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We report fluorescence investigations and Raman spectroscopy on colloidal nanodiamonds (NDs) obtained via bead assisted sonic disintegration (BASD) of a polycrystalline chemical vapor deposition film. The BASD NDs contain in situ created silicon vacancy (SiV) centers. Whereas many NDs exhibit emission from SiV ensembles, we also identify NDs featuring predominant emission from a single bright SiV center. We demonstrate oxidation of the NDs in air as a tool to optimize the crystalline quality of the NDs via removing damaged regions resulting in a reduced ensemble linewidth as well as single photon emission with increased purity. We furthermore investigate the temperature dependent zero-phonon-line fine-structure of a bright single SiV center as well as the polarization properties of its emission and absorption. [ABSTRACT FROM AUTHOR]

Nitrogen-vacancy (NV) centers feature outstanding properties such as a spin coherence time of up to 1 s as well as a level structure offering the possibility to initialize, coherently manipulate, and optically read-out the spin degree of freedom of the ground state. However, only about 3% of their photon emission is channeled into the zero phonon line (ZPL), limiting both the rate of indistinguishable single photons and the signal-to-noise ratio (SNR) of coherent spin-photon interfaces. We here report on the enhancement of the SNR of the optical spin read-out achieved by tuning the mode of a two-dimensional photonic crystal (PhC) cavity into resonance with the NV-ZPL. PhC cavities are fabricated by focused ion beam milling in thin reactive ion etched ultrapure single crystal diamond membranes featuring modes with Q-factors of up to 8250 at mode volumes below one cubic wavelength. NV centers are produced in the cavities in a controlled fashion by a high resolution atomic force microscope implantation technique. On cavity resonance, we observe a lifetime shortening from 9.0 ns to 8.0 ns as well as an enhancement of the ZPL emission by almost one order of magnitude. Although on resonance the collection efficiency of ZPL photons and the spin-dependent fluorescence contrast are reduced, the SNR of the optical spin read-out is almost tripled for the cavity-coupled NV centers. [ABSTRACT FROM AUTHOR]

We report on the production of nanodiamonds (NDs) with 70-80 nm size via bead assisted sonic disintegration (BASD) of a polycrystalline chemical vapor deposition film. The high crystalline quality NDs display intense narrowband (7 nm) room temperature luminescence at 738 nm from in situ incorporated silicon vacancy centers. We demonstrate bright, narrowband single photon emission with >100 000 cps. Due to the narrow fluorescence bandwidth as well as the near-infrared emission these NDs are also suitable as fluorescence labels with significantly enhanced performance for in vivo imaging. [ABSTRACT FROM AUTHOR]

We investigate cavity-quantum electrodynamics (QED) effects in an all-semiconductor nanostructure by tuning a single self-assembled InAs quantum dot (QD) into resonance with a high quality factor microdisk whispering gallery mode (WGM). The stronger temperature dependence of the QD single-exciton (1X) resonance allows us to change the relative energy of the WGM and the 1X transitions by varying the sample temperature. The two coupled resonances exhibit crossing behavior due to the weak coupling cavity-QED regime. We demonstrate exciton lifetime reduction by 6 due to the Purcell effect by tuning the QD into resonance with the WGM. Our experiments also show that single-exciton lifetime is independent of temperature up to 50 K. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report the use of self-assembled InAs quantum dots as active emitters in a photonic crystal microcavity. We have fabricated defect microcavities by removing 37 and 61 air holes from a triangular lattice in a photonic crystal membrane, and obtained quality factors in excess of 1000. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report optically pumped continuous-wave lasing from self-assembled InAs and InGaAs quantum dots (QDs) embedded in high-quality-factor microdisk laser structures. The microdisk emission spectra show lasing on 1-5 well separated modes in the wavelength range between 900 and 990 nm. The estimated threshold pump densities are between 20 and 200 W/cm[sup 2]. The lasing characteristics are discussed in terms of both inhomogeneously and homogeneously broadened QD transitions. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]