Effect of Dielectric Medium Anisotropy on the Polarization Degree of Emission from a Single Quantum Dash

Excitonic fine structure and binding energies of excitonic complexes in single InAs quantum dashes

“…2,12,13,47 Although it is difficult to precisely determine the length scaling according to a scanning electron microscope (SEM) image of uncapped QDash layers (Figure 1(b)), the nominal elongation of more than 50 nm is observed. Due to the small lattice mismatch of ~3-4 %, 48 the atom's surface diffusion coefficient anisotropy is more pronounced and then the epitaxially formed nanostructures are significantly elongated in one of the distinguished crystallographic in-plane directions (preferentially along [1][2][3][4][5][6][7][8][9][10]. 49,25 For single dash spectroscopy we used a microphotoluminescence setup equipped with a one-meter focal length monochromator, an InGaAs detector array, and a long working distance microscope objective with a numerical aperture of 0.4 to focus the excitation beam and collect the emission.…”

“…by applying electric field to low-strained InAs/InGaAs quantum dots emitting around 1260 nm, 6 or by magnetic field applied to InAs/GaAs quantum dots emitting below 900 nm, 7 a reduction of FSS has been obtained. Moreover, QDash exciton bright states exhibit a significant polarization anisotropy of emission, [8][9][10] which together with further enhancement by a simple post-growth patterning of dielectric medium can offer an efficient source of linearly polarized single photons, 8,10,11 which seems to also be quite a unique and application-relevant property of the dashes. All of these overlap with the 2 nd or 3 rd telecommunication data transmission windows [12][13][14] and thus allow considering the QDashes for realization of selected issues in quantum information processing [15][16][17] and nanophotonics.…”

“…Therefore, the hole states should in principle be more susceptible to quantum dash anisotropy resulting from highly-elongated geometry. This anisotropy is particularly strong for smaller QDashes, where hole states are affected by strong lateral confinement in the [110] direction and weak confinement in the [1][2][3][4][5][6][7][8][9][10] direction. The increased hole-hole repulsion has further a pronounced effect on the excitonic spectra.…”