Surface and subsurface evolution mechanism in continuous wave laser ablation process of Cf/SiC ceramic matrix composites: A multiscale investigation

Biophotonics─and more recently, biointegrated photonics─offer transformative tools for probing cellular processes with unprecedented precision. Among these, whispering-gallery-mode (WGM) resonators (optical microcavities formed in spherical structures) have emerged as powerful biosensors and intracellular barcodes. Lipid droplets (LDs), with their high refractive index and intrinsic spherical geometry, are ideal candidates for supporting intracellular lasing. Although lasing in LDs has been previously demonstrated, it has not yet been harnessed to study live-cell biology. Here, we report the first use of WGM resonances in LDs of live primary adipocytes, employing a continuous-wave (CW) laser at powers below the biological damage threshold. By measuring these resonances, we achieved nanometer-scale precision in size estimation, enabling real-time observation of rapid LD dynamics and deformations on the minute scale─far beyond the spatiotemporal resolution of conventional microscopy. We systematically characterized this photonic sensing approach, demonstrating its ability to resolve adipocyte heterogeneity, monitor lipolytic responses to forskolin and isoproterenol, and detect early signs of cell viability loss─well before conventional assays. This proof-of-concept establishes intracellular LD WGM resonances as a robust platform for investigating live single-cell metabolism. The technique enables rapid, cost-effective assessment of adipocyte function, reveals cell-to-cell variability obscured by bulk assays, and lays the foundation for high-throughput analysis of metabolism- and obesity-related diseases at both the cellular and tissue levels.

Measurement of low power infrared light emission spectra from microstructures can be challenging but is of key importance in several research fields. Fourier transform infrared (FTIR) spectrometers can be used for characterizing such weak light emitters, but this requires additional custom user calibration compared to traditional FTIR measurements of, e.g., transmission or reflection. These calibration techniques are well documented for standalone FTIR instruments but not for microscope-coupled FTIRs, even though such an architecture greatly simplifies the collection of light from micro- and nanoscale structures. We propose and demonstrate a calibration method for microscope-FTIRs based on the well-known emissivity of doped silicon at high temperatures. With this method, we measure the responsivity and noise floor of a recently installed microscope-FTIR instrument (Bruker© Invenio® R coupled with a Hyperion II microscope), which is found to be within theoretically predicted values. The method is demonstrated for two different detectors (mercury cadmium telluride and indium antimonide), in both continuous wave and modulated (step-scan) emission measurement modes.

Understanding the structure and dynamics of nucleic acids is essential for elucidating their complex biological functions. Electron Paramagnetic Resonance (EPR) spectroscopy is a valuable technique to extract such information. However, its application to nucleic acids requires the incorporation of spin labels, usually nitroxides. Rigid spin labels are more informative EPR probes than flexible ones, since they offer high-precision distance measurements and can provide information about the relative orientation of spin labels. However, the synthesis and incorporation of such rigid labels is nontrivial. Here we describe a strategy in which the rigid spin label Çm is incorporated into a small hairpin, which in turn can be used to label several different oligonucleotides noncovalently through helical stacking. We have studied the noncovalent assembly of spin-labeled RNA hairpins with RNA duplexes by both continuous wave (CW) and pulsed dipolar EPR spectroscopy, specifically pulsed electron-electron double resonance (PELDOR, also called DEER). Our data shows that short complementary overhangs facilitate efficient helical stacking, opening the possibility of using noncovalent labeling with Çm-modified hairpins in conjunction with pulsed dipolar EPR spectroscopy for structural studies of larger RNAs and RNA-protein complexes.

Abstract Current-injection lasing in the 1380-nm band under continuous-wave operation has been demonstrated in wafer-bonded vertical-cavity surface-emitting lasers fabricated using an Ar-fast atomic beam. As an under-display light source, the maximum optical output power from a single emitter reached the milliwatt level, and stable operation was achieved up to 110 °C. A Si interlayer at the bonding interface contributes to strengthening the bond between GaAs and InP, thereby improving device performance owing to its high technological potential. This approach holds promise for advancing data communication and silicon photonics based on heterogeneous materials combining group-III–V and -IV semiconductors.

ABSTRACT Perovskite plasmonic lasers form a unique class of ultracompact coherent luminescent sources with potential for transformative applications in super‐resolution imaging, display technologies, and on‐chip coherent light sources for nanophotonic integration. However, achieving low‐threshold operations such as continuous‐wave (CW) pumped perovskite plasmonic lasers at room temperature remains a challenge, which is mainly due to the inherently high losses in plasmonic nanocavities. Here, we report a room‐temperature, CW‐pumped perovskite plasmonic laser with a record‐low threshold of 2.26 mW/cm 2 . This breakthrough is achieved by using an optimized grating‐coupled surface plasmon polaritons (SPPs) nanocavity with suppressed losses that combines with the advantages of ultrahigh quality ( Q ) factor, intense resonance intensity, and modified interface, simultaneously. In addition, the angular dispersion characteristic of SPPs enables the wavelength‐tunable nanocavities. As a result, lasing actions with tunable wavelength and directional emissions are ensured by this SPPs nanocavity. By realising CW‐pumped perovskite lasing at room temperature with desired properties for plasmonic lasers, this work advances the development of plasmonic lasers and demonstrates effective manipulation of the luminescence of perovskites through a SPPs nanocavity.

Abstract High power InP-based diode lasers operating at 1470 nm have attracted considerable interest in various applications. In this paper, we report high-power lasers with varying stripe widths, which employ an extremely asymmetric epitaxial design for high-efficiency carrier injection and low optical loss. The characteristic temperature of the differential quantum efficiency (T1) exceeds 270 K. Single-emitter lasers with 200μm-wide aperture achieve over 10 W continuous-wave (CW) power at 20 ℃ and a peak wall-plug efficiency of 42%. The maximum CW power reaches 11.7 W in devices with 300 μm stripe width. The dependence of divergence angle on the current is investigated.

Abstract Several mechanisms for gravitational wave (GW) emission are believed to be associated with pulsar glitches. This emission may be split between long duration continuous waves and short duration bursts. In the Advanced LIGO era, searches for GWs associated with pulsar glitches have only considered continuous wave emission. The increasing sensitivity of the detectors and the prospects for future detectors suggest that astrophysically motivated analyses involving multiple mechanisms may be possible. Here, we present a framework for combining two simple models for GW emission - long duration continuous waves and short duration bursts - to derive more constraining astrophysical implications than a single model would allow. The best limits arise from using models that predict a specific amount of GW emission; however, there are relatively few models that make such predictions. We apply these methods to the December 2016 Vela pulsar glitch and make predictions for how well future observing runs and detectors would improve results. As part of this analysis, we performed a targeted search for GW bursts associated with this glitch and find no signal.

Non-contact heart rate estimation technology based on frequency-modulated continuous wave (FMCW) radar has garnered extensive attention in single-target scenarios, yet it remains underexplored in multi-target environments. Accurate discrimination of multiple targets and precise estimation of their heart rates constitute key challenges in the multi-target domain. To address these issues, we propose a novel scheme for multi-target heart rate estimation. First, a high-precision distance-bin selection (HDBS) method is proposed for target localization in the range domain. Next, multiple-input multiple-output (MIMO) array processing is combined with the Root-multiple signal classification (Root-MUSIC) algorithm for angular domain estimation, enabling accurate discrimination of multiple targets. Subsequently, we propose an efficient method for interference suppression and vital sign extraction that cascades variational mode decomposition (VMD), local mean decomposition (LMD), and wavelet thresholding (WT) termed as VLW, which enables high-quality heartbeat signal extraction. Finally, to achieve high-precision and super-resolution heart rate estimation with low computational burden, an improved fast iterative interpolated beamforming (FIIB) algorithm is proposed. Specifically, by leveraging the conjugate symmetry of real-valued signals, the improved FIIB algorithm reduces the execution time by approximately 60% compared to the standard version. In addition, the proposed scheme provides sufficient signal-to-noise ratio (SNR) gain through low-complexity accumulation in both distance and angle estimation. Six experimental scenarios are designed, incorporating densely arranged targets and front-back occlusion, and extensive experiments are conducted. Results show this scheme effectively discriminates multiple targets in all tested scenarios with a mean absolute error (MAE) below 2.6 beats per minute (bpm), demonstrating its viability as a robust multi-target heart rate estimation scheme in various engineering fields.

We present a diode-pumped continuous-wave (CW) Yb:YVO4 laser exhibiting wavelength tunability from 986 nm to 1119 nm, corresponding to a broad tuning range of 133 nm, one of the widest reported for any Yb-doped laser host. This performance was achieved by employing a low-loss, off-surface optic-axis birefringent filter, high-quality laser crystals, and optimized low-loss cavity optics, enabling smooth and stable wavelength tuning along both principal polarization axes (E//a: 986-1084 nm and E//c: 995-1119 nm). The system delivers CW output powers up to 3.75 W, with slope and optical-to-optical efficiencies reaching 70% and 48%, respectively. These results highlight Yb:YVO4 as an attractive gain medium for applications requiring broad tunability, compactness, and efficiency, such as ultrafast pulse generation, broadband spectroscopy, and high-energy amplifier seeding.

With the rapid advancement of unmanned aerial vehicle (UAV) technology and its wide application in modern warfare, UAV feature extraction has become increasingly prominent. However, during actual feature extraction processes, raw echo data are susceptible to interference from complex environmental noise, making it difficult to directly obtain feature information of UAVs. In this work, a hybrid CLEAN filtering algorithm and terahertz radar are introduced for feature extraction of the multi-rotor UAV. First, we use terahertz frequency modulated continuous wave radar to obtain scanning imaging of low altitude hovering multi-rotor UAVs. Subsequently, a bandpass filtering method is applied to determine target positions while dynamic filtering with an improved CLEAN algorithm is integrated to effectively eliminate noise. Finally, bilateral filtering is used to enhance edges and clearly delineate target contours. When conducting experiments with multi-rotor UAVs of DJI Mavic3 and DJI Mini3 at a distance of no more than 10 m, the height error is within 30 mm and the width error is less than 40 mm, respectively. The proposed method improves the identification capability of terahertz radar for “low, small, slow” targets.

Multiphysics analysis of cryogenically cooled photocathode in a continuous wave SRF injector cavity

Precise and rapid oxygen sensing is crucial in a wide range of applications, from industrial process control to environmental monitoring and medical devices. In this proof-of-concept study, we present a new type of gas-phase oxygen sensing system that combines electron paramagnetic resonance (EPR) detection with a custom-designed sensing material: a metal-organic framework ZIF-8 composite with an embedded nitroxide spin probe. To enhance the sensing performance, we adapted the continuous wave EPR experiment protocol and optimized both the material structure and the gas delivery system. Static and flow experiments with dynamic exchange of the analyzed gas mixture were carried out. The sensing system significantly outperforms commercially available industrial models. It demonstrated reliable detection over a broad oxygen concentration range (0.02 to 95%) and response times from 550 ms to 2 s without sacrificing the accuracy. Due to detection simplicity, the sensor module can be further optimized by embedding it into an EPR-on-a-chip device, reducing the price and the module size. The integration of spin probes into a porous engineered framework offers a powerful approach for developing accurate and tunable oxygen sensors, which can meet the demands of both industry and research.

Doubly resonant optical parametric oscillators (OPOs) under continuous-wave (CW) pumping are particularly notable for their low threshold and narrow linewidth. Backward OPOs (BOPOs) realized through backward quasi-phase matching, which exhibit unique tuning properties compared with conventional forward OPOs, have been demonstrated under pulsed pumping. In this work, a doubly resonant BOPO was implemented in a semi-monolithic cavity under CW pumping, and its tuning properties were characterized. By tuning the pump wavelength, the forward and backward waves exhibited tuning rates of 1.02 and -0.02, respectively. Adjusting the crystal temperature resulted in tuning rates of 3 GHz/K and -3 GHz/K for the forward and backward waves, respectively. This research establishes the BOPO as a promising candidate for applications in the field of CW OPOs.

We report on heterogeneously integrated continuous-wave (CW) lasers on a SiN platform that employ a microgear as a wavelength-selective reflector. Heterogeneous integration is realized through micro-transfer printing (µTP), enabling compact, robust, and frequency-stable on-chip lasers without the need for phase shifters. The devices achieve up to 12.1 mW of on-chip optical output power and intrinsic linewidths as narrow as 3.7 kHz, highlighting the tradeoff between output coupling and coherence. The laser devices operate in single mode with side-mode suppression ratios exceeding 45 dB, and have a compact footprint of 4000 × 250 µm2. These results demonstrate a promising path to integrated lasers for coherent communications and LiDAR.

At Wendelstein 7-X (W7-X), the world's largest superconducting stellarator with a five-fold symmetry and reduced neoclassical transport, a broad suite of microwave diagnostics is installed and operated. Due to the robustness of in-vessel components and transmission lines against the harsh environment in fusion devices, they are candidates for reactor plasma control.This presentation will show an overview of microwave diagnostics at W7-X. After introducing the governing equations for the propagation of microwaves in a fusion plasma e.g. the determination of the local positions where the measurements are performed, the different diagnostics are presented. The presentation will encompass the installed diagnostics, but also, the planned upgrades and show important technical details and highlighting results obtained during the last campaigns. It will cover passive microwave diagnostics for the estimation of the electron temperature profile by radiometry from the 2nd and 3rd harmonic of the electron cyclotron emission (ECE) with a temporal resolution in the MHz-range. Furthermore, the 1st–3rd harmonic ECE radiation is measured with interferometry for both, X- and O-mode polarization. Also, fluctuations of the electron temperature are measured by various methods of correlation ECE. Active probing radar applications, so-called reflectometry, are installed to measure density fluctuations and its propagation. They allow measuring the turbulence propagation for a wide wavenumber range. Under certain assumptions the radial electric field, an important quantity for the neoclassical transport is deduced from this propagation. To measure the electron density profile in the edge, a frequency modulated continuous wave reflectometer is installed in the Ion Cyclotron Resonance Heating (ICRH)-antenna. The purpose of the instrument is the measurement of the density profile to improve the coupling of the ICRH-waves into the plasma. Besides this, the measurement of the density profile in the edge with high spatial and temporal resolution is independent of the ICRH-operation. Furthermore, a microwave scattering diagnostic, the collective Thomson Scattering (CTS), uses a gyrotron as active probing beam yields direct information of the ion temperature of hydrogen or in later campaigns deuterium species and does not rely on the impurity temperature.

A collective Thomson scattering (CTS) diagnostic system has been commissioned to measure the ion features of the jet plasma region of X-pinch plasma, including electron temperature, ion temperature, electron density, average charge state, and plasma bulk velocity. Due to the inherent nature of CTS, signals with two peaks within a very narrow wavelength range are observed, depending on the ion motion. To analyze CTS signals, a spectrometer with a high dispersion and high resolution is required. Accordingly, the spectrometer was designed and installed with a dispersion of 0.004 nm/pixel. Stray light at the laser wavelength (532 nm) must be carefully suppressed in an extremely narrow spectra range, while minimizing the spectral loss of the CTS signals. To achieve this, a volume Bragg grating narrow notch filter (optical density of 4) was installed at the entrance of the spectrometer. For the fine tuning of the optical alignment and for spectral calibration, the rotational Raman scattering spectrum was measured under atmospheric conditions (N2: 78%, O2: 21%). The spectral resolution, including instrumental broadening, was evaluated using a continuous wave laser with the wavelength of 532 nm transmitted through neutral density filters. The measured full width at half maximum is 0.0813 nm. The CTS signal from the jet region of the X-pinch plasma was successfully measured with the developed system. The theoretical CTS spectral density function, convolved with the spectral resolution, was compared with the measured CTS signal, and the characteristics of plasma jet were quantitatively analyzed.

Thermal Behaviour of Teeth With Internal Root Resorption During Obturation and Enhancing Thermal Simulations: A Finite-Element Analysis.

A comparison of the effect of SMA derivatives on the structural topology and dynamics of two bacteriophage peptides.

Although "ghost" imaging has seen remarkable advances since it was first studied 30 years ago, there have been few studies on x-ray ghost imaging (XGI) due to technical difficulties. A chief potential advantage of XGI is that imaging can be achieved with much lower radiation intensity. However, in previous XGI experiments with continuous wave x-ray illumination, the total sampling time was actually quite long, leading to additional radiation dose accumulation. In this paper, we report a proof-of-concept experiment using a high-sensitivity single-pixel detector together with a simple tabletop x-ray source followed by an adjustable mechanical shutter, which could reduce the total exposure time to as little as 5ms. Imaging was realized with a spatial resolution of 100μm under a low radiation dose. The influence of x-ray tube current, sampling frequency, and exposure times on image quality was examined. Our experiment illustrates a practical method for low-radiation dose ghost imaging and provides valuable reference data for the future development of medical XGI cameras.