Nano Lett. 18, 7969–7976 (2018)

Quantum dots (QDs) are promising light sources for on-chip quantum photonic circuits because they can generate near-ideal single photons. However, precise control over the spatial position and emission wavelength of QDs is still a challenge. To address these issues, Ali Elshaari and co-workers from Switzerland, The Netherlands, China and Canada have now developed a waveguide-coupled nanowire single-photon source. To tune the emission wavelength by strain, a Si3N4/SiO2 (core/clad) waveguide was fabricated on a 300-μm-thick piezoelectric crystal composed of lead magnesium niobate–lead titanate (PMN–PT) that is connected to Cr/Au electrodes. Preselected InAsP/InP nanowire QDs were then transferred onto the Si3N4 layer using a nanomanipulator with a positional accuracy of within 500 nm. The thicknesses of the Si3N4 and SiO2 layers were 230 nm and 2 μm, respectively. The QDs were cooled at 5.8 K and excited non-resonantly at 795 nm. When the piezovoltage was tuned from –600 to +600 V, the wavelength of the emitted single photons was linearly tuned around 885 nm by up to 0.39 nm. The tuning range was increased to 1.6 nm by depositing additional layers of Si3N4 and SiO2 onto the nanowire.