Correlations between axial and lateral emission of coupled quantum dot-micropillar cavities
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We report on optical studies of coupled quantum dot–micropillar cavities using a 90∘ excitation-and-detection scheme. This specific configuration allows us to excite the micropillar structures either in the axial direction or in the lateral direction and to simultaneously detect emission from both directions. That enables us to reveal correlations between emission into the cavity mode and the leaky modes in the regime of cavity quantum electrodynamics. In particular, we can access and distinguish between axial cavity emission and lateral emission consisting of emission of quantum dots into the leaky modes and losses due to sidewall scattering, respectively. In the multiemitter regime, this technique provides direct access to the respective loss channels and reveals a strong increase of sidewall losses in the low-diameter regime below about 3.0 μm. Beyond that, in the single-emitter regime, we observe an anticorrelation between quantum dot emission coupled into the cavity mode and into the leaky modes which is controlled by light-matter interaction in the weak coupling regime. This anticorrelation is absent in the strong coupling regime due to the presence of entangled light-matter states. Moreover, excitation-power-dependent studies demonstrate that the intensity ratio between axial and lateral emission increases strongly above the lasing threshold due to enhanced directionality of emission into the lasing mode. In fact, theoretical studies confirm that this intensity ratio is an additional indicator of laser action in high-β microlasers for which the onset of lasing is difficult to identify by the input-output characteristics.
Musiał , A , Hopfmann , C , Heindel , T , Gies , C , Florian , M , Leymann , H A M , Foerster , A , Schneider , C , Jahnke , F , Höfling , S , Kamp , M & Reitzenstein , S 2015 , ' Correlations between axial and lateral emission of coupled quantum dot-micropillar cavities ' Physical Review. B, Condensed matter and materials physics , vol 91 , no. 20 , 205310 , pp. 1-10 . DOI: 10.1103/PhysRevB.91.205310
Physical Review. B, Condensed matter and materials physics
©2015 American Physical Society. This work is made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at https://dx.doi.org/10.1103/PhysRevB.91.205310
The authors acknowledge financial support by the German Research Foundation via Projects No. Ka2318/4-1 and No. Re2974/3-1, the SFB 787 “Semiconductor Nanophotonics: Materials, Models, Devices,” and the State of Bavaria.