Enhancement of Single‐Photon Purity and Coherence of III‐Nitride Quantum Dot with Polarization‐Controlled Quasi‐Resonant Excitation

Abstract

III‐Nitride semiconductor‐based quantum dots (QDs) play an essential role in solid‐state quantum light sources because of their potential for room‐temperature operation. However, undesired background emission from the surroundings deteriorates single‐photon purity. Moreover, spectral diffusion causes inhomogeneous broadening and limits the applications of QDs in quantum photonic technologies. To overcome these obstacles, it is demonstrated that directly pumping carriers to the excited state of the QD reduces the number of carriers generated in the vicinities. The polarization‐controlled quasi‐resonant excitation is applied to InGaN QDs embedded in GaN nanowire. To analyze the different excitation mechanisms, polarization‐resolved absorptions are investigated under the above‐barrier bandgap, below‐barrier bandgap, and quasi‐resonant excitation conditions. By employing polarization‐controlled quasi‐resonant excitation, the linewidth is reduced from 353 to 272 µeV, and the second‐order correlation value is improved from 0.470 to 0.231. Therefore, a greater single‐photon purity can be obtained at higher temperatures due to decreased linewidth and background emission.

Scalable Bright and Pure Single Photon Sources by Droplet Epitaxy on InP Nanowire Arrays

“…Nevertheless, at saturation level, a low g (2) (0) value of 0.19 can be achieved. This value can be further improved by using different excitation schematics such as above-band pulsed excitation, 39 p-shell resonance excitation, 40 and s-shell resonance excitation 41 in addition to spectral filtering using high-resolution gratings. Finite-difference time-domain (FDTD) simulation is used to investigate which NW mode is coupled to the QD emission and to study the Purcell enhancement effect of NWs of different sizes.…”

“…Nevertheless, at saturation level, a low g (2) (0) value of 0.19 can be achieved. This value can be further improved by using different excitation schematics such as above-band pulsed excitation, p-shell resonance excitation, and s-shell resonance excitation in addition to spectral filtering using high-resolution gratings.…”

Ultrafast and Bright Quantum Emitters from the Cavity-Coupled Single Perovskite Nanocrystals

“…We achieved clear antibunching behavior from the cavitycoupled single perovskite NC, but the background emission from Si 3 N 4 still causes the reduction of single-photon purity compared to the bare single perovskite NC on the silicon substrate (Figure S7). Here, we can further reduce the g (2) (0) value by some techniques such as quasi-resonant excitation, 30 resonant excitation, 31 and nanoscale focus pinspot. 32 Meanwhile, the Purcell enhancement in this work was 1.95.…”