Abstract
We report on single photon emitters for the green-yellow spectral range, which comprise a CdSe/ZnSe quantum dot placed inside a semiconductor tapered nanocolumn acting as a multimode nanoantenna. Despite the presence of many optical modes inside, such a nanoantenna is able to collect the quantum dot radiation and ensure its effective output. We demonstrate periodic arrays of such emitters, which are fabricated by focused ion beam etching from a II-VI/III-V heterostructure grown using molecular beam epitaxy. With non-resonant optical pumping, the average count rate of emitted single photons exceeds 5 MHz with the second-order correlation function (0) = 0.25 at 220 K. Such single photon emitters are promising for secure free space optical communication lines.
Highlights
Nanoantenna for the Visible SpectralQuantum information and communication systems require non-classical light sources that can emit, upon request, either one photon or a pair of entangled single photons with high external quantum efficiency at a certain frequency [1,2]
Single-photon emission can be obtained in a wide spectral range from medium ultraviolet to the optical telecommunication C-band (1.55 μm) through optical pumping of single quantum dots (QDs) fabricated in different material systems [4,5,6,7,8]
We have demonstrated successful operation in the visible range of single photon sources with CdSe QDs and purely semiconductor multimode optical nanoantennas
Summary
Quantum information and communication systems require non-classical light sources that can emit, upon request, either one photon or a pair of entangled single photons with high external quantum efficiency at a certain frequency [1,2]. QDs, the improved collection of the single-QD emission is usually achieved by fabricating columnar micropillars with distributed GaAs/AlAs Bragg mirrors consisting of the layers with close lattice constants [21] The fabrication of such structures in the systems based on IIVI semiconductors is complicated by the absence of corresponding binary lattice-matched compounds. The mode propagation along the smoothly tapered cylindrical waveguide ensures its adiabatic conversion into a strongly deconfined mode with a narrower, Gaussian-like far-field distribution This approach allows very high photon extraction efficiency (>90%) and their efficient collection by standard optics in a relatively wide spectral range of several tens of nanometers [23]. The experimental realization of the SPE with an average radiation rate exceeding 5 MHz at a practically important temperature of 220 K confirms the fruitfulness of this approach
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