2D optical photon echo spectroscopy of a self‐assembled quantum dot

Abstract

Simulations of two dimensional coherent photon echo (2D-PE) spectra of self-assembled InAs/GaAs quantum dots (QD) in different charged states are presented revealing the coupling between the individual mono-exciton X q transitions and contributions of bi-excitons X X q . The information about the X X q states is crucial for various application scenarios of QDs, like e.g. highly efficient solar cells. The simulations rely on a microscopic description of the electronic structure by high-level atomistic many-body pseudopotential calculations. It is shown that asymmetric diagonal peak shapes and double cross-peaks are the result of X X q state contributions to the PE signal by analyzing the contributions of the individual pathways excited state emission, ground state bleach and excited state absorption. The results show that from the detuned X q and X X q contributions the bi-exciton binding energies of the X X q manifold are revealed in 2D-PE signals.

Spectral Filtering as a Tool for Two-Dimensional Spectroscopy: A Theoretical Model

“…6 These coherences have been utilized for the investigation of energy transfer in photosynthetic light harvesting complexes, 7-17 as well as the determination of the excitonic structure of quantum dots. [18][19][20][21] Organic dye molecules and macrocycles such as cyanines, [22][23][24] and porphyrins, 25,26 as well as chromophores such as chlorophyll, [27][28][29] have been extensively studied to explore the origins of these coherences in biological complexes. Homodimers and larger aggregates are used as analogues of the multichromophoric structures.…”

“…The proliferation of two-dimensional optical spectroscopy (2DOS) has revolutionized research into the structure and dynamics of chemical systems. − The detection of coherent quantum superpositions can identify electronic couplings and the existence of excitonic states as well as vibronic couplings and the motions of nuclear wavepackets on a potential energy surface. , The study of such coherences requires the use of ultrafast spectroscopic techniques, where 2DOS provides a means of differentiating individual coherence pathways . These coherences have been utilized for the investigation of energy transfer in photosynthetic light harvesting complexes − as well as the determination of the excitonic structure of quantum dots. − Organic dye molecules and macrocycles such as cyanines − and porphyrins, , as well as chromophores such as chlorophyll, − have been extensively studied to explore the origins of these coherences in biological complexes. Homodimers and larger aggregates are used as analogues of the multichromophoric structures. − 2DOS has also found application to studies of photochemistry and reaction dynamics. − …”

Coherent coupling of individual quantum dots measured with phase-referenced two-dimensional spectroscopy: Photon echo versus double quantum coherence

“…Here, we perform FWM spectroscopy of individual InAs QDs embedded in a low-Q semiconductor microcavity [2,22,25]. We point out two major advancements: Firstly, we demonstrate 2D FWM constructed from twophoton coherences -known as double quantum 2D FWM [27][28][29] -driven on individual transitions, specifically QD exciton-biexciton systems (GXB) [30]. Secondly, we introduce referencing of the FWM phase, offering convienient alternative for its active-stabilization, which is widely believed to be required in 2D spectroscopy.…”

Efficient numerical method for calculating Coulomb coupling elements and its application to two-dimensional spectroscopy

“…26 Eqs. (26) and (27) show, that the signal of the DQCS is determined by the laser pulses with the frequency Ω 1 for…”

“…The position of the signal in the DQCS indicates the energy of the involved transitions between the ground and the exciton states on the Ω 1 -axis and between the ground and the biexciton states on the Ω 2 -axis. To balance strong signatures as well as weak signatures in the DQCS, a nonlinear scale is chosen: S nl = arsinh(|S(T 3 , Ω 2 , Ω 1 )|/N ) including a normalization constant N 27. …”