset of Fig. 1.

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

Separation of inhomogeneous and homogeneous broadening manifestations in InGaAs/GaAs quantum wells by time-resolved four-wave mixing

I. A. Solovev, Yury V. Kapitonov, Boris V. Stroganov +3 more

Coherent dynamics of excitons in single InGaAs/GaAs quantum well was investigated experimentally. In order to carry out this study a three-pulse setup capable of measuring time-resolved four-wave mixing was build. Measured signal consists of two distinguishable components of similar amplitude corresponding to the fast decaying free polarization decay and the long-lived primary photon echo, which proves comparability of homogenous and inhomogeneous broadenings of the exciton resonance.

Journal of Physics Conference Series•Dec 1, 2018•3 citations

Spectral signatures of excitonic four-wave mixing signals in GaAs multiple quantum wells

John Erland, D. Birkedal, Vadim G. Lyssenko +1 more

We investigate the spectral properties of the excitonic nonlinear response in a GaAs quantum-well sample containing wells of different thicknesses. We observe both the heavy-hole biexciton and the light-hole biexciton in the transient four-wave mixing spectrum and estimate their binding energy dependence on well width. For moderate excitation densities the signal for negative delay at the heavy-hole exciton and biexciton resonances is due to two-photon transitions to the biexciton states through the exciton states. The temporal behavior of the transient four-wave mixing signal from the heavy-hole exciton resonance is strongly dependent on the spectral position of the laser. We show that this effect is due to interference phenomena and to excitation-induced dephasing.

Journal of the Optical Society of America B•May 1, 1996•13 citations
The interface roughness on a nanometer scale plays a decisive role in dephasing of excitons in GaAs multiple quantum wells. The excitonic four-wave mixing signal shows a free polarization decay and a corresponding homogeneously broadened line from areas with interface roughness on a scale larger than the exciton diameter. A photon echo and a corresponding inhomogeneously broadened line are observed from areas of interface roughness on a scale less than the exciton diameter. In the present study we observe both mechanisms simultaneously, and are able to clearly distinguish between the two mechanisms by spectrally resolving the transient four-wave-mixing signal.
By degenerate four-wave mixing experiments in a two-beam geometry, we have investigated the initial coherence and dephasing of quasi two-dimensional excitions and biexcitons in GaAs multiple quantum wells. The dephasing has contributions from phonon scattering, interface-roughness scattering and exciton-exciton scattering. Inhomogeneous broadening and generation of coherent wavepackets play a significant role in the coherent exciton dynamics. The incoherent exciton dynamics, diffusion and recombination, is studied by three-beam transient grating experiments. A significant difference in the interface roughness scattering of coherent and incoherent (thermalized) excitons is observed.
The polarization dependence of the ultrafast nonlinear response of localized excitons in GaAs/AlGaAs quantum wells has been investigated by spectrally resolved, transient four-wave mixing. The role of the excitation-induced dephasing in the delay dependence of the signal is discussed in detail. In particular, we show experimentally that the excitation-induced dephasing gives rise to a photon echo in inhomogeneous systems. We develop a simple analytical model for the delay dependence of the signal, which enables us to deduce the dephasing time from the four-wave mixing decay.
Summary form only given.The coherent response of excitons in semiconductor nanostructures, as measured in four wave mixing (FWM) experiments, depends strongly on the inhomogeneous broadening of the exciton transition. We investigate GaAs-AlGaAs single quantum wells (SQW) of 4 nm to 25 nm well width. Two main mechanisms are found to be important. First, the excitation-induced dephasing FWM signal (EID), which leads to a strong dependence of the signal on the angle between the linear input polarizations. The presence of the EID in the mainly homogeneously broadened sample (25 nm) is shown by the beating between EID and two-photon coherence (TPC) at the exciton for negative delay and co-linear polarized excitation. It vanishes for cross-polarized excitation, thus excluding the importance of local-field effects.
Current issues in the study of light-matter interactions are coherence and quantum interference. With ultrafast nonlinear spectroscopy such as transient four-wave mixing (TFWM) the imposed coherence on the optical excitations in e.g. GaAs multiple quantum wells has been studied. In this contribution, we study the influence of inhomogeneous broadening on quantum beats observed by spectrally resolved TFWM. In artificially grown semiconductor structures as e.g. quantum wells, inhomogeneities due to interface-disorder has, up till now, been inevitable. In the experiments, the light-hole exciton (lhx) and the heavy-hole exciton (hhx) in a 100 Å GaAs multiple quantum well are excited simultaneously with 150 fs pulses from a self mode-locked Ti:sapphire laser. The spectral profile is shown in the inset of Fig. 1.
We investigate the spectral properties of the excitonic nonlinear response in a GaAs quantum-well sample containing wells of different thicknesses. We observe both the heavy-hole biexciton and the light-hole biexciton in the transient four-wave mixing spectrum and estimate their binding energy dependence on well width. For moderate excitation densities the signal for negative delay at the heavy-hole exciton and biexciton resonances is due to two-photon transitions to the biexciton states through the exciton states. The temporal behavior of the transient four-wave mixing signal from the heavy-hole exciton resonance is strongly dependent on the spectral position of the laser. We show that this effect is due to interference phenomena and to excitation-induced dephasing.