Control of the Spontaneous Emission in Semi-conducting Photonic Nanowires

Mathieu Munsch^a,d, J.Claudon^a, J. Bleuse^a, M. Creasy^a, N.S. Malik^a, E.Dupuy^a, Y. Chen^b, N. Gregersen^b, J. Mørk^b, I. Maksymov^c, J.P Hugonin^c, P. Lalanne^c and J-M. Gérard^a

^a CEA-CNRS-UJF group ‘Nanophysique et Semiconducteurs’, CEA, INAC, SP2M, F-38054 Grenoble, France
^b DTU Fotonik, Dpt of Photonics Engineering, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
^c Laboratoire Charles Fabry de l’Institut d’Optique, CNRS, Université Paris-Sud, Campus Polytechnique, RD 128, 91127 Palaiseau, France
^d Quantum Optics Lab, University of Basel, Switzerland

Photonic nanowires (PWs) are simple dielectric structures for which a very efficient and broadband spontaneous emission (SE) control has been predicted [1]. Recently, a single photon source featuring a record high efficiency was demonstrated using this geometry [2]. Using time-resolved micro-photoluminescence, we investigate directly the SE of single InAs QDs embedded in GaAs PWs and demonstrate performances that fully confirm the theoretical predictions [3]. In addition, we discuss recent results obtained on elliptical wires that ensure an efficient control of the photon polarization [4].
We first consider cylindrical PWs, defined within a top-down fabrication process. For diameters leading to the optimal confinement of the fundamental guided mode HE11 (d/~0.25, ~950nm), the coupling to HE11 (2-time polarization degenerated) dominates the SE process and a maximum enhancement of the SE rate by a factor of 1.5 is reached . When the diameter is decreased by 100nm, the guided mode is completely deconfined. The coupling to this mode vanishes, thus allowing the coupling to the other radiation modes to be probed [3]. In these conditions, a SE inhibition factor of 16, equivalent to the one obtained in state-of-the-art 2D photonic crystals, is measured.
 Moreover, a PW featuring an elliptical section provides a very efficient control over the polarization of the emitted photon. In that case, only one guided mode, with a linear polarization oriented along the major axis, is confined in the semiconductor. Polarization-resolved experiments show that the coupling to this single mode can exceed 95% for optimum structures [4]. These results confirm the high potential of PWs for the realization of efficient sources of quantum light.

References
[1] I. Friedler et al. Opt. Express, 17, 2095 (2009)
[2] J. Claudon et al. Nature Photonics. 4, 174 (2010)
[3] J. Bleuse et al. Phys Rev Lett, 106, 103601 (2011)
[4] M. Munsch et al., PRL108, 077405 (2012)