Wednesday 21 October; Delft, Jean-Michel Gerard 'A high-brightness single photon source based on a quantum dot in a photonic nanowire'



Time: 16:00 hrs

Location Room E

CEA Grenoble/INAC/SP2M/ Joint CEA-CNRS group "Nanophysique et Semiconducteurs"

I will present a novel single-photon-source (SPS) based on the emission of a semiconductor quantum dot embedded in a single-mode photonic wire. This geometry ensures a very large coupling (>95%) of the spontaneous emission to the guided mode. Numerical simulations [1] show that a photon collection efficiency as large as 90% can be obtained for engineered nanowires with a tapered tip [2] and a metallic bottom mirror coated by a thin dielectric layer [3]. Experimentally, a record-high efficiency of 75 ±7% (for a NA=0.75 collection optics) has been measured for an InAs quantum dot embedded in such a nanowire, made of GaAs and defined by reactive-ion etching [4]. Unlike SPS based on resonant cavities, such sources also display a very pure single photon emission (g(2)(0)< 0.01).

In the context of SPS, this novel approach, which provides spontaneous emission control over a wide spectral band, offers several important assets compared to cavity-based ones: 1) it can easily be applied to non-monochromatic emitters such as F-centers in diamond (or QDs at high temperature); 2) it is well suited to the development of wavelength tuneable SPS; 3) it is finally also very attractive for developing electrically pumped SPS; we will present original designs which should permit reaching SPS efficiencies well above 80%, whereas the best reported value to date is around 15%.

[1] I. Friedler et al : Solid-state single photon sources: the nanowire geometry, Opt. Exp. 17, 2095 (2009)

[2] N. Gregersen et al : Controlling the emission profile of a nanowire with a conical taper, Opt. Lett. 33, 1693-1695 (2008)

[3] I. Friedler et al : Efficient photonic mirrors for semiconductor nanowires, Opt. Lett. 33, 2635 (2008)

[4] J. Claudon et al, subm. Nature Photon.