We investigate charged and neutral exciton complexes confined in a single self-assembled InAs/InGaAlAs/InP quantum dash emitting at 1.55 μm. The emission characteristics have been probed by measuring high-spatial-resolution polarization-resolved photoluminescence and cross-correlations of photon emission statistics at T = 5 K. The photon auto-correlation histogram of the emission from both the neutral and charged exciton indicates a clear antibunching dip with as-measured g(2)(0) values of 0.18 and 0.31, respectively. It proves that these exciton complexes confined in single quantum dashes of InP-based material system can act as true single photon emitters being compatible with standard long-distance fiber communication technology.

Photoreflectance (PR) measurements have been performed on $\mathrm{In}\mathrm{As}∕{\mathrm{In}}_{0.53}{\mathrm{Ga}}_{0.23}{\mathrm{Al}}_{0.24}\mathrm{As}$ quantum dashes (QDashes) molecular-beam epitaxy grown on InP substrate. The PR features related to all relevant parts of the structure have been detected, including the ground and excited state optical transitions in QDashes. QDash ground state transition shifts from 1.5 to almost $2\mu \mathrm{m}$ with the increase in the thickness of InAs layer, corresponding to the increase in the average size of the dashes. Excited state transitions have been clearly observed at the energy of about $150\mathrm{meV}$ above the ground state transition energy.

Exciton and biexciton dynamics in a single self-assembled InAs/In_0.53Ga_0.23Al_0.24As/InP(001) quantum dash emitting near 1.55 μm has been investigated by micro-photoluminescence and time-resolved micro-photoluminescence at T = 4.2 K. The exciton and biexciton fine structure splitting of ∼60 μeV, the biexciton binding energy of ∼3.5 meV, and the characteristic exciton and biexciton decay times of 2.0 ± 0.1 ns and 1.1 ± 0.1 ns, respectively, have been determined. The measurement of the biexciton and exciton cross-correlation statistics of the photon emission confirmed the cascaded relaxation process. The exciton-to-biexciton decay time ratio and a small fine structure splitting suggest carrier localization within the investigated quantum dash.

Carrier relaxation dynamics in self-assembled InAs/Ga_0.2In_0.8As_0.4P_0.6/InP(001) quantum dashes (QDashes) has been studied by degenerated time-resolved pump-probe and non-resonant photoluminescence spectroscopy at low temperature. These experiments yielded information about the exciton ground-state recombination lifetime reaching ∼1.75 ns. Additionally, the excited-to-ground state relaxation time has been measured to increase significantly from ∼40 ps up to ∼250 ps with the QDash size. Slow down of the intra-band relaxation time is interpreted in terms of the internal dash-to-dash energy-band-structure variation. The carrier dynamics in this case is most likely governed by the acoustic-phonon-mediated scattering processes.

Photoluminescence and photoreflectance measurements have been performed to investigate molecular-beam-epitaxy-grown InAs/InGaAlAs/InP structures with different-size InAs quantum dashes. Optical features related to all relevant parts of the structure have been detected and recognized, including a line which has been attributed to the ground-state wetting layer quantum well transition. The spectral position of the latter is independent of the nominal InAs layer thickness in contrast to quantum-dash emission peak, which shifts sequentially to the red due to an increase of the islands’ size. The interpretation has been supported by energy level calculations showing that the wetting layer has to be approximately 2 ML thick and that only one state is confined in such a thin well for each kind of carriers, i.e., electrons, heavy, and light holes.

In this paper, we present time-resolved photoluminescence of self-assembled (In,Ga)As quantum dots (QDs) coupled to an InxGa1$-${}xAs quantum well (QW) through a thin GaAs barrier. The coupling strength is controlled by the well width and material composition and has a direct influence on the QD\char21{}QW system ground-state radiative lifetime, which increases from 1.1 up to 1.82 ns as the coupling strength increases. A thorough explanation is given for the reduction of the fundamental transition oscillator strength in the interacting system induced by the transformation of related eigenstates from a noncoupled to a coupled regime. The experimental observations have been fully confirmed by the results of three-dimensional band structure calculations of a coupled QD\char21{}QW system within the framework of eight-band k\ifmmode\cdot\else\textperiodcentered\fi{}p theory.