Photon echo transients from an inhomogeneous ensemble of semiconductor quantum dots

Abstract

An ensemble of quantum dot excitons may be used for coherent information manipulation. Due to the ensemble inhomogeneity any optical information retrieval occurs in form of a photon echo.We show that the inhomogeneity can lead to a significant deviation from the conventional echo timing sequence. Variation of the area of the initial rotation pulse, which generates excitons in a dot sub-ensemble only, reveals this complex picture of photon echo formation. We observe a retarded echo for π/2 pulses, while for 3π/2 the echo is advanced in time as evidenced through monitoring the Rabi oscillations in the time-resolved photon echo amplitude from (In,Ga)As/GaAs self-assembled quantum dot structures and confirmed by detailed calculations.

Studies of photon echo from exciton ensemble in (In,Ga)As quantum dots

“…2. Theoretical analysis of the obtained dependencies for excitons (1)(2)(3)(4)(5) and of the similar theoretical dependencies for trions (6-10) described in Ref. [1] allows us to propose the polarization protocols of optical excitation to separate experimentally the contributions of the exciton and the trion PE signals.…”

Photon echoes from (In,Ga)As quantum dots embedded in a Tamm-plasmon microcavity

“…where 2 = 2|E 2 d|/h is the Rabi frequency which is determined by the electric field amplitude of the second pulse E 2 1 Strong inhomogeneous broadening of optical transitions can lead to a significant modification of the photon echo transients when the energy of the first pulse is scanned [21]. and the dipole matrix element of the two-level system d. In our case τ d is fixed while E 2 ∝ √ P 2 is varied.…”

“…TFWM and two-dimensional Fourier spectroscopy were used to investigate the coherent optical response of exciton polaritons in QW-and QDbased microcavities with high quality factors (strong coupling regime) [2,18,19]. QDs were also implemented in low quality DBR-based cavities in order to increase the strength of the TFWM signal and to study the corresponding coherent optical phenomena [20][21][22]. However, studies of the nonlinear optical response under resonant excitation in TP resonators is lacking.…”

“…In order to prevent tunneling of photoexcited carriers into the metal layer, a 10 nm Al 0.2 Ga 0.8 As barrier was introduced between the QDs and the surface (20 nm below the surface). We also studied structures with a single layer of (In,Ga)As QDs which is embedded in a GaAs λ microcavity of similar quality factor formed by two DBR mirrors [21].…”

“…From these parameters we expect that the TFWM signal is determined by photon echoes due to the inhomogeneous broadening of the optical transitions in the QD ensemble. In the case of the TP microcavity, the broadening is given by the spectral width of the photonic mode [21].…”