DETERMINISTIC QUANTUM WIRE AND DOT SYSTEMS FOR NANOPHOTONIC AND LASER APPLICATIONS
Eli Kapon
Ecole Polytechnique Fédérale de Lausanne (EPFL)
Laboratory of Physics of Nanostructures, 1015 Lausanne, Switzerland eli.kapon@epfl.ch
Incorporating semiconductor quantum nanostructures such as quantum wires (QWRs) and quantum dots (QDs) into nano- photonic elements is of interest for both fundamental quantum photonics research and for applications in new photonic devices and systems. Examples include solid-state quantum information science and technology1 and ultra-low-power lasers for optical computer interconnects. However, most work in this field has been carried out using self-assembled QDs, which do not provide the highly demanding spatial and spectral control required for such integration.
Here, we report recent progress in the integration of ordered systems of pyramidal QDs and V-groove QWRs, grown on patterned substrates, with nano-photonic cavities. The site-controlled (In)GaAs/(Al)GaAs QDs exhibit exceptional uniformity (~1meV inhomogeneous broadening)2, and their heterostructure potential can be tailored in great detail. Their high C3v symmetry facilitates the generation of polarization-entangled photons with high yield3. Integration of both site-controlled V-groove QWRs and pyramidal QDs with photonic crystal (PhC) membrane cavities has been demonstrated4. Short (~1µm) QWR-PhC cavity lasers (see Figure) show sub-µW thresholds under optical pumping and dynamic effects inherent to the small number of carriers and photons involved in lasing5. Single pyramidal QDs integrated into photonic crystal (PhC) membrane cavities exhibit uniquely near-resonance, phonon mediated coupling6. More recently, PhC cavities loaded with a measurable number of QDs (from 2 to
~50) have also been studied, being candidates for laser structures incorporating dots that all interact with the same optical cavity mode7. Such QD systems showing reproducible emission spectra, as well as evidence for their simultaneous coupling to mutual cavity modes, will be described and discussed.
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3A. Mohan et al., Nature Photonics, 4, 302 (2010); M.-A. Dupertuis et al., Phys. Rev. Lett. 107, 7403 (2011).
4K. Atlasov et al., Appl. Phys. Lett. 90, 153107 (2007); P. Gallo et al., Appl. Phys. Lett. 92, 63101 (2008).
5 K. Atlasov et al., Opt. Express 17, 18178 (2009).
6M. Calic et al., Phys. Rev. Lett. 106, 227402 (2011).
7A. Surrente et al., Nanotechnology 22, 5203 (2011).
Figure. AFM image, TEM cross-section and emission spectra of a QWR-PhC laser5.