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The potential of Ge nanoparticles (NPs) embedded in Al2O3 with tunable effective optical bandgap values in the range of 1.0-3.3 eV to induce enhanced Er3+ light emission is investigated. We demonstrate nonresonant indirect excitation of the Er3+ ions mediated by the Ge NPs at room temperature. Efficient Er3+ light emission enhancement is obtained for Ge NPs with large effective optical bandgaps in the range of 1.85 to 2.8 eV. The coupled Ge NP-Er emission shows a negligible thermal quenching from 10 K to room temperature that is related to Er3+ de-excitation through thermally activated defect states.

We investigate L7 photonic crystal microcavities (PCMs) fabricated by epitaxial re-growth of GaAs pre-patterned substrates, containing InAs quantum dots. The resulting PCMs show hexagonal shaped nano-holes due to the development of preferential crystallographic facets during the re-growth step. Through a careful control of the fabrication processes, we demonstrate that the photonic modes are preserved throughout the process. The quality factor (Q) of the photonic modes in the re-grown PCMs strongly depends on the relative orientation between photonic lattice and crystallographic directions. The optical modes of the re-grown PCMs preserve the linear polarization and, for the most favorable orientation, a 36% of the Q measured in PCMs fabricated by the conventional procedure is observed, exhibiting values up to ~6000. The results aim to the future integration of site-controlled QDs with high-Q PCMs for quantum photonics and quantum integrated circuits.

The spontaneous emission rate and Purcell factor of self-assembled quantum wires embedded in photonic crystal micro-cavities are measured at 80 K by using micro-photoluminescence, under transient and steady state excitation conditions. The Purcell factors fall in the range 1.1 - 2 despite the theoretical prediction of ≈15.5 for the figure of merit. We explain this difference by introducing a polarization dependence on the cavity orientation, parallel or perpendicular with respect to the wire axis, plus spectral and spatial detuning factors for the emitters and the cavity modes, taking in account the finite size of the quantum wires.

We present laser emission of a compact surface-emitting micro laser, optical pumped and operating at 1.5 microm at room temperature. A two-dimensional photonic crystal lattice conformed in a hybrid triangular-graphite configuration is designed for vertical emission. The structures have been fabricated in an InP slab, including four InAsP quantum wells as active layer, on the top of a Si substrate SiO(2) wafer bonded. Laser emission with thresholds around 70 microW and quality factors (Qs) up to 12000 have been measured. The Bloch mode selected for the emission keeps a high Q (>or= 2 x 10(5)) around the Gamma point for a wide range of in-plane values k(||)

We present continuous wave laser emission in a photonic crystal microcavity operating at 1.5 microm at room temperature. The structures have been fabricated in an InP slab including a single layer of self-assembled InAs/InP quantum wires (QWrs) as active material. Laser emission in air suspended membranes with thresholds of effective optical pump power of 22 microW and quality factors up to 55000 have been measured., ((c) 2009 Optical Society of America)