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Ultrafast phase dynamics of coherent carriers in GaAs

Xiangyang Yu, Qi Luo, Wen‐lan Li +3 more

Ultrafast phase dynamics of free-induction decay for carriers in bulk GaAs is studied with differential-phase spectroscopy. The instantaneous phase shifts of the free-induction decay with respect to the excitation pulses are extracted from simultaneously recorded laser pulse autocorrelation and free-induction decay in GaAs. Ultrafast phase dynamics during and immediately after the femtosecond pulse excitation are numerically evaluated with optical Bloch equations using pump pulse and semiconductor exciton parameters as input. Good agreement of the theory with experiment is obtained.Ultrafast phase dynamics of free-induction decay for carriers in bulk GaAs is studied with differential-phase spectroscopy. The instantaneous phase shifts of the free-induction decay with respect to the excitation pulses are extracted from simultaneously recorded laser pulse autocorrelation and free-induction decay in GaAs. Ultrafast phase dynamics during and immediately after the femtosecond pulse excitation are numerically evaluated with optical Bloch equations using pump pulse and semiconductor exciton parameters as input. Good agreement of the theory with experiment is obtained.

Applied Physics LettersDec 7, 199813 citations

Theoretical investigations in femtosecond coherence spectroscopy

Anand T. N. Kumar

Jan 1, 20000 citations

Coherent Effects in Femtosecond Spectroscopy: A Simple Picture Using the Bloch Equation

M. Joffre

Springer eBooksJan 1, 19982 citations

Femtosecond quantum dynamics of diatomic molecules in optically dense gaseous media

Sergey A. Moiseev, M. I. Noskov

A consistent quantum theory of a two-pulse pump-probe experiment in the femto-and picosecond spectroscopy of diatomic molecules is developed. The theory aims at the use of weak quantum femtosecond light pulses to excite molecular coherence. It is suggested that the experiment be realized using a double-frequency excitation scheme that is feasible for Na 2 molecules. On the basis of the theory developed, the luminescence signals are calculated at different temperatures and different optical densities of the medium for the time range from 100 fs to ~ 100 ps. The results obtained show the presence of a strong dependence of the time and frequency spectra of a luminescence signal on the optical density of the medium at temperatures from 50 to 300 K. The proposed approach makes it possible to use the quantum coherence properties of optically dense media for more detailed study of the vibronic dynamics of diatomic molecules, in particular, detection of weak optical transitions.A consistent quantum theory of a two-pulse pump-probe experiment in the femto-and picosecond spectroscopy of diatomic molecules is developed. The theory aims at the use of weak quantum femtosecond light pulses to excite molecular coherence. It is suggested that the experiment be realized using a double-frequency excitation scheme that is feasible for Na 2 molecules. On the basis of the theory developed, the luminescence signals are calculated at different temperatures and different optical densities of the medium for the time range from 100 fs to ~ 100 ps. The results obtained show the presence of a strong dependence of the time and frequency spectra of a luminescence signal on the optical density of the medium at temperatures from 50 to 300 K. The proposed approach makes it possible to use the quantum coherence properties of optically dense media for more detailed study of the vibronic dynamics of diatomic molecules, in particular, detection of weak optical transitions.

Optics and SpectroscopyJun 29, 20040 citations

Effects of non-Markovian relaxation in the femtosecond differential absorption spectra

E. Gaižauskas, Audrius Berzanskis, K.‐H. Feller

Chemical PhysicsSep 1, 19987 citations

Coherent population dynamics in rubidium atoms excited by resonant 0π pulses

Ticijana Ban, Damir Aumiler, Silvije Vdović +3 more

We investigate the time dynamics of a four-level rubidium atomic system excited by a train of $0\ensuremath{\pi}$ pulses. Resonant $0\ensuremath{\pi}$ pulse shaping is achieved by propagation of weak femtosecond pulses through rubidium vapor and characterized using frequency-resolved optical gating and within the linear dispersion theory. The excitation of the Rb atoms by $0\ensuremath{\pi}$ pulse train is studied experimentally by modified direct frequency comb spectroscopy and theoretically within the density-matrix approach. We show that accumulation of populations and coherences, as typical pulse train excitation effects, strongly depend on the strength of the resonant $0\ensuremath{\pi}$ pulse shaping. Stronger pulse shaping reduces the coherent accumulation effects, eventually leading to the disappearance of the velocity selective optical pumping observed in the frequency domain.We investigate the time dynamics of a four-level rubidium atomic system excited by a train of $0\ensuremath{\pi}$ pulses. Resonant $0\ensuremath{\pi}$ pulse shaping is achieved by propagation of weak femtosecond pulses through rubidium vapor and characterized using frequency-resolved optical gating and within the linear dispersion theory. The excitation of the Rb atoms by $0\ensuremath{\pi}$ pulse train is studied experimentally by modified direct frequency comb spectroscopy and theoretically within the density-matrix approach. We show that accumulation of populations and coherences, as typical pulse train excitation effects, strongly depend on the strength of the resonant $0\ensuremath{\pi}$ pulse shaping. Stronger pulse shaping reduces the coherent accumulation effects, eventually leading to the disappearance of the velocity selective optical pumping observed in the frequency domain.

Physical Review AAug 28, 20099 citations

Dynamical theory of spectroscopy with femtosecond pulse excitation (I)

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