447 research outputs found
Imaging and quantum efficiency measurement of chromium emitters in diamond
We present direct imaging of the emission pattern of individual
chromium-based single photon emitters in diamond and measure their quantum
efficiency. By imaging the excited state transition dipole intensity
distribution in the back focal plane of high numerical aperture objective, we
determined that the emission dipole is oriented nearly orthogonal to the
diamond-air interface. Employing ion implantation techniques, the emitters were
engineered with various proximities from the diamond-air interface. By
comparing the decay rates from the single chromium emitters at different depths
in the diamond crystal, an average quantum efficiency of 28% was measured.Comment: 11 pages and 4 figure
Engineering chromium related single photon emitters in single crystal diamond
Color centers in diamond as single photon emitters, are leading candidates
for future quantum devices due to their room temperature operation and
photostability. The recently discovered chromium related centers are
particularly attractive since they possess narrow bandwidth emission and a very
short lifetime. In this paper we investigate the fabrication methodologies to
engineer these centers in monolithic diamond. We show that the emitters can be
successfully fabricated by ion implantation of chromium in conjunction with
oxygen or sulfur. Furthermore, our results indicate that the background
nitrogen concentration is an important parameter, which governs the probability
of success to generate these centers.Comment: 14 pages, 5 figure
Suppression of Spectral Diffusion by Anti-Stokes Excitation of Quantum Emitters in Hexagonal Boron Nitride
Solid-state quantum emitters are garnering a lot of attention due to their
role in scalable quantum photonics. A notable majority of these emitters,
however, exhibit spectral diffusion due to local, fluctuating electromagnetic
fields. In this work, we demonstrate efficient Anti-Stokes (AS) excitation of
quantum emitters in hexagonal boron nitride (hBN), and show that the process
results in the suppression of a specific mechanism responsible for spectral
diffusion of the emitters. We also demonstrate an all-optical gating scheme
that exploits Stokes and Anti-Stokes excitation to manipulate spectral
diffusion so as to switch and lock the emission energy of the photon source. In
this scheme, reversible spectral jumps are deliberately enabled by pumping the
emitter with high energy (Stokes) excitation; AS excitation is then used to
lock the system into a fixed state characterized by a fixed emission energy.
Our results provide important insights into the photophysical properties of
quantum emitters in hBN, and introduce a new strategy for controlling the
emission wavelength of quantum emitters
Design of photonic microcavities in hexagonal boron nitride
© 2018 Kim et al. We propose and design photonic crystal cavities (PCCs) in hexagonal boron nitride (hBN) for diverse photonic and quantum applications. Two dimensional (2D) hBN flakes contain quantum emitters which are ultra-bright and photostable at room temperature. To achieve optimal coupling of these emitters to optical resonators, fabrication of cavities from hBN is therefore required to maximize the overlap between cavity optical modes and the emitters. Here, we design 2D and 1D PCCs using anisotropic indices of hBN. The influence of underlying substrates and material absorption are investigated, and spontaneous emission rate enhancements are calculated. Our results are promising for future quantum photonic experiments with hBN
Photophysics of chromium-related diamond single-photon emitters
A detailed study of the photophysical properties of several chromium-related color centers produced within chemical vapor deposition diamond is presented. These emitters show narrow luminescence lines in the range of 740-770nm. Single-photon emission was verified with continuous and pulsed excitation with detected emission rates at saturation in the range of (2-3)×106 counts/s, while direct lifetime measurements reveal excited state lifetimes for the distinct centers ranging 1-14 ns. In addition, a number of quantum emitters demonstrate two-level behavior with no bunching present in the second-order correlation function. The three-level systems revealed typically photoluminescence lines with width half-maximum of ~4nm while the two-level emitters have full width half-maximum of ~10nm at room temperature. In addition, the quantum efficiency of the two-level system was measured to be four times higher than that of the three-level syste
Phonon-induced dephasing of chromium colour centres in diamond
We report on the coherence properties of single photons from chromium-based
colour centres in diamond. We use field-correlation and spectral lineshape
measurements to reveal the interplay between slow spectral wandering and fast
dephasing mechanisms as a function of temperature. We show that the zero-phonon
transition frequency and its linewidth follow a power-law dependence on
temperature indicating that the dominant fast dephasing mechanisms for these
centres are direct electron-phonon coupling and phonon-modulated Coulomb
coupling to nearby impurities. Further, the observed reduction in the quantum
yield for photon emission as a function of temperature is consistent with the
opening of additional nonradiative channels through thermal activation to
higher energy states predominantly and indicates a near-unity quantum
efficiency at 4 K
Fluorescent emission in different silicon carbide polytypes
Silicon carbide (SiC) is a widely used material in several industrial applications such as high power electronics, light emitting diodes, and in research application such as photo-voltaic and quantum technologies. As nanoparticles it can be synthetised in many sizes and different polytypes from 200 nm down to 1 nm. In the form of quantum dots they are used as optical biomarkers, and their emission, occurring from the blue to the orange spectral region, is based on quantum confinement effect. In this work we report on emission in the red and near infrared in different SiC polytypes, specifically in 4H, 6H and 3C. In 4H SiC the red visible emission yielded non classical light attributed to an intrinsic defect, identified as a carbon-antisite vacancy pair. Similar spectral emission was observed in 3C SiC bulk and nanoparticles, also yielding very bright single photon emission. Emission in the far red has been observed in homogeneous hetero-structure in SiC tetrapods. © 2013 Copyright SPIE
Observation of Whispering Gallery Modes from hexagonal ZnO microdisks using cathodoluminescence
Zinc oxide hexagonal microdisks with diameters ranging from 3??m up to 15??m were fabricated by thermal chemical vapour deposition. Optical characterisation of ZnO microdisks was performed using low temperature (80?K) cathodoluminescence (CL) imaging and spectroscopy. The microdisks exhibited green luminescence locally distributed near the hexagonal boundary of the ZnO microdisks. High resolution CL spectra of the ZnO microdisks revealed whispering gallery modes (WGMs) emission. The experimentally observed WGMs were in excellent agreement with the predicted theoretical positions calculated using a plane wave model. This work could provide the means for ZnO microdisk devices operating in the green spectral range
Maskless milling of diamond by a focused oxygen ion beam
Recent advances in focused ion beam technology have enabled high-resolution, maskless nanofabrication using light ions. Studies with light ions to date have, however, focused on milling of materials where sub-surface ion beam damage does not inhibit device performance. Here we report on maskless milling of single crystal diamond using a focused beam of oxygen ions. Material quality is assessed by Raman and luminescence analysis, and reveals that the damage layer generated by oxygen ions can be removed by non-intrusive post-processing methods such as localised electron beam induced chemical etching
Coupling of nitrogen-vacancy centers in diamond to a GaP waveguide
The optical coupling of guided modes in a GaP waveguide to nitrogen-vacancy
(NV) centers in diamond is demonstrated. The electric field penetration into
diamond and the loss of the guided mode are measured. The results indicate that
the GaP-diamond system could be useful for realizing coupled microcavity-NV
devices for quantum information processing in diamond.Comment: 4 pages 4 figure
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