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 Letters

Femtosecond dephasing in CdSx Se1−x mixed crystals: The role of localized biexcitons

J.‐Y. Bigot, A. Daunois, Jean Oberlé, J.‐C. Merle

Published Sep 20, 1993• 35 citations
Publisher

Abstract

The dephasing of excitonic localized states is investigated in ${\mathrm{CdS}}_{\mathit{x}}$${\mathrm{Se}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$ mixed crystals at 2 K with low intensity femtosecond optical pulses. We observe a fast relaxation process which is first reported here. It is shown to be related to the creation of localized biexcitons via the exciton-biexciton transitions which act as an additional dephasing mechanism with a time constant ${\mathit{T}}_{2}^{\mathrm{ex}\mathrm{\ensuremath{-}}\mathrm{bi}}$ of 700 fs. The coherence between excitonic and biexcitonic states, which manifests by 800 fs period beats, is studied in detail. A simple model is presented which describes both the fast initial decay and the beating behavior.

DOI
10.1103/physrevlett.71.1820

Related papers

Femtosecond four-wave mixing spectroscopy on CdS crystal at room temperature

Иванин Константин Валерьевич, Andrey V. Leontyev, Vladimir S. Lobkov +4 more

The results of the femtosecond four-wave mixing measurements performed on the CdS crystal at room temperature are reported. The dephasing time T d = 180 fs was obtained. The anti-Stokes shift of the primary photon echo spectrum with respect to the excitation spectrum was observed. The some peculiarities of the coherent responses decay curves indicate that this optical dephasing is due to the exciton-exciton interaction. The stimulated photon echo decay curves appear to have a fast decay component (the time constant of approximately 4.5 ps) in case the energy of exciting pulses exceeds the threshold value of 0.4 μJ.

Laser Physics Letters•Jun 2, 2009•10 citations

Фемтосекундная спектроскопия четырехволнового смешения в кристалле CdS

Иванин Константин Валерьевич, Леонтьев Андрей Владимирович, Лобков Владимир Сергеевич +3 more

Femtosecond four-wave mixing coherent specstroscopy in CdS crystal on 790 nm at room temperature is analyzed. It is stated that the optical dephasing time is equal to 180 fs. Some specific features of the coherent responses' decay curves indicate that this optical dephasing is due to exciton-exciton interaction. The stimulated photon echo decay curves appear to have a fast decay component (the time constant of approximately 4.5 ps), in case when the energy of exciting pulses exceeds the threshold value of 0.4 μJ.

Ученые записки Казанского университета. Серия Физико-математические науки•Jan 1, 2009•0 citations

Optical dephasing in semiconductor mixed crystals

U. Siegner, D. Weber, Ernst Otto Göbel +9 more

The influence of disorder and localization on optical dephasing of excitons in the semiconductor mixed crystals ${\mathrm{CdS}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Se}}_{\mathit{x}}$ and ${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As has been investigated by means of time-resolved four-wave mixing and photon echo experiments. A dephasing time of several hundreds of picoseconds is found for resonantly excited localized excitons in ${\mathrm{CdS}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Se}}_{\mathit{x}}$ while the dephasing time in ${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As amounts to only a few picoseconds. In ${\mathrm{CdS}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Se}}_{\mathit{x}}$ dephasing results mainly from hopping processes, i.e., exciton-phonon interaction. The contribution of disorder is negligible in terms of phase relaxation in ${\mathrm{CdS}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Se}}_{\mathit{x}}$. In contrast, in ${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As elastic disorder scattering yields an essential contribution to the dephasing rate. We present a theoretical model, which treats dephasing of optical excitations in a disordered semiconductor, including the influence of disorder as well as exciton-phonon interaction. On the base of this model, the experimentally observed differences in the dephasing behavior of excitons in ${\mathrm{CdS}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Se}}_{\mathit{x}}$ and ${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As are related to the microscopic structure of the disorder potential and the mechanism of exciton localization.

Physical review. B, Condensed matter•Aug 15, 1992•66 citations

Optical nonlinearities and phase coherence in CdSe studied by transient four-wave mixing

Claus Dörnfeld, J. M. Hvam

A picosecond time-resolved four-wave mixing technique is used to study the dephasing of nonlinear optical resonances in CdSe. At low temperature strong coherent, nonlinear signals at the free exciton resonance, at the biexciton resonance, and at the exciton-biexciton transition are observed. The observed correlation traces, i.e. the diffracted intensity versus the delay between the interfering light pulses, yield information on the dephasing process. Dephasing times for excitons as long as 40 ps, decreasing with increasing excitation density and temperature, are observed. A two-level model is applied to describe theoretically the dynamical behavior of the resonances, and to extract their homogeneous broadening, as well as their inhomogeneous broadening.

IEEE Journal of Quantum Electronics•May 1, 1989•86 citations

Role of incoherent excitons and biexcitons in the nonlinear coherent optical response in ZnSe MQWs

Kōichiro Tanaka, 真一郎 畑岡, Ryohei Wakai +1 more

Femtosecond spectrally resolved four-wave mixing technique was applied to study many-body interactions of excitons. We observed decrease of the effective transition dipole moment and excitation-induced dephasing both in exciton and biexciton resonance.

Nonlinear Optics•Jan 1, 2000•0 citations

Role of incoherent excitons and biexcitons in the nonlinear coherent optical response in ZnSe MQWs

K. Tanaka, S. Hataoka, Ryohei Wakai +1 more

Femtosecond spectrally resolved four-wave mixing technique was applied to study many-body interactions of excitons. We observed decrease of the effective transition dipole moment and excitation-induced dephasing both in exciton and biexciton resonance.

Nonlinear Optics: Materials, Fundamentals, and Applications. Technical Digest. Postconference Edition. TOPS Vol.46 (IEEE Cat. No.00CH37174)•Nov 7, 2002•0 citations
The dephasing of excitonic localized states is investigated in {\mathrm{CdS}}_{\mathit{x}}$${\mathrm{Se}}_{1\mathrm{\ensuremath{-}}\mathit{x}} mixed crystals at 2 K with low intensity femtosecond optical pulses. We observe a fast relaxation process which is first reported here. It is shown to be related to the creation of localized biexcitons via the exciton-biexciton transitions which act as an additional dephasing mechanism with a time constant T2ex\ensuremath−bi{\mathit{T}}_{2}^{\mathrm{ex}\mathrm{\ensuremath{-}}\mathrm{bi}}T2ex\ensuremath−bi​ of 700 fs. The coherence between excitonic and biexcitonic states, which manifests by 800 fs period beats, is studied in detail. A simple model is presented which describes both the fast initial decay and the beating behavior.
The results of the femtosecond four-wave mixing measurements performed on the CdS crystal at room temperature are reported. The dephasing time T d = 180 fs was obtained. The anti-Stokes shift of the primary photon echo spectrum with respect to the excitation spectrum was observed. The some peculiarities of the coherent responses decay curves indicate that this optical dephasing is due to the exciton-exciton interaction. The stimulated photon echo decay curves appear to have a fast decay component (the time constant of approximately 4.5 ps) in case the energy of exciting pulses exceeds the threshold value of 0.4 μJ.
Femtosecond four-wave mixing coherent specstroscopy in CdS crystal on 790 nm at room temperature is analyzed. It is stated that the optical dephasing time is equal to 180 fs. Some specific features of the coherent responses' decay curves indicate that this optical dephasing is due to exciton-exciton interaction. The stimulated photon echo decay curves appear to have a fast decay component (the time constant of approximately 4.5 ps), in case when the energy of exciting pulses exceeds the threshold value of 0.4 μJ.
The influence of disorder and localization on optical dephasing of excitons in the semiconductor mixed crystals ${\mathrm{CdS}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$Sex{\mathrm{Se}}_{\mathit{x}}Sex​ and Alx{\mathrm{Al}}_{\mathit{x}}Alx​${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As has been investigated by means of time-resolved four-wave mixing and photon echo experiments. A dephasing time of several hundreds of picoseconds is found for resonantly excited localized excitons in ${\mathrm{CdS}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$Sex{\mathrm{Se}}_{\mathit{x}}Sex​ while the dephasing time in Alx{\mathrm{Al}}_{\mathit{x}}Alx​${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As amounts to only a few picoseconds. In ${\mathrm{CdS}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$Sex{\mathrm{Se}}_{\mathit{x}}Sex​ dephasing results mainly from hopping processes, i.e., exciton-phonon interaction. The contribution of disorder is negligible in terms of phase relaxation in ${\mathrm{CdS}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$Sex{\mathrm{Se}}_{\mathit{x}}Sex​. In contrast, in Alx{\mathrm{Al}}_{\mathit{x}}Alx​${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As elastic disorder scattering yields an essential contribution to the dephasing rate. We present a theoretical model, which treats dephasing of optical excitations in a disordered semiconductor, including the influence of disorder as well as exciton-phonon interaction. On the base of this model, the experimentally observed differences in the dephasing behavior of excitons in ${\mathrm{CdS}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$Sex{\mathrm{Se}}_{\mathit{x}}Sex​ and Alx{\mathrm{Al}}_{\mathit{x}}Alx​${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As are related to the microscopic structure of the disorder potential and the mechanism of exciton localization.
A picosecond time-resolved four-wave mixing technique is used to study the dephasing of nonlinear optical resonances in CdSe. At low temperature strong coherent, nonlinear signals at the free exciton resonance, at the biexciton resonance, and at the exciton-biexciton transition are observed. The observed correlation traces, i.e. the diffracted intensity versus the delay between the interfering light pulses, yield information on the dephasing process. Dephasing times for excitons as long as 40 ps, decreasing with increasing excitation density and temperature, are observed. A two-level model is applied to describe theoretically the dynamical behavior of the resonances, and to extract their homogeneous broadening, as well as their inhomogeneous broadening.