No abstract

The negatively-charged nitrogen vacancy center (NV) in diamond has generated significant interest as a platform for quantum information processing and sensing in the solid state. For most applications, high quality optical cavities are required to enhance the NV zero-phonon line (ZPL) emission. An outstanding challenge in maximizing the degree of NV-cavity coupling is the deterministic placement of NVs within the cavity. Here, we report photonic crystal nanobeam cavities coupled to NVs incorporated by a delta-doping technique that allows nanometer-scale vertical positioning of the emitters. We demonstrate cavities with Q up to ~24,000 and mode volume V ~ 0.47(λ/n) 3 as well as resonant enhancement of the ZPL of an NV ensemble with Purcell factor of ~20. Our fabrication technique provides a first step towards deterministic NV-cavity coupling using spatial control of the emitters.A diamond-based emitter-cavity system provides an important platform for the realization of quantum information processing and sensing in the solid state 1-4 . The long electron spin coherence of the negatively-charged nitrogen vacancy center (subsequently referred to as NV) in

InGaN-based active layers within microcavity resonators offer the potential of low threshold lasers in the blue spectral range. Here we demonstrate optically pumped, room temperature lasing in high quality factor GaN microdisk cavities containing InGaN quantum dots (QDs) with thresholds as low as 0.28 mJ/cm 2 . This work, the first demonstration of lasing action from GaN microdisk cavities with QDs in the active layer, provides a critical step for the nitrides in realizing low threshold photonic devices with efficient coupling between QDs and an optical cavity.

Films of semiconductor quantum dots (QDs) are promising for lighting technologies, but controlling how current flows through QD films remains a challenge. A new design for a QD light‐emitting device that uses atomic layer deposition to fill the interstices between QDs with insulating oxide is introduced. It funnels current through the QDs themselves, thus increasing the light emission yield.

Here we describe the fabrication and characterization of a plasmonic nanocavity formed in the narrow gap between a Ag nanowire and a flat Ag substrate. The fluorescence spectrum of nanocrystals within the gap was strongly modified by the cavity modes, showing peaks of position and width (Q∼30–60) in quantitative agreement with numerical calculations. At gap spacings of ∼15 nm, the noncavity background fluorescence is largely quenched by the Ag substrate, while the modal fluorescence remains strong, indicating that gap-type structures are more robust to fluorescence quenching.

We conduct a comprehensive investigation into the electronic and magneto-transport properties of ZnO nanoplates grown concurrently with ZnO nanowires by the vapor-liquid-solid (VLS) method. We present magnetoresistance data showing weak localization in our nanoplates and probe its dependence on temperature and carrier concentration. We measure phase coherence lengths of 50-100 nm at 1.9 K, and, because we do not observe spin-orbit scattering through antilocalization, suggest that ZnO nanostructures may be promising for further spintronic study. We then proceed to study the effect of weak localization on electron mobility using 4-terminal van der Pauw resistivity and Hall measurements versus temperature and carrier concentration. We report an electron mobility of ∼100 cm 2 V s at 275 K, comparable to what is observed in ZnO thin films. We compare Hall mobility to field-effect mobility, which is more commonly reported in studies on ZnO nanowires, and find that field-effect mobility tends to overestimate Hall mobility by a factor of 2 in our devices. Finally, we comment on temperature-dependent hysteresis observed during transconductance measurements and its relationship to mobile, positively-charged Zn interstitial impurities.

We describe the fabrication and operation of a device which performs linear optical up-conversion at room temperature. The mechanism for up-conversion is based on internal photoemission from a Schottky contact. We then describe the voltage dependence of this device and interpret it in terms of total energy conservation. Although an AlGaAs/GaAs system is employed here, the functionality is not material-specific and therefore should be widely applicable to different materials systems, such as GaN/InGaN.

We present a 2-D plasmonic crystal design with visible band-gap by combining a 2-D photonic crystal with TM band-gap and a silver surface. Simulations show that the presence of the silver surface gives rise to an expanded band-gap. A plasmonic crystal defect cavity with Q ~300 and mode volume ~1.9x10(-2) (λ/n) (3) can be formed using our design. The total Q of such a cavity is determined by both the radiative loss of the dielectric component, as well as absorption loss to the metal. We provide design criteria for the optimization of the total Q to allow high radiative or extraction efficiency.