Abstract Laser spectroscopy outperforms electrochemical and semiconductor gas sensors in selectivity environmental survivability. However, the performance of state-of-the-art laser is still insufficient for many high precision applications. Here, we report mode-phase-difference photothermal with a dual-mode anti-resonant hollow-core optical fiber demonstrate all-fiber (acetylene) detection down to ppt (parts-per-trillion) <1% instability over period 3 hours. An could be designed transmit...

Photoacoustic spectroscopy, a powerful tool for gas analysis, typically uses bulky cells and discrete microphones. Here we exploit light-gas-acoustic interaction in gas-filled anti-resonant hollow-core-fiber (AR-HCF) to demonstrate photoacoustic Brillouin spectroscopy (PABS). Pump absorption of molecules excites the acoustic resonances fiber, which modulates phase probe beam propagating fiber. Detection modulation enables spectroscopic characterization species concentration as well fiber...

We report broadband all-fiber optical phase modulation based on the photo-thermal effect in a gas-filled hollow-core fiber. The dynamics are studied by multi-physics simulation. A modulator is fabricated using 5.6-cm-long anti-resonant fiber with pure acetylene filling. It has half-wave power of 289 mW at 100 kHz and an average insertion loss 0.6 dB over broad wavelength range from 1450 to 1650 nm. rise fall time constants 3.5 3.7 μs, respectively, 2–3 orders magnitude better than previously...

The increasing importance of hydrogen as an energy carrier and industrial material calls for sensors with higher sensitivity, better selectivity, faster response, wider dynamic range.Here, we report a nanofiber (NF) sensor that satisfies these requirements single sensing element.The is based on stimulated Raman scattering spectroscopy, but the tightly confined evanescent field associated NF enhances gain per unit length by factor 30 to 10 2 over state-of-the-art hollow-core photonic crystal...

Abstract With micro- and nano-structured optical fibers, parts-per-million to parts-per-trillion level gas detection has been demonstrated for a range of gases such as methane, acetylene, ethane, carbon monoxide, hydrogen, oxygen. We review the recent development in fiber cells systems based on direct absorption, photothermal, photoacoustic, stimulated Raman spectroscopies.

A temperature-controlled electrochemical sensor was constructed based on a composite membrane composed of temperature-sensitive polymer poly (N-isopropylacrylamide) (PNIPAM) and carboxylated multi-walled carbon nanotubes (MWCNTs-COOH). The has good temperature sensitivity reversibility in detecting Dopamine (DA). At low temperatures, the is stretched to bury electrically active sites nanocomposites. cannot exchange electrons through polymer, representing an "OFF" state. On contrary,...

We present an all-fiber intracavity photothermal (IC-PT) spectroscopic gas sensor with a hollow-core photonic bandgap fiber (HC-PBF) cell. The cell is placed inside fiber-ring laser cavity to achieve higher light intensity in the hollow core and hence PT modulation signal. An experiment 0.62-m-long HC-PBF demonstrated noise equivalent concentration of 176 ppb acetylene. Theoretical modeling shows that IC-PT has potential achieving sub-ppb (parts-per-billion) acetylene detection sensitivity.

La 0.67 Ca 0.33 Mn O 3 − δ ∕ Nb – Sr Ti p-n junction was fabricated by pulsed laser deposition. The I-V curves of this show rectifying behavior. Negative differential resistance (NDR) observed at low temperatures under large bias voltages and NDR becomes more remarkable with decreasing temperature. In addition to NDR, the also hysteresis. results were explained in terms effect local Joule heating on phase separation strained ultrathin La0.67Ca0.33MnO3−δ thin film.

Hydrogen detection is of great importance in chemical and energy industries. Optical fiber hydrogen sensors show flexibility compactness, have the potential for distributed analysis. However, traditional encounter a challenge with light interacting directly because only displays weak quadrupole absorption, metallic palladium platinum thin-film coatings are typically used as an optically detectable label. Here, based on stimulated Raman spectroscopy hollow-core photonic crystal fibers, we...

This article investigated the effect of cellulose microcrystal (CMC) and low molecular polyamide (PA650) on mechanical water absorption properties ramie fiber‐reinforced epoxy composites. Results showed that coating mixture CMC PA650 (CMC/PA650) surface fiber improved interfacial adhesion strength fiber/epoxy As a result, flexural strength, modulus, interlaminar shear PA650/CMC‐coated fabric‐reinforced composites (CPRFC) were 10.6%, 8.1%, 7.4% higher than those fabric without reinforced...

Asymmetric I-V behaviors induced by large currents in La0.82Ca0.18MnO3 (LCMO) films are studied. The contribution of LCMO to the asymmetric is demonstrated eliminating LCMO/electrode interface. can be tuned negative voltage pulse and positive current excitations between two resistive states. A band bending model based on local oxygen electromigration at grain boundaries proposed account for results. This work helpful understanding mechanism effect manganites also its applications.

Background: A simple and effective method to separate chlorogenic acid from Eucommia ulmoides leaves with macroporous resin was studied in this paper. Methods: In order optimize the separation process of leaves, dynamic adsorption desorption experiments were carried out on a glass column filled XDA-8 resin. Based First-principles calculation, possible models simulated. Results: Among six resins, showed good adsorption/desorption capacity high ratio for acid. After being treated once, content...

We present the first experimental demonstration of distributed hydrogen sensing using stimulated Raman scattering in gas-filled hollow-core photonic crystal fibers. The system performances terms sensitivity, selectivity, dynamic range and distance are discussed.

We report an oxygen sensor based on laser photothermal spectroscopy in a hollow-core fiber with double transmission (i.e., visible and near infrared) bands. With 4.3-cm-long hollow- core as the gas cell, we demonstrated detection down to 1800 ppm.

A novel technique based on stimulated Raman gain spectroscopy with an optical nano-taper is demonstrated. With a 600-nm-diameter and 15-mm-long silica nano-taper, hydrogen detection down to 170 parts-per-million response time of <10 s achieved.

Photoacoustic spectroscopy is demonstrated with gas filled microstructured hollow core optical fibers. This technique may be used for high sensitivity sensing, non-invasive fiber characterization, and fiber-optic phase modulation devices.

We report mode-phase-difference photothermal spectroscopy with a dual-mode anti-resonant hollow-core fiber. Ultra-sensitive gas detection down to ppt level is demonstrated good stability and unprecedented dynamic range of over 7 orders magnitude.