Optically addressable spin defects hosted in two-dimensional van der Waals materials represent a new frontier for quantum technologies, promising to lead to a new class of ultrathin quantum sensors and simulators. Recently, hexagonal boron nitride (hBN) has been shown to host several types of optically addressable spin defects, thus offering a unique opportunity to utilise various spin species in a single material. Here we demonstrate the co-existence of two separate spin species within a single hBN powder sample, namely boron vacancy defects and visible emitter spins. To identify the two spin species, we studied photoluminescence (PL) and optically detected magnetic resonance (ODMR) spectra for the as-received commercially sourced hBN powder and after electron irradiation. Further, we prepared a film of hBN powder on a test magnetic sample (a patterned CoFeB film with in-plane magnetization) and used the hBN spins to spatially map the sample’s stray magnetic field at room temperature.Our results establish hBN as a versatile platform for quantum technologies in a van der Waals host at room temperature.
The fabrication of a stable, reproducible optical imaging phantom is critical to the assessment and optimization of optical imaging systems. In this study, we present a novel design of optical phantom based on metal-doped glass-ceramics. The matrix was doped with nickel ions to imitate the absorption of haemoglobin, and scattering levels representative of tissue were induced through controlled crystallisation in the glass-based phantom at elevated temperature. Our glass-based optical phantom can provide controlled levels of optical scattering and absorption to mimic the optical properties of human tissues with excellent optical homogeneity, and potentially long-term stability and reproducibility.
We demonstrate fabrication and characterizations of intrinsically magneto-sensitive fiber with potential applications as a high-efficiency remote magnetic field sensing platform. The fibre was fabricated using lead-silicate glass and the rod-intube fibre drawing technique. The thin glass rod of ~1 mm diameter was first coated with nitrogen-vacancy (NV) centreenriched diamond particles of ~1 μm diameter, and subsequently inserted into the glass outer tube. This rod-in-tube assembly was drawn down to fibre, with the diamond particles distributed at the fused interface between rod and tube. We experimentally coupled 532 nm continuous-wave laser into a 30-cm-length fibre piece from the fibre endface, and examined the photoluminescence (PL) properties of the fibre from both the side of the fibre and the output end of the fibre. PL mapping results showed that the glass-embedded NV emitters showed bright and photostable fluorescence, demonstrating characteristic NV centre zero phonon line emission. Moreover, the mapping result obtained at the output end of fibre indicated that the transmitted NV fluorescence was coupled into the propagation modes of the fibre. By using optically detected magnetic resonance (ODMR) from the NV ensemble along the fibre, we demonstrate detection of local magnetic fields via longitudinal excitation and side collection. Based on the current light transmission and collection configuration, the hybrid diamond-glass optical fibre sensor demonstrated a shot noise-limited DC magnetic field sensitivity of 3.7 μT/√Hz at room temperature. Our results open the possibility of robust, field-deployable fibre optical magnetometry.
This work reports nanodiamond-silk membranes as an optical platform for biosensing and cell growth applications. The hybrid structure was fabricated through electrospinning and mimics a 2D scaffold with high porosity. The negatively charged nitrogen vacancy (NV-) centres in diamond exhibits optically detected magnetic resonance (ODMR), which enables sensing of temperature variations. The NV- centre, as reported in literature, provides a shift of 74 kHz in the ODMR frequency per degree rise in temperature. For our hybrid membranes, we have however observed that the embedded NV- centre provide a greater shift of 95±5 kHz/K in the ODMR frequency. This higher shift in the frequency will result in improved temperature sensitivity enabling the tracking of thermal variations in the biologically relevant window of 25-50 ºC. The thermal conductivity of silk and diamond-silk hybrid will be explored to investigate this enhanced temperature sensing ability of diamond. The hybrid diamond-silk membranes are found to be hydrophilic with a contact angle of (65±2)º. The biocompatibility of the membranes is tested both in vitro in skin keratinocyte (HaCaT) cells and in vivo in a live mouse wound model. The membranes did not induce any toxicity to the cell growth and survival. Moreover, we observed resistance towards the growth and attachment of bacteria.
The nitrogen-vacancy (NV) centre in diamond is a perfect candidate for quantum sensing applications applied to numerous fields of science. Past studies improved the sensitivity of diamonds containing NV centres by increasing their density or prolonging their coherence time. However, few studies discussed the effects of other defects inside the diamond crystal on the sensitivity of the NV centres. In this study, we demonstrated the implication of single substitutional nitrogen defects on the fluorescence emission, charge state stability, coherence time and sensitivity of the NV centres. We found that there is an optimal concentration of nitrogen defects that allows diamond samples to have a high-density of NV centres and high fluorescence without significantly affecting the coherence time. This results will inform the correct choice of diamond characteristics for current and future quantum sensing applications with the NV centres.
Fluorescent nanodiamonds made from high-pressure high-temperature diamond are increasingly used in biological imaging and sensing applications. To date, only red and green fluorescent nanodiamonds are widely available, severely limiting nanodiamond-based multiplexed imaging. Here, we report on recent progress in the fabrication and characterization of fluorescent nanodiamonds with fluorescence colors from 450 nm to 900 nm. The fluorescence originates from a range of fluorescent color centers based on nitrogen, silicon, nickel and vacancy defects in the diamond lattice. The optical properties of these color centers in diamond nanoparticles are discussed in detail and the utility of nanodiamond-based multiplexed bioimaging demonstrated in experiments in-vitro.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.