264 research outputs found
Amplified Sensitivity of Nitrogen-Vacancy Spins in Nanodiamonds using All-Optical Charge Readout
Nanodiamonds containing nitrogen-vacancy (NV) centers offer a versatile
platform for sensing applications spanning from nanomagnetism to in-vivo
monitoring of cellular processes. In many cases, however, weak optical signals
and poor contrast demand long acquisition times that prevent the measurement of
environmental dynamics. Here, we demonstrate the ability to perform fast,
high-contrast optical measurements of charge distributions in ensembles of NV
centers in nanodiamonds and use the technique to improve the spin readout
signal-to-noise ratio through spin-to-charge conversion. A study of 38
nanodiamonds, each hosting 10-15 NV centers with an average diameter of 40 nm,
uncovers complex, multiple-timescale dynamics due to radiative and
non-radiative ionization and recombination processes. Nonetheless, the
nanodiamonds universally exhibit charge-dependent photoluminescence contrasts
and the potential for enhanced spin readout using spin-to-charge conversion. We
use the technique to speed up a relaxometry measurement by a factor of
five.Comment: 13 pages, 14 figure
Single-Mode Optical Waveguides on Native High-Refractive-Index Substrates
High-refractive-index semiconductor optical waveguides form the basis for modern photonic integrated circuits (PICs). However, conventional methods for achieving optical confinement require a thick lower-refractive-index support layer that impedes large-scale co-integration with electronics and limits the materials on which PICs can be fabricated. To address this challenge, we present a general architecture for single-mode waveguides that confine light in a high-refractive-index material on a native substrate. The waveguide consists of a high-aspect-ratio fin of the guiding material surrounded by lower-refractive-index dielectrics and is compatible with standard top-down fabrication techniques. This letter describes a physically intuitive, semi-analytical, effective index model for designing fin waveguides, which is confirmed with fully vectorial numerical simulations. Design examples are presented for diamond and silicon at visible and telecommunications wavelengths, respectively, along with calculations of propagation loss due to bending, scattering, and substrate leakage. Potential methods of fabrication are also discussed. The proposed waveguide geometry allows PICs to be fabricated alongside silicon CMOS electronics on the same wafer, removes the need for heteroepitaxy in III-V PICs, and will enable wafer-scale photonic integration on emerging material platforms such as diamond and SiC
Optical Signatures of Quantum Emitters in Suspended Hexagonal Boron Nitride
Hexagonal boron nitride (h-BN) is a tantalizing material for solid-state
quantum engineering. Analogously to three-dimensional wide-bandgap
semiconductors like diamond, h-BN hosts isolated defects exhibiting visible
fluorescence, and the ability to position such quantum emitters within a
two-dimensional material promises breakthrough advances in quantum sensing,
photonics, and other quantum technologies. Critical to such applications,
however, is an understanding of the physics underlying h-BN's quantum emission.
We report the creation and characterization of visible single-photon sources in
suspended, single-crystal, h-BN films. The emitters are bright and stable over
timescales of several months in ambient conditions. With substrate interactions
eliminated, we study the spectral, temporal, and spatial characteristics of the
defects' optical emission, which offer several clues about their electronic and
chemical structure. Analysis of the defects' spectra reveals similarities in
vibronic coupling despite widely-varying fluorescence wavelengths, and a
statistical analysis of their polarized emission patterns indicates a
correlation between the optical dipole orientations of some defects and the
primitive crystallographic axes of the single-crystal h-BN film. These
measurements constrain possible defect models, and, moreover, suggest that
several classes of emitters can exist simultaneously in free-standing h-BN,
whether they be different defects, different charge states of the same defect,
or the result of strong local perturbations
High Contrast 50kV E-Beam Lithography for HSQ atop Diamond using ESPACER for Spin-On Charge Dissipation
A high contrast HSQ process atop diamond is presented. A water soluable spin-on conductive layer called ESPACER is used as a charge dissipation layer in lieu of a metal thin film
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