We developed a distributed vibration sensor by using heterodyne detection and signal processing of moving averaging differential for the phase optical time domain reflectometry system. The broadband acoustic frequency components generated pencil-break have been measured identified in location our first time. Pencil break measurement is standard technique to emulate emission cracks concrete or steel bridges early crack identification. spatial resolution 5m highest response 1 kHz, which...

Brillouin scattering in optical fiber describes the interaction of an electro-magnetic field (photon) with a characteristic density variation fiber. When electric amplitude beam (so-called pump wave), and another wave is introduced at downshifted frequency (namely Stokes beating between waves creates modified change via electrostriction effect, resulting so-called stimulated scattering. The associated mechanical acoustic wave; it may be affected by local temperature, strain, vibration which...

A differential pulse-width pair Brillouin optical time domain analysis (DPP-BOTDA) for centimeter spatial resolution sensing using meter equivalent pulses is proposed. This scheme uses the waveform subtraction at same scanned frequency obtained from pulse lights with different pulse-widths (e.g. 50ns and 49ns) to form gain spectrum (BGS) each fiber location. The defined by average of rise fall length a small stress section rather than difference length. 0.18m 50/49ns 0.15m 20/19ns over 1km...

Abstract Inspired by biological systems, trainable responsive materials have received burgeoning research interests for future adaptive and intelligent material systems. However, the to date typically cannot perform active work, training allows only one direction of functionality change. Here, we demonstrate thermally hydrogel systems consisting two thermoresponsive polymers, where volumetric response system upon phase transitions enhances or decreases through a process above certain...

Abstract Biological tissues, such as tendons or cartilage, possess high strength and toughness with very low plastic deformations. In contrast, current strategies to prepare tough hydrogels commonly utilize energy dissipation mechanisms based on physical bonds that lead irreversible large deformations, thus limiting their load‐bearing applications. This article reports a strategy toughen using fibrillar connected double networks (fc‐DN), which consist of two distinct but chemically...

A system based on all-polarization-maintaining configurations of the phase-sensitive optical time-domain reflectometry (OTDR) is presented for vibration sensing. Both polarization-induced signal fading and noise are mitigated via polarization-maintaining components. The detectable frequency response increased to ~2.25 kHz. Moreover, only a straight sensing fiber segment ~0.13 m instead several closed loops needed sense event with spatial resolution 1 m, which makes it convenient monitoring...

We report a high-spatial-resolution and long-range distributed temperature sensor through optimizing differential pulse-width pair Brillouin optical time-domain analysis (DPP-BOTDA). In DPP-BOTDA, the signal suffers from signal-to-noise ratio (SNR) reduction with respect to original signals, for fixed difference SNR increases pulse width. Through reducing width transient regime (near or less than phonon lifetime) decrease after process, optimized 8/8.2 ns is applied realize 2 cm spatial...

A novel approach to realize long-range distributed temperature and strain measurement with high spatial resolution, as well is proposed based on optical frequency-domain reflectometry (OFDR). To maintain the resolution accuracy while increasing sensing length, an optimized nonlinearity compensation algorithm implemented ensure a large wavelength tuning range. The compensated OFDR trace exhibits improved at short distance, gradually deteriorates far end due accumulated phase noise induced by...

The distributed vibration or dynamic strain information can be obtained using time-resolved optical frequency-domain reflectometry. Time-domain is resolved by measuring Rayleigh backscatter spectrum in different wavelength ranges which fall successive time sequence due to the linear sweep of tunable laser source with a constant sweeping rate. local shift vibrated state respect that non-vibrated used determine at specific position along fiber length. Standard single-mode fibers as sensing...

We propose and demonstrate a high-performance long-range Brillouin optical time-domain analysis (BOTDA) based on time-division multiplexing measurement, where probe pulse pump are used to perform the measurement selected sensing section, of entire fiber is realized by combining series measurements over different sections through changing delay time between two pulses. In experiment, 100 km divided into 11 gain-controlled principle, spatial resolutions 0.6 m 2 obtained at end 75 km, respectively.

We demonstrate a high-performance Brillouin optical time-domain analysis (BOTDA) system with an extended sensing range by combining frequency-division multiplexing and in-line Erbium doped fiber amplifiers (EDFAs). The BOTDA features multiple sections of fibers different frequency shifts, it reduces the effective interaction length to one resonant section rather than entire fiber, so that power CW probe can be increased enhance signal within individual consequently extend combined high...

Distributed acoustic sensors provide a powerful instrumentation for ultrasound testing to identify the internal crack and deformation with location assessing structural conditions predicting potential failure. This paper provides tutorial review of milestones leading development distributed sensor based on Rayleigh back scattering. It offers discussion basic principles, optical configurations system design requirement, various detection schemes, performance limitations applications maximum...

Statistical characteristics of location related intensity distribution in phase-sensitive optical time-domain reflectometry ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Phi $ </tex-math></inline-formula> -OTDR) are theoretically analyzed and experimentally demonstrated. The polarization diversity scheme is adopted into the -OTDR with a coherent detection to effectively mitigate fading effect. A real...

Guided acoustic wave Brillouin scattering has gained considerable interest in recent years because of its capacity to detect mechanical features materials surrounding the optical fiber. Nevertheless, distributed measurements using this mechanism are rarely taken impracticality method’s forward mechanism. Recently, remarkable work ingenious schemes managed address difficulty, which opens a brand new way achieve position-resolved substance identification. However, due long lifetime and...

Shape-changing polymeric materials have gained significant attention in the field of bioinspired soft robotics. However, challenges remain versatilizing shape-morphing process to suit different tasks and environments, designing systems that combine reversible actuation self-healing ability. Here, we report halogen-bonded liquid crystal elastomers (LCEs) can be arbitrarily shape-programmed self-heal under mild thermal or photothermal stimulation. We incorporate halogen-bond-donating...

Dielectric capacitors are widely used in advanced electrical and electronic systems due to the rapid charge/discharge rates high power density. High comprehensive energy storage properties ultimate ambition field of application achievements. Here, high-entropy strategy is proposed design fabricate single-phase homogeneous (Bi

We report on what we believe to be the first truly distributed birefringence measurement of polarization-maintaining fibers (PMFs) based transient Brillouin grating (TBG). A TBG is created by two short pump pulses in slow axis PMF, and then birefringence-related spectrum mapped scanning a probe pulse launched fast axis, where local can calculated using induced frequency shift. Two types widely used PMFs, bow-tie panda, with length 8 m were measured at spatial resolution 20 cm, results show...

Coded optical probe pulses in return-to-zero/non-return-to-zero (RZ/NRZ) formats are used for long-range distance sensing based on a differential pulse-width pair Brillouin time-domain analysis (DPP-BOTDA) order to enhance the spatial resolution and measurement accuracy. It is found that using RZ format maintains spectral shape, enhances range leads higher signal-to-noise ratio compared single-pulse analysis. With 512 bit RZ-coded pulse pairs of 60/55 ns DPP-BOTDA, approximately 0.5 m strain...

We report on a high-spatial-resolution simultaneous strain and temperature measurement in time domain through measuring Brillouin frequency shift (BFS) birefringence-induced (BireFS) polarization-maintaining fiber. High-spatial-resolution BFS BireFS are obtained differential pulsewidth pair optical time-domain analysis local grating, respectively. Simultaneous with spatial resolution of 20 cm is demonstrated 6-m Panda The accuracy 0.4°C 9 με, their range can be up to 700°C 14 mε,

A distributed optical fiber sensor with the capability of simultaneously measuring temperature and strain is proposed using a large effective area non-zero dispersion shifted (LEAF) sub-meter spatial resolution. The Brillouin frequency shift measured time-domain analysis (BOTDA) differential pulse-width pair technique, while spectrum Rayleigh backscatter frequency-domain reflectometry (OFDR). These shifts are functions both strain, can be used as two independent parameters for discrimination...

Abstract Designing hollow micro/nano structures for gas sensing materials is highly desirable boosting properties and still remains challenging, especially through a simple economic way. Herein, porous In 2 O 3 nanorod (In ‐HNR), which was successfully fabricated by thermal decomposition of an In–MOF (CPP‐3) precursor, applied as materials. The pristine CPP‐3 obtained ‐HNR were systematically characterized various techniques, such XRD, SEM, TEM, TGA‐DTA, XPS, Raman N physisorption....

Microstructures is an international peer-reviewed, open access, online journal. The journal of publishes articles covering new research and developments, perspectives, reviews related to the microstructures materials, including, but not limited metals alloys, ceramics, polymers, composites, crystals, glasses, biomaterials, interfaces nanomaterials.

A novel fiber-optic refractometer is proposed and demonstrated to achieve temperature- axial strain-compensated refractive index measurement using highly sensitive outer-cladding modes in a tapered bend-insensitive fiber based Mach-Zehnder interferometer. Peak wavelength shifts associated with different spatial frequency peaks are calibrated obtain wavelength-related character matrix (λ)M(RI,T,ε) for simultaneous of multiple environmental variables. phase-related (Φ)M(RI,T,ε) also acquired...

We propose and demonstrate an ultrahigh-resolution optical spectrometry based on Brillouin dynamic gratings (BDGs). Taking advantage of creating a long grating in fiber, ultra-narrow bandwidth filter is realized by operating BDG single-mode fiber (SMF), the performed sweeping center wavelength BDG-based through swept-tuned laser. The features ultrahigh resolution, large coverage, simple direction-detection scheme. In experiment, 4 fm (0.5 MHz) spectral resolution achieved 400 m SMF, coverage...