biostudies-literatureUnknown11(13)Huang XEpitaxial semiconductor quantum dots (QDs) have been demonstrated as on-demand entangled photon sources through biexciton-exciton (XX-X) cascaded radiative processes. However, perfect entangled photon emitters at the specific wavelengths of 880 nm or 980 nm, that are important for heralded entanglement distribution by absorptive quantum memories, remain a significant challenge. We successfully extend the QD emission wavelength to 880 nm via capping Stranski-Krastanow grown In(Ga)As/GaAs QDs with an ultra-thin Al _<i>x</i> Ga_1-<i>x</i> As layer. After carefully investigating the mechanisms governing the vanishing of wetting-layer (WL) states and the anisotropy of QDs, we optimize the growth conditions and achieve a strong suppression of the WL emission as well as a measured minor fine structure splitting of only ∼(3.2 ± 0.25) μeV for the exciton line. We further extend this method to fabricate In(Ga)As QDs emitted at 980 nm via introducing InGaAs capping layer, and demonstrate a two-photon resonant excitation of the biexciton without any additional optical or electrical stabilized source. These QDs with high symmetry and stability represent a highly promising platform for the generation of polarization entanglement and experiments on the interaction of photons from dissimilar sources, such as rare-earth-ion-doped crystals for solid quantum memory.Nanophotonics (Berlin, Germany)3093-3100https://www.ebi.ac.uk/biostudies/studies/S-EPMC11501422biostudies-literatureSelf-assembled InAs/GaAs single quantum dots with suppressed InGaAs wetting layer states and low excitonic fine structure splitting for quantum memory.PMC11501422Yang JYu SHuang XSong CRao MYu YfalseSelf-assembled InAs/GaAs single quantum dots with suppressed InGaAs wetting layer states and low excitonic fine structure splitting for quantum memory.Epitaxial semiconductor quantum dots (QDs) have been demonstrated as on-demand entangled photon sources through biexciton-exciton (XX-X) cascaded radiative processes. However, perfect entangled photon emitters at the specific wavelengths of 880 nm or 980 nm, that are important for heralded entanglement distribution by absorptive quantum memories, remain a significant challenge. We successfully extend the QD emission wavelength to 880 nm via capping Stranski-Krastanow grown In(Ga)As/GaAs QDs with an ultra-thin Al _<i>x</i> Ga_1-<i>x</i> As layer. After carefully investigating the mechanisms governing the vanishing of wetting-layer (WL) states and the anisotropy of QDs, we optimize the growth conditions and achieve a strong suppression of the WL emission as well as a measured minor fine structure splitting of only ∼(3.2 ± 0.25) μeV for the exciton line. We further extend this method to fabricate In(Ga)As QDs emitted at 980 nm via introducing InGaAs capping layer, and demonstrate a two-photon resonant excitation of the biexciton without any additional optical or electrical stabilized source. These QDs with high symmetry and stability represent a highly promising platform for the generation of polarization entanglement and experiments on the interaction of photons from dissimilar sources, such as rare-earth-ion-doped crystals for solid quantum memory.2022-01-01T00:00:00Z2022 Jun2025-04-04T01:06:11.614Z2025-04-04T01:06:11.614ZS-EPMC115014223963466710.1515/nanoph-2022-0120