© 2026 Aqora Quantum S.A.S.

Terms Privacy Legal Notice

Physical review. B, Condensed matter

Instantaneous contribution in time-resolved four-wave mixing from GaAs quantum wells near zero time delay

D. S. KIM, Jagdeep Shah, Theo C. Damen, W. Schäfer, Loren N. Pfeiffer, Klaus Köhler

Published Nov 15, 1994• 8 citations

Abstract

We show the existence of an instantaneous contribution to the time-resolved four-wave mixing (FWM) from GaAs quantum wells near zero time delay (T=0), which is very sensitive to the excitation density and detuning. In spectrally resolved (SR) FWM, this instantaneous contribution corresponds to a broad background, which is stronger in samples with larger inhomogeneous broadening. This spectral background extends well below the heavy-hole exciton, implying that diffraction of laser spectral components with no corresponding density of states occurs near zero delay. Theoretical calculations show that the origin of this instantaneous signal is the free induction decay of off-resonance laser fields, which is dramatically enhanced by the strong pulse overlap and the resulting population grating near T=0. Away from T=0, the delayed, interaction-induced signal dominates. Three-beam SR-FWM also shows the existence of a similar contribution when the first two beams overlap and the third beam is diffracted off the population grating.

DOI: 10.1103/physrevb.50.15086

Related papers

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

Femtosecond coherent fields induced by many-particle correlations in transient four-wave mixing

W. Schäfer, D. S. Kim, Jagdeep Shah +5 more

We present a unified microscopic approach to four-wave mixing (FWM) in semiconductors on an ultrashort time scale. The theory is valid for resonant excitation in the vicinity of the excitonic resonance and at low densities. The most important many-particle effects, i.e., static and dynamical exciton-exciton interaction as well as biexcitonic effects are incorporated. The internal fields resulting from these interaction processes give rise to pronounced many-particle effects in FWM signals. Our results explain the dependence of FWM signals on the polarization geometry, especially if biexcitons contribute. Time-resolved (TR) FWM experiments show that the diffraction of the interaction induced fields dominate the FWM signals completely. This dominance of the interaction induced field at low temperatures is true regardless of density, detuning, or polarization geometry. While spectrally resolved FWM (-FWM) shows biexcitonic or bound excitonic contributions under various experimental conditions, TR-FWM is always completely delayed, peaking roughly at the dephasing time after both beams passed through. \textcopyright{} 1996 The American Physical Society.

Physical review. B, Condensed matter•Jun 15, 1996•105 citations

Exciton coherence in GaAs quantum wells probed by four wave mixing measurements at high excitation intensities

Bipul Pal, Arvind S. Vengurlekar

We perform two beam time integrated (TI) degenerate four wave mixing (DFWM) measurements on 8~nm GaAs quantum wells (QW). Pulses from a Ti-Sapphire laser resonantly excite only 1s heavy hole excitons. The power density of the leading pulse (I1) is increased, keeping that of the delayed pulse fixed and relatively small. We measure the TI-DFWM signal at different delays as well as the DFWM spectra at a fixed delay, as I1 is increased. We find that the dephasing rate, after an initial increase with I1, becomes independent of I1 for large I1. The spectrally integrated DFWM signal, which probes the coherent polarization of the resonantly excited QWs, initially increases with I1, reaches a peak and then decreases as 1/(root)I1 at large I1. The results are compared with theoretical models of exciton coherence.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Jun 13, 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

Continuum contribution to excitonic four-wave mixing due to interaction-induced nonlinearities

D. Birkedal, Vadim G. Lyssenko, J. M. Hvam +1 more

We present an experimental and theoretical investigation of ultrafast transient four-wave mixing of GaAs/ ${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As quantum wells for coherent excitation of exciton and continuum states. The signal appears at the exciton resonance and is shown to consist of two contributions: an intense spectrally narrow part only present for short time delays and a weak exponentially decaying part reflecting the intrinsic coherence properties of the exciton states. The intense part of the signal is due to the excitation of the continuum states mediated by interaction-induced nonlinearities. \textcopyright{} 1996 The American Physical Society.

Physical review. B, Condensed matter•Nov 15, 1996•38 citations

Giant excitonic resonance in time-resolved four-wave mixing in quantum wells

Dai‐Sik Kim, Jagdeep Shah, J. E. Cunningham +4 more

We report a strong (300:1) excitonic resonance in time-resolved (100 fs) four-wave mixing in GaAs quantum wells as a function of the incident photon energy and show that it results from the large difference in the dephasing rates of excitons and free carriers. We conclude that excitons dominate even when they make up only a small fraction of the excited states. These results, in conjuction with new results in exciton-phonon scattering, provide new insights into previous studies performed with spectrally broad ultrashort pulses.

Physical Review Letters•Feb 17, 1992•124 citations

We show the existence of an instantaneous contribution to the time-resolved four-wave mixing (FWM) from GaAs quantum wells near zero time delay (T=0), which is very sensitive to the excitation density and detuning. In spectrally resolved (SR) FWM, this instantaneous contribution corresponds to a broad background, which is stronger in samples with larger inhomogeneous broadening. This spectral background extends well below the heavy-hole exciton, implying that diffraction of laser spectral components with no corresponding density of states occurs near zero delay. Theoretical calculations show that the origin of this instantaneous signal is the free induction decay of off-resonance laser fields, which is dramatically enhanced by the strong pulse overlap and the resulting population grating near T=0. Away from T=0, the delayed, interaction-induced signal dominates. Three-beam SR-FWM also shows the existence of a similar contribution when the first two beams overlap and the third beam is diffracted off the population grating.

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.

We present a unified microscopic approach to four-wave mixing (FWM) in semiconductors on an ultrashort time scale. The theory is valid for resonant excitation in the vicinity of the excitonic resonance and at low densities. The most important many-particle effects, i.e., static and dynamical exciton-exciton interaction as well as biexcitonic effects are incorporated. The internal fields resulting from these interaction processes give rise to pronounced many-particle effects in FWM signals. Our results explain the dependence of FWM signals on the polarization geometry, especially if biexcitons contribute. Time-resolved (TR) FWM experiments show that the diffraction of the interaction induced fields dominate the FWM signals completely. This dominance of the interaction induced field at low temperatures is true regardless of density, detuning, or polarization geometry. While spectrally resolved FWM (-FWM) shows biexcitonic or bound excitonic contributions under various experimental conditions, TR-FWM is always completely delayed, peaking roughly at the dephasing time after both beams passed through. \textcopyright{} 1996 The American Physical Society.

We perform two beam time integrated (TI) degenerate four wave mixing (DFWM) measurements on 8~nm GaAs quantum wells (QW). Pulses from a Ti-Sapphire laser resonantly excite only 1s heavy hole excitons. The power density of the leading pulse (I1) is increased, keeping that of the delayed pulse fixed and relatively small. We measure the TI-DFWM signal at different delays as well as the DFWM spectra at a fixed delay, as I1 is increased. We find that the dephasing rate, after an initial increase with I1, becomes independent of I1 for large I1. The spectrally integrated DFWM signal, which probes the coherent polarization of the resonantly excited QWs, initially increases with I1, reaches a peak and then decreases as 1/(root)I1 at large I1. The results are compared with theoretical models of exciton coherence.

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 present an experimental and theoretical investigation of ultrafast transient four-wave mixing of GaAs/

{\mathrm{Al}}_{\mathit{x}}

${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As quantum wells for coherent excitation of exciton and continuum states. The signal appears at the exciton resonance and is shown to consist of two contributions: an intense spectrally narrow part only present for short time delays and a weak exponentially decaying part reflecting the intrinsic coherence properties of the exciton states. The intense part of the signal is due to the excitation of the continuum states mediated by interaction-induced nonlinearities. \textcopyright{} 1996 The American Physical Society.

We report a strong (300:1) excitonic resonance in time-resolved (100 fs) four-wave mixing in GaAs quantum wells as a function of the incident photon energy and show that it results from the large difference in the dephasing rates of excitons and free carriers. We conclude that excitons dominate even when they make up only a small fraction of the excited states. These results, in conjuction with new results in exciton-phonon scattering, provide new insights into previous studies performed with spectrally broad ultrashort pulses.