Dual Regime Mode-Locked and Q-Switched Erbium-Doped Fiber Laser by Employing Graphene Filament-Chitin Film-Based Passive Saturable Absorber.

We investigate the dynamics of high energy dual regime unidirectional Erbium-doped fiber laser in ring cavity, which is passively Q-switched and mode-locked through the use of an environmentally friendly graphene filament-chitin film-based saturable absorber. The graphene-chitin passive saturable absorber allows the option for different operating regimes of the laser by simple adjustment of the input pump power, yielding, simultaneously, highly stable and high energy Q-switched pulses at 82.08 nJ and 1.

Three-dimensional force-tactile sensors based on embedded fiber Bragg gratings in anisotropic materials.

Three-dimensional force-tactile sensors have attracted much attention for their great potential in the applications of human-computer interaction and bionic intelligent robotics. Herein, a flexible haptic sensor based on dual fiber Bragg gratings (FBGs) embedded in a bionic anisotropic material is proposed for the detection of 3D forces. To achieve the discrimination of normal and tangential force angles and magnitudes, FBGs were orthogonally embedded in a flexible silicone cylinder for force determination.

Compact Harmonic Vernier Sensor Based on an In-Fiber FPI with Three Reflector System for Simultaneous Gas Pressure and Temperature Measurement.

In this work, we proposed a sensitivity-enhanced temperature sensor, a compact harmonic Vernier sensor based on an in-fiber Fabry-Perot Interferometer (FPI), with three reflective interfaces for the measurement of gas temperature and pressure. FPI consists of air and silica cavities formulated by single-mode optical fiber (SMF) and several short hollow core fiber segments. One of the cavity lengths is deliberately made larger to excite several harmonics of the Vernier effect that have different sensitivity magnifications to the gas pressure and temperature.

Development of polarization modulator using MXene thin film.

In this work, polarization modulator utilizing MXene material, namely NbC is demonstrated. S band signal is injected into NbC thin film and is modulated by 1400 nm laser diode. A total of 39.

Generation of mode-locked pulses based on D-shaped fiber with CdTe as a saturable absorber in the C-band region.

This study demonstrates the potential of cadmium telluride (CdTe), a part of the quantum dot (QD) family, as a saturable absorber (SA) to generate ultrashort pulses at the C-band region. The SA was fabricated by drop-casting the CdTe material onto the exposed core of the D-shaped fiber. The nonlinear property of the fabricated SA has a modulation depth of 1.

Polarization response of planarized optical waveguides to determine the anisotropic complex refractive index of graphene oxide thin films.

The polarization response of graphene oxide (GO)-coated planarized optical waveguides is used to determine the complex refractive index of GO film. GO films with thicknesses between 0.10 and 0.

Fabrication of a carbon nanotube/tungsten disulfide visible spectrum photodetector.

Two-dimensional-material-based photodetectors are gaining prominence in optoelectronic applications, but there are certain factors to consider with bulk material usage. The demand for a highly responsive and highly efficient device with an inexpensive fabrication method is always of paramount importance. Carbon nanotubes (CNT) are well known, owing to their upheld vigorous structural and optoelectronic characteristics, but to fabricate them at a large scale involves multifarious processes.

Laser-heated needle for biopsy tract ablation: In vivo study of rabbit liver biopsy.

Purpose: To investigate the efficacy of a newly-developed laser-heated core biopsy needle in the thermal ablation of biopsy tract to reduce hemorrhage after biopsy using in vivo rabbit's liver model.

Materials And Methods: Five male New Zealand White rabbits weighed between 1.5 and 4.

Cascaded Fabry-Perot interferometer-regenerated fiber Bragg grating structure for temperature-strain measurement under extreme temperature conditions.

We demonstrated an optical fiber sensor based on a cascaded fiber Fabry-Perot interferometer (FPI)-regenerated fiber Bragg grating (RFBG) for simultaneous measurement of temperature and strain under high temperature environments. The FPI is manufactured from a ∼74 µm long hollow core silica tube (HCST) sandwiched between two single mode fibers (SMFs). The RFBG is inscribed in one of the SMF arms which is embedded inside an alundum tube, making it insensitive to the applied strain on the entire fiber sensor, just in case the temperature and strain recovery process are described using the strain-free RFBG instead of a characteristic due-parameter matrix.

56 nm Wide-Band Tunable Q-Switched Erbium Doped Fiber Laser with Tungsten Ditelluride (WTe) Saturable Absorber.

A wide-band and tunable Q-switched erbium-doped fiber (EDF) laser operating at 1560.5 nm with a tungsten ditelluride (WTe) saturable absorber (SA) is demonstrated. The semi-metallic nature of WTe as well as its small band gap and excellent nonlinear optical properties make it an excellent SA material.

Reduced Graphene Oxide-Silver Nanoparticles for Optical Pulse Generation in Ytterbium- and Erbium-Doped Fiber Lasers.

This work has demonstrated the potential of a reduced graphene oxide silver/polyvinyl alcohol (rGO-Ag/PVA) film as a saturable absorber (SA) in ytterbium and erbium based Q-switched optical fiber lasers. The facile hydrothermal method was used to synthesize the nanocomposite between rGO and Ag nanoparticles. This was followed by a simple solution method to form the rGO-Ag film using PVA as the host polymer.

Nanosecond pulse laser generation at 1.55 and 2 μm regions by integrating a piece of newly developed chromium-doped fiber-based saturable absorber.

This paper demonstrated the nanosecond pulse laser operation at 1.55 and 2 μm wavelength regions using a newly develop chromium-doped fiber (CrDF) as a saturable absorber (SA) to convert efficiently continuous-wave laser operation to nanosecond pulse laser operation. The laser uses an erbium-doped fiber (EDF) and thulium-doped fiber as the gain medium.

1.3 μm fiber grating in a thin-core fiber for LP-LP mode converters and sensing ability.

We demonstrate an all-fiber structure that can realize LP-LP mode conversion and twist measurement. It is a thin-core fiber (TCF) grating at a wavelength of 1310 nm cascaded to a short segment of a TCF of a different core size. It is found that the different core size of the TCF between the fiber and the grating has an impact on the excitation of a higher-order mode and mode conversion efficiency.

Tungsten-disulphide-based heterojunction photodetector.

Two-dimensional (2D) materials have realized significant new applications in photonics, electronics, and optoelectronics. Among these materials is tungsten disulphide (WS), which is a 2D material that shows excellent optoelectronic properties, tunable/sizable bandgap in the visible range, and good absorption. A polycrystalline WS thin film is successfully deposited on a substrate using radio frequency magnetron sputtering at room temperature.

Regenerated grating produced in a multimaterial glass-based photosensitive fiber with an ultrahigh thermal regeneration ratio.

This work demonstrates thermal regeneration of gratings inscribed in a new type of multi-material glass-based photosensitive fiber. And isothermal annealing procedure has been carried out on a type-I seed grating (SG) imprinted in erbium-doped zirconia-yttria-alumina-germanium (Er-ZYAG) silica glass-based fiber, which is initiated from room temperature of 25°C up to 900°C. The findings show that the created regenerated grating (RG) has an ultrahigh thermal regeneration ratio with a value of 0.

A Recent Progress of Steel Bar Corrosion Diagnostic Techniques in RC Structures.

Corrosion of steel bar is one of key factors undermining reinforced concrete (RC) structures in a harsh environment. This paper attempts to review the non-destructive procedures from the aspect of the corrosion measurement techniques, especially their advantages and limitations. Systematical classification of diagnostic methods is carried out to determine any probable corrosion issues before the structures become severe, and helps choose the suitable method according to different construction features.

Effect of two annealing processes on the thermal regeneration of fiber Bragg gratings in hydrogenated standard optical fibers.

In this work, we demonstrate the thermal regeneration of fiber Bragg gratings written in the hydrogenated standard communication optical fibers by two annealing processes. The first annealing process is done at an intermediate temperature (500°C, 700°C, and 900°C) for a specific period of time before cooling down to room temperature. The second annealing is at 1000°C in which the thermal regeneration is attained.

Chitosan capped nickel oxide nanoparticles as a saturable absorber in a tunable passively Q-switched erbium doped fiber laser.

Nickel oxide (NiO) nanoparticles successfully prepared from a nickel(ii) chloride hexahydrate precursor are used to form a chitosan capped NiO nanoparticle thin film to serve as a saturable absorber (SA) for the generation of passively Q-switched pulses in an erbium doped fiber laser (EDFL). The NiO/chitosan SA based EDFL is able to generate stable pulsed outputs at a low threshold pump power of 104.90 mW with a central wavelength at 1562 nm.

Temperature-independent hygrometry using micromachined photonic crystal fiber.

An in-fiber Mach-Zehnder interferometer (MZI) is proposed and experimentally demonstrated for relative humidity (RH) and temperature measurements. The MZI is formed by a grapefruit-shaped photonic crystal fiber (G-PCF) cascaded with a short section of multimode fiber that serves as a mode coupler. To enhance sensitivity to humidity, femtosecond laser micromachining was performed to remove a portion of cladding of the G-PCF to expose its core to the ambient medium.

Mach-Zehnder interferometric magnetic field sensor based on a photonic crystal fiber and magnetic fluid.

A Mach-Zehnder interferometric magnetic field sensor based on a photonic crystal fiber (PCF) and magnetic fluid (MF) was designed and experimentally demonstrated. The sensing probe consists of a single-mode-(SM)-multimode-PCF-SM fiber structure through arc fusion splicing. It was then laser engrave notched with the femtosecond laser so that the PCF cladding was selectively infilled MF.

Strain measurement at temperatures up to 800°C using regenerated gratings produced in the highGe-doped and B/Ge co-doped fibers.

In this work, we have proposed a sensor for strain measurement in high-temperature environments up to 800°C by employing two regenerated fiber Bragg gratings. Two seed gratings (SGs) are inscribed in high Ge-doped and B/Ge-codoped fibers, respectively, which possess different temperature sensitivities. To achieve two gratings with different strain sensitivities, one of the gratings is chemically etched to reduce the fiber diameter for strain sensitivity enhancement.

Temperature sensing using CdSe quantum dot doped poly(methyl methacrylate) microfiber.

This work describes noncontact temperature measurements using wavelength shifts of CdSe quantum dot (QD) doped poly(methyl methacrylate) microfiber. The sensor is fabricated using a drawing method by bridging two tapered single mode fibers with a polymer microfiber (PMF) approximately 3 μm in diameter. A set of a PMF section with and without the doping of the CdSe-ZnS core-shell QD was applied as sensing probes and used to measure temperatures over the range of 25°C-48°C.

Curvature and Temperature Measurement Based on a Few-Mode PCF Formed M-Z-I and an Embedded FBG.

We have experimentally demonstrated an optical fiber Mach-Zehnder interferometer (MZI) structure formed by a few-mode photonic crystal fiber (PCF) for curvature measurement and inscribed a fiber Bragg grating (FBG) in the PCF for the purpose of simultaneously measuring temperature. The structure consists of a PCF sandwiched between two multi-mode fibers (MMFs). Bending experimental results show that the proposed sensor has a sensitivity of -1.

Investigation on the Effects of the Formation of a Silver "Flower-Like Structure" on Graphene.

In this report, we experimentally investigate the formation of "flower-like silver structures" on graphene. Using an electrochemical deposition technique with deposition times of 2.5 and 5 min, agglomerations of silver nanoparticles (AgNPs) were deposited on the graphene surfaces, causing the formation of "flower-like structures" on the graphene substrate.

Potassium permanganate (KMnO) sensing based on microfiber sensors.

Two straight microfiber sensors are proposed and demonstrated for the detection of various concentrations of a potassium permanganate (KMnO) solution. Two types of straight microfibers, namely, silica microfiber and poly(methyl methacrylate) microfiber, have been fabricated by using the flame brushing technique and the direct drawing technique, respectively. Based on the varied KMnO concentrations of the solution from 1% to 6%, the measurement of the peak voltage of the transmission power was made.