Biexcitonic effects in the coherent control of the excitonic polarization detected in six-wave-mixing signals

Physica Status Solidi (b)

Gutowski

et al. 2006

PACS 42.65. Ky, 78.67.De In experiments and simulations based on a microscopic theory the optical coherent control of excitonbiexciton beats in coherent four-wave-mixing signals from a semiconductor quantum well is demonstrated. It is found that a reduction of the beat amplitude for one four-wave-mixing direction may at the same time coincide with a large beat amplitude for the other direction. The results can be understood by considering that at least two-photon processes are required to coherently excite biexcitonic transitions which are responsible for the occurrence of the beat structure in the four-wave-mixing signals.

Section: Experiments and Microscopic Theorymentioning

confidence: 99%

Coherent control of exciton–biexciton beats: direction selectivity of four‐wave‐mixing signals in experiment and microscopic theory

Physica Status Solidi (b)

Gutowski

et al. 2006

“…Compared to the pulse-transmission experiments in a four-wave-mixing arrangement an additional third pulse from a different direction 2 k is now applied to the sample. The resulting diffracted signal in direction 2 1 2k k -is analyzed spectrally resolved (details concerning the signal in other FWM direction 1 2 2k k -can be found in [9,16]). The excitonic transitions which are involved in the generation of the wave-mixing signal can be visualized by considering a simplified phenomenological few-level energy diagram [10,11,16] for the important model case of an exciton-biexciton system.…”

Section: Coherent Control Of Linear Excitonic Polarizationmentioning

confidence: 99%

“…The resulting diffracted signal in direction 2 1 2k k -is analyzed spectrally resolved (details concerning the signal in other FWM direction 1 2 2k k -can be found in [9,16]). The excitonic transitions which are involved in the generation of the wave-mixing signal can be visualized by considering a simplified phenomenological few-level energy diagram [10,11,16] for the important model case of an exciton-biexciton system. Starting from the unexcited ground state of the semiconductor an excitonic polarization can be created by the absorption of a photon at the energy position of the exciton transition XT.…”

Section: Coherent Control Of Linear Excitonic Polarizationmentioning

confidence: 99%

“…The microscopic simulations of the coherent control of the XT and EBT were performed by use of a density-matrix formalism based on the dynamics-controlled truncation scheme (DCT) in the so-called coherent limit [16]. On this level of the theory which is exact within third order of the electric field the dynamics of the coherent polarization is described by the time evolution of the single-pair transition amplitude Y and the correlated two-pair transition amplitude B .…”

Section: Coherent Control Of Linear Excitonic Polarizationmentioning

confidence: 99%

See 1 more Smart Citation

Coherent control of excitonic excitations in II–VI quantum wells

Breunig

Physica Status Solidi (b)

et al. 2006

We present results of experimental work in which the coherent-control technique has been applied to study the coherent manipulation of excitonic polarization in ZnSe quantum-well samples. We will introduce the linear control of excitonic polarization in pulse-transmission experiments and afterwards focus on the question if and how the optical transition from the excitonic states to the bound-biexciton state can be subject to a directed coherent control. The experimental results will be compared to simulations based on a microscopic theory and will also be explained on the base of a phenomenological few-level model. The overall suitability of coherent control for the investigation of exciton systems in low-dimensional wide-gap materials will be discussed.

“…The control can be achieved by generating a collinear pair of laser pulses with a relative phase being tuneable with a resolution of just a fraction of the excitation wavelength [4][5][6]. This method offers the possibility to switch continuously between destructive and constructive interference for different excitations in the sample [7]. Thus, optical coherent control provides an outstanding technique to separate between certain spectral contributions in the signal by selectively exciting only one or just a few resonances in the sample.…”

mentioning

confidence: 98%

Simultaneous optical coherent control of excitonic and biexcitonic polarization in a ZnSe quantum well

Breunig

et al. 2003

phys. stat. sol. (c)

The optical coherent-control technique is used to study biexcitonic effects in the four-wave-mixing signal of a ZnSe single quantum well. The signal is analyzed in both directions 2k 1 À k 2 and 2k 2 À k 1 which are not equivalent if a pulse pair is applied from direction k 1 to achieve coherent control of the induced polarization. It is shown that the coherent control enables a selective enhancement or suppression of the contribution at the exciton and biexciton resonance to the signal, respectively, but only for certain sequences of the excitation pulses. Further, the suppression of exciton-biexciton beats in the signal as a function of t del by a selective destruction of the biexciton polarization is demonstrated.1 Introduction Optical coherent-control techniques have been widely used in the last few years since they offer the possibility to manipulate quantum-mechanical excitations with regard to both their amplitudes and relative phases [1][2][3]. The control can be achieved by generating a collinear pair of laser pulses with a relative phase being tuneable with a resolution of just a fraction of the excitation wavelength [4][5][6]. This method offers the possibility to switch continuously between destructive and constructive interference for different excitations in the sample [7]. Thus, optical coherent control provides an outstanding technique to separate between certain spectral contributions in the signal by selectively exciting only one or just a few resonances in the sample. Clearly, this argument holds for all systems containing resonances which are not coupled to each other. In the case of exciton and biexciton polarization, however, one has to deal with two resonances which are strongly coupled since a bound biexciton is composed of two excitons with opposite spins. Because of this it is not a priori clear whether the excitonic and biexcitonic contributions in a four-wave-mixing signal can be separated by applying an optical coherent-control technique. Recently, we have shown the separate coherent control of exciton and biexciton four-wave-mixing polarization by observing a phase shift between the signals at the two resonances corresponding to their energenic separation [8]. Here, we extend this work to a more general case where different sequences of the excitation pulses are used and the resulting four-wave-mixing signals are studied spectrally resolved in both directions 2k 1 À k 2 and 2k 2 À k 1 as a function of the delay time t del .