Due to their band-structure and optical properties, InAs/InP quantum dots (QDs) constitute a promising system for single-photon generation at the third telecom window of silica fibers and for applications in quantum communication networks. However, obtaining the necessary low in-plane density of emitters remains a challenge. Such structures are also still less explored than their InAs/GaAs counterparts regarding optical properties of confined carriers. Here, we report on the growth via metal-organic vapor phase epitaxy and investigation of low-density InAs/InP QD-like structures, emitting in the range of 1.2-1.7 μm, which includes the S, C, and L bands of the third optical window. We observe multiple photoluminescence (PL) peaks originating from flat QDs with the height of a few material monolayers. Temperature-dependent PL reveals a redistribution of carriers between families of QDs. Via time-resolved PL, we obtain radiative lifetimes nearly independent of emission energy in contrast to previous reports on InAs/InP QDs, which we attribute to strongly height-dependent electron-hole correlations. Additionally, we observe neutral and charged exciton emission from spatially isolated emitters. Using the eight-band k•p model and configuration-interaction method, we successfully reproduce the energies of emission lines, the dispersion of exciton lifetimes, the carrier activation energies, as well as the biexciton binding energy, which allows for a detailed and comprehensive analysis of the underlying physics.

The authors demonstrate pure triggered single‐photon emission from quantum dots (QDs) around the telecommunication C‐band window, with characteristics preserved under non‐resonant excitation at saturation, that is, the highest possible, lifetime‐limited emission rates. The direct measurement of emission dynamics reveals photoluminescence decay times in the range of (1.7–1.8) ns corresponding to maximal photon generation rates exceeding 0.5 GHz. The measurements of the second‐order correlation function exhibit, for the best case, a lack of coincidences at zero time delay—no multiple photon events are registered within the experimental accuracy. This is achieved by exploiting a new class of low‐density and in‐plane symmetric InAs/InP QDs grown by molecular beam epitaxy on a distributed Bragg reflector, perfectly suitable for non‐classical light generation for quantum optics experiments and quantum‐secured fiber‐based optical communication schemes.

In this work we demonstrate a triggered single-photon source operating at the telecom C-band with photon extraction efficiency exceeding any reported values in this range. The non-classical light emission with low probability of the multiphoton events is realized with single InAs quantum dots (QDs) grown by molecular beam epitaxy and embedded directly in an InP matrix.Low QD spatial density on the order of 5x10 8 cm -2 to ~2x10 9 cm -2 and symmetric shape of these nanostructures together with spectral range of emission makes them relevant for quantum communication applications. The engineering of extraction efficiency is realized by combining a bottom distributed Bragg reflector consisting of 25 pairs of InP/In0.53Ga0.37Al0.1As layers and cylindrical photonic confinement structures. Realization of such technologically nondemanding approach even in a non-deterministic fashion results in photon extraction efficiency of (13.3±2)% into 0.4 numerical aperture detection optics at approx. 1560 nm emission wavelength, i.e., close to the center of the telecom C-band.