Single-shot, multi-point remote gas sensing by a linearly chirped laser pulse.

We present a spectroscopic method that employs a single linearly chirped laser pulse (LCLP) generated by external modulation to realize long-distance multi-point gas sensing. Even without frequency-chirping calibration, accurate single-shot spectral measurement is rendered possible by the high linearity of intrapulse chirping (linearity error of ∼10). Utilizing the LCLP's built-in capacity of time-division-multiplexing, high measurement sensitivity is guaranteed by introducing a multichannel intensity noise compensation mechanism.

A dataset for fine-grained seed recognition.

The research of plant seeds has always been a focus of agricultural and forestry research, and seed identification is an indispensable part of it. With the continuous application of artificial intelligence technology in the field of agriculture, seed identification through computer vision can effectively promote the development of agricultural and forestry wisdom. Data is the foundation of computer vision, but there is a lack of suitable datasets in the agricultural field.

Fiber-optic immunosensor based on a Fabry-Perot interferometer for single-molecule detection of biomarkers.

Immunosensors capable of ultralow-concentration and single-molecule detection of biomarkers are garnering attention for the early diagnosis of cancer. Herein, a fiber-optic Fabry-Perot interferometer (FPI)-based immunosensor was used for the first time for single-molecule detection of progastrin-releasing peptide (ProGRP). The cascaded FPI structure of the immunosensor introduces a high-order harmonic Vernier effect (HVE).

Multiwavelength erbium-doped fiber laser using the polarization-hole-burning effect for multichannel acoustic detection.

We propose and demonstrate a novel, to the best of our knowledge, fiber-optic multipoint acoustic detection system based on a multiwavelength erbium-doped fiber (EDF) laser (MWEDFL) using the polarization-hole-burning effect with Fabry-Perot interferometers as the acoustic cavity-loss modulator. A polarization-wavelength-related filter is designed to assign a distinct polarization state to each laser wavelength. By adjusting the polarization state, the polarization-dependent loss and gain of each laser line are tuned to be equal, effectively suppressing the mode competition of EDF and enabling a stable MWEDFL.

Mussel-inspired electroactive, antibacterial and antioxidative composite membranes with incorporation of gold nanoparticles and antibacterial peptides for enhancing skin wound healing.

Large skin wounds are one of the most important health problems in the world. Skin wound repair and tissue regeneration are complex processes involving many physiological signals, and effective wound healing remains an enormous clinical challenge. Therefore, there is an urgent need for a strategy to rapidly kill bacteria, promote cell proliferation and accelerate wound healing.

ROS-scavenging materials for skin wound healing: advancements and applications.

The intricate healing process of skin wounds includes a variety of cellular and molecular events. Wound healing heavily relies on reactive oxygen species (ROS), which are essential for controlling various processes, including inflammation, cell growth, angiogenesis, granulation, and the formation of extracellular matrix. Nevertheless, an overabundance of reactive oxygen species (ROS) caused by extended oxidative pressure may result in the postponement or failure of wound healing.

Integrated nucleic acid purification technology based on amino-modified centrifugal microfluidic chip.

Nucleic acid detection is an important tool for clinical diagnosis. The purification of the sample is the most time-consuming step in the nucleic acid testing process and will affect the results of the assay. Here, we developed a surface modification-based nucleic acid purification method and designed an accompanying set of centrifugation equipment and chips to integrate the steps of nucleic acid purification on a single platform.

Fading suppression in the Ф-OTDR system based on a phase-modulated optical frequency comb.

In this paper, what we believe to be a novel method is proposed to suppress the fading effect of the phase-sensitive optical time domain reflectometer (Ф-OTDR) by using a phase-modulated optical frequency comb. In the Ф-OTDR system, intensity distributions of Rayleigh backscattering (RBS) light are different for pulsed probe lights with different central frequencies, therefore the locations of the fading points corresponding to signals of different frequencies are differently distributed, allowing the use of frequency division multiplexing to suppress the fading effects. In the experimental system of this paper, a continuous light in the form of a frequency comb is firstly generated through phase modulation.

Dynamic distributed optical fiber sensing based on simultaneous measurement of Brillouin gain and loss spectra with frequency-agile technique.

To simplify the experimental equipment and improve the signal-to-noise ratio (SNR) of the traditional Brillouin optical time-domain analysis (BOTDA) system, we propose a scheme using the frequency-agile technique to measure Brillouin gain and loss spectra simultaneously. The pump wave is modulated into the double-sideband frequency-agile pump pulse train (DSFA-PPT), and the continuous probe wave is up-shifted by a fixed frequency value. With the frequency-scanning of DSFA-PPT, pump pulses at the -1st-order sideband and the +1st-order sideband interact with the continuous probe wave via stimulated Brillouin scattering, respectively.

Quasi-acoustic impedance matching distributed opto-mechanical sensor with aluminized coating optical fibers.

The uncoated single-mode fiber has been extensively researched as an opto-mechanical sensor since it can achieve substance identification of the surrounding media by exciting and detecting transverse acoustic waves via forward stimulated Brillouin scattering (FSBS), but it has the danger of being easily broken. Although polyimide-coated fibers are reported to allow transverse acoustic waves transmission through the coating to reach the ambient while maintaining the mechanical properties of the fiber, it still suffers from the problems of hygroscopic property and spectral instability. Here, we propose a distributed FSBS-based opto-mechanical sensor using an aluminized coating optical fiber.

OPGW positioning and early warning method based on a Brillouin distributed optical fiber sensor and machine learning.

A method of optical fiber composite overhead ground wire (OPGW) positioning based on a Brillouin distributed optical fiber sensor and machine learning is proposed. A distributed Brillouin optical time-domain reflectometry (BOTDR) and Brillouin optical time-domain analyzer (BOTDA) are designed, where the ranges of BOTDR and the BOTDA are 110 km and 125 km, respectively. An unsupervised machine learning method density-based spatial clustering of applications with noise (DBSCAN) is proposed to automatically identify the splicing point based on the Brillouin frequency shift (BFS) difference of adjacent sections.

Enhanced chirality in a dielectric metasurface without breaking symmetry.

We propose a dielectric metasurface constructed by quadrumer silicon nano-disks with crossed slots in the middle. This metasurface can support the excitation of bound states in the continuum which are closely related to the toroidal dipole resonance. After introducing chiral enantiomers with weak chirality into the surrounding medium, due to the bound states in the continuum, the chiroptical effect of the metasurface can be greatly enhanced.

Ring-core few-mode fiber and DPP-BOTDA-based distributed large-curvature sensing eligible for shape reconstruction.

This study proposes a distributed large-curvature sensor based on ring-core few-mode fiber (RC-FMF) and differential pulse-pair Brillouin optical time-domain analysis (DPP-BOTDA). The RC-FMF is adhered to a thin steel substrate and an asymmetric hump shape is reconstructed using the Frenet-Serret algorithm. The proposed curvature sensor demonstrates a larger curvature-sensing range, excellent tolerance to bending-induced optical loss, and increased Brillouin gain coefficient.

Facilitating Uniform Large-Scale MoS, WS Monolayers, and Their Heterostructures through van der Waals Epitaxy.

The fabrication process for the uniform large-scale MoS, WS transition-metal dichalcogenides (TMDCs) monolayers, and their heterostructures has been developed by van der Waals epitaxy (VdWE) through the reaction of MoCl or WCl precursors and the reactive gas HS to form MoS or WS monolayers, respectively. The heterostructures of MoS/WS or WS/MoS can be easily achieved by changing the precursor from WCl to MoCl once the WS monolayer has been fabricated or switching the precursor from MoCl to WCl after the MoS monolayer has been deposited on the substrate. These VdWE-grown MoS, WS monolayers, and their heterostructures have been successfully deposited on Si wafers with 300 nm SiO coating (300 nm SiO/Si), quartz glass, fused silica, and sapphire substrates using the protocol that we have developed.

Brillouin dynamic grating erasure technique for fast all-optical signal processing.

Brillouin dynamic grating (BDG) is an attractive storage unit for all-optical signal storage and processing. However, the processing speed of the traditional "write-read" scheme is severely limited by the inter-process interference (IPI) due to the residual BDG. Here, we propose an all-optical "write-read-erase" scheme to avoid the IPI effect, which can effectively eliminate the residual BDG through an erase pulse.

Distributed Airflow Sensing Based on High-Spatial-Resolution BOTDA and a Self-Heated High-Attenuation Fiber.

An all-fiber distributed airflow sensing method based on a differential pulse-width pair Brillouin optical time domain analysis (DPP-BOTDA) and a self-heated high-attenuation fiber (HAF) is proposed and demonstrated. The HAF heated the sensing fiber, producing a gradient temperature distribution in it through physical contact, where the temperature distribution was obtained by DPP-BOTDA with a spatial resolution of 5 cm. The heat loss caused by the airflow was reflected in the decrease in the Brillouin frequency shift and spatially resolved by DPP-BOTDA.

Light people: Professor Perry Shum spoke about fiber-enabled industries.

Fiber technologies have fundamentally reshaped the way we see, the way we sense, the way we communicate, and the way we live. They were so well developed that in some industries such as telecommunication, they were even taken for granted. For that, Light: Science & Applications invited Professor Perry Shum, a pioneer in fiber technologies and their industrialization, to speak about what chances fiber technologies can bring to industries.

Multipoint dispersion spectroscopic gas sensing by optical FMCW interferometry.

We present a novel, to the best of our knowledge, multipoint gas-sensing method based on dispersion spectroscopy using optical frequency-modulated continuous-wave (FMCW) techniques. By taking advantage of the optical FMCW's excellent multiplexing capability with high spatial resolution, the phase noise in the retrieved dispersion signal is efficiently suppressed. As a proof of concept, this method is experimentally demonstrated with three acetylene gas-sensing nodes, achieving a sensitivity of 30 ppm, a sensing spatial resolution of 30 cm, and a linear dynamic range of more than 3 orders of magnitude.

Polarization separation assisted optomechanical time-domain analysis with submeter resolution.

Optomechanical time-domain analysis (OMTDA) is a novel approach to measure distributed acoustic impedance of surrounding media with a high spatial resolution based on coherent forward stimulated Brillouin scattering probing. However, the spatial resolution is still limited by the polarization noise and influence of activation pulse. In this Letter, we propose a polarization separation based OMTDA to further improve the resolution.