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The sol-gel process has been applied to cotton fabrics to cover the fibers with a silica-based film, which can improve their thermal oxidation and combustion behaviors. Silica sol, silane coupling agent 3-glycidoxypropyltrimethoxysilane (KH560) and flame retardant zinc borate (ZB) are used together to prepare SiO2-KH560-ZB hybrid sol, which is then finished on the surface of cotton fabric through impregnation and baking. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), limiting oxygen index analysis (LOI) and microscale combustion calorimetry (MCC) are used to characterize functional groups, thermal stability and flammability properties of finished fabrics. Surface morphology of sol modified cotton fabrics are analyzed by scanning electron microscopy (SEM) and energy dispersive X-Ray spectroscopy (EDX). Results show the sols are successfully converted into gel coatings onto cotton fabrics, and continuous smoldering phenomenon of resulted fabrics disappears. ΔLOI/Δm of SiO2-KH560-ZB coated cotton fabric reaches the highest of 0.37%/g, char residue rate is as high as 28.43% and the peak heat release rate (PHRR) is reduced by 26.9% (83.7 W/g). KH560 has a significant coupling effect on combining components in the sol system and increases compatibility between sols and cotton fabrics. ZB (cooling, separation, dilution and suppression), silica sol (physical barrier) and KH560 show excellent synergistic effects in enhancing overall flame retardancy.

By thermogravimetry (TG) experiments, evolution behaviors and properties of thermal oxidation processes at low temperature (< 230.0 °C) of a bituminous coal with five moisture contents were investi...

The surface resonance scattering of silver nanoparticles, commonly used to enhance the matrix of the Raman, is the most active of all metal nano particles which can greatly improve the sensitivity of the detected molecules. At the same time, the sterilization ability of silver is also highly recommended in the field of biology. In this study, cytosine nucleoside was used as a template to quickly synthesize silver-based composite nanomaterials (Ag–C/Au) with enhanced fluorescence and good water solubility. Then, the fluorescence spectrum, lifetime, the ultraviolet-visible absorption spectrum of the material, and the size and shape of the grain size were studied through characterization. After that, the interaction between the silver-based composite nanomaterial Ag–C/Au and the recombinant protein ephrin-b2 was studied by spectroscopy, and the mixed metalloprotein was used for electrocardiogram treatment of myocardial infarction in SD rats to establish a rat modeling, then the rats were grouped according to the different injections, and the heart rhythm variability (HRV) of different groups of rats with myocardial infarction (MI) was recorded. Finally, the program electrical stimulation (PES) was used to analyze the ventricular effective refractory period (VERP) and ventricular arrhythmia (VAs) in rats. In the experiment, Ag–C/Au nanomaterials produced strong yellow fluorescence under 370 nm ultraviolet excitation, with an approximate particle size of 1.6 nm; through spectral data fitting, it was found that the recombinant protein ephrin-b2 could be adsorbed on the surface of the composite nanomaterials, making the intensity of the characteristic peak decreased; the myocardial indicators of myocardial infarction rats based on ephrin- b2 + Ag–C/Au group were significantly improved, while the grouping of rats using Ag–C/Au alone didn't affect the electrophysiological characteristics after myocardial infarction, that is, ephrin-b2 could improve arrhythmia after myocardial infarction, and the improvement effect would be further strengthened when Ag–C/Au was added.

Recent studies suggested that the interactions between particles can induce aggregative nucleation and growth processes beyond those predicted by the traditional LaMer model of nanoparticle formation, but their nucleation and growth processes are still unclear. Here, we report a simple way to control the interaction between nanoparticles by manipulating the oleylamine (OAm) adsorbed on the surface of the nanoparticles. The size distributions of Ag nanoparticles produced at different reaction pressures were monitored as evidence for aggregative growth. From these kinetic data, the aggregative nucleation rate (Γ) of primary Ag nanoparticles under a 0.01 MPa was demonstrated to be faster than that under atmospheric pressure. This leads to a higher uniformity of Ag nanoparticles in a shorter time (10 min) than that achievable with previous methods. Furthermore, Ag nanoparticles supported on TiO2 exhibited a remarkable performance in the catalytic reduction of 4-nitrophenol (4-NP). After 4 min, 4-NP was completely reduced into 4-aminophenol (4-AP).

Summary Toward the preparation of industrial metal oxide catalysts, sacrificial organic templates, excessive solvents, complex impregnation, and drying steps are generally required. Here, we report a versatile rule for the simple synthesis of highly porous metal oxides with well-dispersed noble metal species. Porous metal oxides (Co3O4, FexOy, and Cr2O3) are obtained with some surface areas (e.g., Cr2O3: 224 m2·g−1) beyond the record value. Surprisingly, small noble metal nanoparticles (e.g., Pd: 3.1 and Pt: 3.2 nm) could be incorporated by this solid-state process simultaneously. Corresponding Rh-Co3O4, Pd-FexOy, and Pt-Cr2O3 exhibit excellent performance: CH4 combustion (T90 = ∼360°C and thermal stability: >100 h at 680°C), hydrogenation of nitrobenzene and derivatives (turnover number [TON] = 2.49 × 104, 300 mmol per run), and reversed water gas shift (RWGS) reaction (44% CO2 conversion with ∼98% CO selectivity and thermal stability: >100 h at 500°C), respectively. Therefore, current principle via a NaCl-based solid solution could provide a solid-state, fast, and efficient route for processing metal oxide catalysts.

Multi-walled carbon nanotube (MWCNT)/dextran/nano-gold composite was prepared by chemical solution reaction. The average diameter of gold nanoparticles was around 15 nm. MWCNT/dextran/nano-gold composites were uniformly dispersed in aqueous solution as electrode materials. MWCNT/dextran/nano-gold composites exhibited excellent electrochemical property in [Fe(CN)6]3– /4– solution. Experimental results showed that the MWCNT/dextran/nano-gold composites with 50% MWCNTs presented obvious redox peak and low impedance and had good electrochemical response to Cu2+. The redox peak currents were linear while the concentration of copper ions ranged from 1× 10–2 to 1 × 10–4 M. The relationship between oxidation peak currents I (A) and Cu2+ concentration C (M) was: ipk (A) = 2.6207 × 10–6 + 43.91572 × 10–4 × C (M), and the limit of determination (LOD) of Cu2+ was 0.63 × 10–6 M, and linear coefficient was 0.9923.

The sintering of Supported Transition Metal Catalysts (STMCs) is a core issue during high temperature catalysis. Perovskite oxides as host matrix for STMCs are proven to be sintering-resistance, leading to a family of self-regenerative materials. However, none other design principles for self-regenerative catalysts were put forward since 2002, which cannot satisfy diverse catalytic processes. Herein, inspired by the principle of high entropy-stabilized structure, a concept whether entropy driving force could promote the self-regeneration process is proposed. To verify it, a high entropy cubic Zr0.5(NiFeCuMnCo)0.5Ox is constructed as a host model, and interestingly in situ reversible exsolution-dissolution of supported metallic species are observed in multi redox cycles. Notably, in situ exsolved transition metals from high entropy Zr0.5(NiFeCuMnCo)0.5Ox support, whose entropic contribution (TΔSconfig = T⋆12.7 J mol−1 K−1) is predominant in ∆G, affording ultrahigh thermal stability in long-term CO2 hydrogenation (400 °C, >500 h). Current theory may inspire more STWCs with excellent sintering-resistance performance., Sintering of supported transition metal catalysts is problematic for high-temperature catalysis. Here the authors report entropy-driven, self-regeneration of high entropy oxide nanoparticles, promoting better stability and in situ reversible exsolution-dissolution process in multi-redox cycles.

Mesoporous iron oxides have shown excellent performance in many research areas such as catalysts, biosensors, enzyme immobilization, heavy metal adsorption, and drug delivery. The state-of-the-art synthesis methods are mostly wet chemistry processes. This paper reports a solvent-free approach for the rapid synthesis of mesoporous Fe 3 O 4 (specific surface area up to 170 m 2 /g) and Au@Fe 3 O 4 (highly dispersed Au nanoparticles, average particle size: ∼4 nm). With different amounts of added template agent, cetyltrimethylammonium bromide (CTAB), the pore structure could easily be adjusted. More importantly, the mesoporous Fe 3 O 4 exhibited good catalytic activity in carbon monoxide (CO) oxidation, outperforming commercially purchased Fe 3 O 4 with 100% CO conversion at around 274 °C vs. 490 °C for the commercial product.

By thermogravimetric (TG) experiments under 5 oxygen concentrations of 21.0, 40.0, 50.0, 60.0, 80.0% and 5 heating rates of 20.0, 30.0, 40.0, 50.0, 60.0 ℃/min, the combustion characteristics of jet coal and influences of oxygen concentrations and heating rates on them were investigated. Results show that the pyrolysis processes of jet coals consist of 3 segments of water evaporation, structure oxidation and mass-gaining, self-ignition and induced combustion and carbonization that lie in temperature ranges of 65.0~150.0 ℃, 150.0~290.0 ℃ and 290.0~650.0 ℃, respectively. Huainan jet coal samples burn more easily as universal ignition index increases. At constant heating rate, self-ignition temperature tends to decrease by 10.1~19.4 % with increasing oxygen concentration from 21.0 % to 80.0 %. However, the variation trend of oxidation process includes a slight rise when variation trend begins to fall. At constant oxygen concentration, the self-ignition temperature transformes into high temperature direction and lead to thermal lag effect. Values of Coal-oxidation time at various oxygen concentration levels decreased by 63.1~65.8 % at heating rates from 20.0 to 60.0 ℃/min. Accordingly, the coal-oxidation process is accelerated. A new index (R S ) named coal-oxidation difficulty level index to evaluate the lag effect of coal-oxidation process was proposed. Fitting results of three dimensionless parameters confirmed that the risk of spontaneous combustion determined by the coal-oxidation process still remains growing up although self-ignition temperature produces thermal lags with increasing heating rates.

By using sol-gel process, hybrid sols can be prepared and three dimensional nanoscale or nano-micro networks can be designed and formed onto bulk materials of diverse substrates (such as fabric and wood). Series of pure, composite and hybrid sols like SiO2, SiO2-KH560, SiO2-KH560-MA (Melamine), SiO2-KH560-BB (Boric Acid and Borax) and SiO2-KH560-TPP (Triphenyl Phosphate) including both nano-sols and traditional flame retardant components were prepared and used to finish cotton, polyester and polyester-cotton fabrics, particle size distributions and pH values of as-prepared sols were inspected. Limiting Oxygen Index (LOI), Thermogravimetry Analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR) experiments were conducted to determine flame retardancy, characterize pyrolysis properties and identify microstructural functional groups on the surfaces of sols-finished fabrics. Effectiveness, synergistic effects and function mechanisms of organically modified hybrid sols and flame retardants were explored. Results show that LOI values are all improved after modifications of cotton, polyester and polyester-cotton fabric, coverage of main pyrolysis stage have been extended to various degrees, and amounts of residual char increase exponentially. The flame retardant effects of cotton and polyester-cotton fabrics treated with SiO2-KH560-BB is most obvious. It shows that the flame retardant hybrid sols affect the pyrolysis courses and heat resistance capacities of fabrics have been improved. It is speculated the sols form coatings on surface of fabrics and inhibit further oxidation, decomposition, and melt dripping, prolong the main pyrolysis process, prevent the fabric further oxidation and decomposition, increase the char yield, improve the thermal stability of polyester fabric. For A3, a broad peak between 650~750cm-1 is seen, indicating that a large number of OH groups exist, and absorption peaks at 1295 cm-1 reveals the presence of Si-C-O groups. The OH groups, boric acid and borax can both strengthen dehydration and char formation capacities by developing thin films surrounding fibers. Superb synergistic effect happens.

Zinc oxide is a key material in catalysis. Designing of ZnO crystal aggregates with the surface defect has received significant attention. Herein, we synthesized ZnO aggregates with tiny primary nanoparticles through a mechanochemistry-assisted salt-templating (potassium chloride) method. Interestingly, this KCl-templating strategy could lead to significant increase in specific surface area (SSA) of ZnO (up to 91 m2/g), whereas commercial ZnO-COM has a SSA of 5 m2/g. Meanwhile, this strategy via ZnCl2-KCl solid solution has also created a number of oxygen vacancies into ZnO aggregates. With these attractive features, as-made Pd-ZnO catalyst showed outstanding performance in methanol steam reforming, especially at low temperature (20 % Conversion and 95 % CO2 Selectivity at 150 °C). Current strategy provides a gateway for the rational design of ZnO-based catalytic materials.

A new numerical model for simulating the propagation and quenching of a detonation wave in in-line flame arrester was developed by using FORTRAN language. Accordingly, this study analysed the initiating process, quenching rule of a detonation wave in an arrester element and effect of arrester structural parameters on the propagation process of a detonation wave. Results showed that the quenching length of detonation wave increases with porosity, and the two parameters present a quadratic function relationship. Quenching length minimally varied with the increase in arrester thickness. The detonation wave collided with the element wall whilst porosity decreased when detonation wave propagated in the arrester element. Consequently, a pressure peak drop of the detonation wave was observed. As arrester thickness increased, the pressure peak of the detonation wave in the arrester element and the value of temperature on the position where the transmitted shock wave lies decreased, thereby cause a strong inhibition to the detonation wave. Simulation result showed that detonation pressure decreased progressively as porosity increased, and the two parameters exhibited a quadratic function relationship. By contrast, detonation pressure increased progressively as arrester thickness grew, and the two parameters presented a quadratic function relationship.

Highly-ordered TiO2 nanotube arrays (TNTs) were prepared by anodisation in ethylene electrolytes containing 0.2–0.7 wt% NH4F. The dimension, chemical composition and optical characterisation of prepared TNTs were determined by the field-emission scanning electron microscopy, X-ray photoelectron spectroscopy and photoluminescence spectroscopy, respectively. Both the length and inner diameter of the prepared TNTs were increased with increasing NH4F concentration of electrolyte because of the faster electrochemical dissolution rate of TiO2. However, dimension of TNTs approached stable lengths and inner diameters as the NH4F concentration was higher than 0.3 wt%. The presence of Ti3+ state was observed for TNTs prepared with increasing NH4F concentration because of the charge compensation of the substitution of fluoride ions for oxygen ions. TNTs prepared in the electrolytes containing higher NH4F concentrations exhibited superior performance on the photocatalytic decomposition of Acid Red 4 possibly because more fluorides incorporated with TNTs to inhibit the recombination of electron–hole pairs.

Fiber reinforced composite materials were applied widely in aircraft and space vehicles engineering. Aimed to an advanced glass fiber reinforced composite material, a series of experiments for measuring thermal physical properties of this material were conducted, and the corresponding performance curves were obtained through statistic analyzing. The experimental results showed good consistency. And then the thermal physical parameters such as thermal expansion coefficient, engineering specific heat and sublimation heat were solved and calculated. This investigation provides an important foundation for the further research on the heat resistance and thermodynamic performance of this material.

Polyester materials were applied widely in aircraft and space vehicles engineering. Aimed to an advanced polyester material, a series of experiments for thermal physical properties of this material were conducted, and the corresponding performance curves were obtained through statistic analyzing. The experimental results showed good consistency. And then the thermal physical parameters such as thermal expansion coefficient, engineering specific heat and sublimation heat were solved and calculated. This investigation provides an important foundation for the further research on the heat resistance and thermodynamic performance of this material.

The phase-pure LiFePO4/C cathode materials have been successfully fabricated by precursor containing Fe2O3 coated with polyaniline through carbothermal reduction method. The polyaniline coating at Fe2O3 could restrict the growth of crystal and subsequently become electric carbon at higher synthesis temperature. Compared with conventional carbothermal reduction method, the sample showed a better capacity and less than 3% capacity fading after 30 cycles at various charge and discharge rate.

After reheated at different temperatures for 5 minutes, the 400MPa Ultrafine Grained Steel specimens were air-cooled to room temperature, and then carried out the mechanical nanocrystallization surface treatment and structure performance testing. On the basis of comparing the test results on the specimens before and after the mechanical nanocrystallization surface treatment, the process of mechanical nanocrystallization was analyzed briefly. The results show that: as the reheating temperature rising, the trend of grain size growing increases markedly, and the mechanical properties also drop down to different degrees; when the reheating temperature is around 800°C, because of the pearlite spheroidized significantly, its mechanical properties drop the most seriously; after the mechanical nanocrystallization surface treatment, not only its surface form a layer of fine nano-layer (about 100 nm) structure, but also its mechanical properties rise obviously, and the yield strength is over 450MPa.

Magnetic properties of Cu-doped LaMn1-xCuxO3 (x=0.05-0.30) systems are carefully studied in the temperature range of 2–300 K. A visible unexpected drop is observed in the ac susceptibility and the zero-field cooled dc magnetization curves for the dilute x ≤0.10 near 100K, which depends on the measuring frequency and magnetic field. Measurements on frequency dependence of ac susceptibility, observation of magnetic relaxation, and the existence of critical field indicate that the anomaly can be attributed to the domain wall pinning effects. This is directly proven by the results of ball milled nano-sized powder counterparts compared with the bulk materials.

Birefringence of a microstructure fibre with irregular structures is investigated using the finite element method. The birefringence of each sample is statistically analysed, and the relation between the birefringence and the irregular structure of the microstructure fibre is derived. The results indicate that the irregular structure of the symmetrical microstructure fibre result in the birefringence which is more strongly affected by disorder of air holes than the nonuniformity. Moreover, lower birefringence can be obtained with smaller air holes and larger pitch in the fibre structure.

Fibre Bragg gratings (FBGs) are inscribed in homemade microstructured fibres by the standard phase mask method. Enhanced couplings between the forward fundamental mode and backward cladding modes are obtained. The mode coupling and spectral characteristics are investigated experimentally. The cladding mode resonances can be affected by filling active materials into the air holes, which will be useful for the implementation of tunable photonic devices in optical fibre communication and sensing systems.

Enhancing coherent combining efficiency via choosing appropriate lasing wavelength in a Michelson compound cavity based on two 3?dB fibre loop mirrors and one fibre Bragg grating (FBG) has been experimentally demonstrated. The FBG with 4.5% reflectivity is replaced at the cleaved facet with 4% Fresnel reflection. A high coherent combining efficiency of 93.5% is obtained when the FBG with central wavelength at 1559.845?nm is introduced into the cavity, while it is only 90.1% combining efficiency with the FBG at central wavelength 1557.830?nm. In comparison with other reports, the proposed compound-cavity laser has the advantage of needless tuning FBG to obtain the coherent condition, and it is facile to ascertain the seemly wavelength lasing for a Michelson compound cavity.

Background Electrospinning is an easy and effective technique to produce submicron fibers possessing a range of attractive characteristics such as interconnected porous structures similar to natural ECM and good resilience to movement. Rapid and efficient cell attachment to nanofibrous matrices is a necessary prerequisite in tissue engineering. Thus, the aim of this study is to evaluate poly(ε-caprolactone-co-lactide)/Pluronic (PLCL/Pluronic) nanofibrous matrices with avidin-biotin technology for improving cell adhesion for the first time. Results PLCL/Pluronic nanofibers had relatively homogeneous fibers and interconnected porous structures. Pluronic significantly modified the hydrophilicity of nanofibrous matrices and PLCL/Pluronic nanofibrous matrices had better performance on maintaining cell proliferation. Avidin-biotin technology had no negative effect on the hydrophilic property, mechanical property and cell proliferation. Meanwhile, the attachment and spreading of adipose-derived stem cells (ADSCs) onto PLCL/Pluronic nanofibrous matrices with avidin-biotin technology was promoted obviously. Conclusions PLCL/Pluronic nanofibrous matrices inheriting the excellent characteristics of both PLCL and Pluronic have the better cell adhesion ability through avidin-biotin technology, implying a promising application in skin care, tissue regeneration and other related area.

A dual-wavelength laser system with wideband tunable wavelength spacing and more than 2 W output power is proposed and demonstrated. The operation principle of the laser system is based on the saturation gain characteristic of a cladding-pumped Er3+/Yb3+ co-doped fibre amplifier combining with a wideband tunable fibre laser with flat power spectrum. The tuning range of the wavelength spacing is continuous within a 35 nm spectral range, and the power difference between both lasing wavelengths can be easily adjusted and controlled by a variable optical attenuator. The total output power can approximately keep unchangeable when the wavelength spacing and the power difference between both lasing wavelengths are continuously tuned and changed. The maximum total output power of the laser system is about 2.22 W.

Novel highly birefringent photonic bandgap fibres (PBGFs) are obtained by filling of a high index material in the air holes of total internal reflection birefringent photonic crystal fibres. The effect of the filling high index material on the transmission characteristics has been theoretically investigated. The photonic bandgap has been achieved by using plane-wave method. Moreover, the phase and group modal birefringence have been studied by a full-vector finite-element method. Numerical results show that very high group and phase modal birefringence with magnitude of order of 10−2 and 10−3 has been respectively acquired, which is much higher than those of the non-filled fibres. Furthermore, strong coupling between surface modes and the fundamental modes has been found in the bandgap of the birefringent PBGFs, whose effect on the birefringence and confinement loss has also been discussed.

In this paper, a novel output-power controllable erbium-doped fibre laser, based on a strain-applied high-birefringence fibre loop mirror (HBFLM), was proposed and demonstrated. The reflectivity of HBFLM could be changed from about 0.8% to 100% because the fibre length and birefringence of the high-birefringence fibre (HBF) were altered via bonding a part of HBF to the centric surface of an uniform-strength cantilever beam and applying different stress at end of the beam. As a result, the laser output power could be adjusted and controlled in a dynamic range of more than 33 dB. The laser is not only a controllable and adjustable output-power laser with simple configuration and low cost, but also can be used for optimizing the output characteristics of a linear cavity laser via easily finding out the optimized reflectivity of the reflectors.

We describe a novel erbium-doped fiber ring laser utilizing the backward amplified spontaneous emission (ASE) power as a secondary pump source so that it can operate in L-band stably. The output wavelength can be tuned in a wide range of 45 nm, from 1560 to 1605 nm. We also compared this scheme with the condition of not using the ASE as secondary pump source, and found this scheme could improve the performance of the laser when using the same components.

In this article, we reported a polarization orthogonal single-longitudinal-mode distributed Bragg reflector (DBR) fiber laser. The laser operated robustly in single longitudinal mode and dual polarizations with frequency difference of 976.93 MHz. This laser has simple structure as well as frequency adjustable. It can be used in a wide range of communication, sensor, and spectroscopic applications. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1658–1660, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23454

A passive Q-switched large-mode-area Yb-doped fibre laser is demonstrated using a GaAs wafer as the saturable absorber. A high Yb doping concentration double-clad fibre with a core diameter of 30 μm and a numerical aperture of 0.07 is used to increase the laser gain volume, permitting greater energy storage and higher output power than conventional fibres. The maximum average output power is 7.2 W at 1080 nm wavelength, with the shortest pulse duration of 580 ns and the highest peak power of 161 W when the laser is pumped with a 25 W diode laser operating at 976 nm. The repetition rate increases with the pump power linearly and the highest repetition rate of 77 kHz is obtained in the experiment.

In this paper, we analyzed the frequency splitting phenomena when distributed Bragg reflector (DBR) fiber laser was influenced by lateral pressure. We gave the relationship of the frequency interval and the lateral pressure. This frequency splitting phenomena is based on Intracavity birefringent effects which are modulated by lateral pressure. So, this frequency splitting phenomena could be used in sensing pressure in the future. The pressure sensor which is based on the frequency splitting had more merits such as simple structure and frequency readable. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2628–2630, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22818

We propose and demonstrate a new concept of stable narrow-line-width and close wavelength spacing dual-wavelength lasing in an Er-doped fibre ring laser (EDFRL) by cleaving the spectrum with a wavelength-selective component in the EDFRL. A fibre loop mirror (FLM) combining with a polarization controller (PC) acts as the cleaver. The cleaver can produce a fine pectinate spectrum. By adjusting the PC, the fine pectinate spectrum can be so changeable that cleaving the spectrum of a fibre Bragg grating (FBG) into two parts. As a result, we obtain the dual-wavelength fibre lasering with a bandwidth of only 0.03 nm and a wavelength spacing of only 0.07 nm. Furthermore, the laser can also perform stable switchable single wavelength or stable different-bandwidth dual-wavelength by carefully adjusting the PC at room temperature.

A high-power Er3+/Yb3+-codoped double-cladding all-fibre amplifier was successfully demonstrated and experimentally investigated. The amplifier could be operated with a maximum output power of 2.18 W and 2.11 W at 1541 nm and 1550 nm wavelengths, respectively, when the maximum pump power was 6.07 W. The power conversion efficiency was up to 35.6% and 34.4% at the two wavelengths, respectively. The output power and the gain were greater than 2.00 W and 20.0 dB, respectively, in the wavelength range from 1539 nm to 1565 nm for 20.0 mW input signal power. The gain fluctuation and the noise figure around 1550 nm wavelength were less than 0.3 dB and 6.0 dB, respectively.

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Multiwavelength operation of a linear cavity erbium-doped fibre laser (EDFL) is proposed and demonstrated. A 3-dB fibre loop mirror and a high birefringence (HiBi) fibre loop mirror are utilized as the cavity reflectors. By utilizing the wavelength-dependent polarization rotation induced by the HiBi fibre loop mirror and by using a fibre polarizer to control the intracavity polarization state, the polarization states of different wavelengths are diversified. Therefore, the polarization hole burning (PHB) effect has been greatly enhanced and the homogeneous broadening of erbium-doped fibre is suppressed to a large extent. By simply tuning a polarization controller, we experimentally obtained simultaneous lasing of four and five wavelengths with wavelength spacing of ~1.8 nm and less than 2 nm at room temperature, respectively. The repeated scans show that all of these lasers have good stability.

All-fibre high power erbium–ytterbium co-doped double clad fibre lasers are proposed and demonstrated. By using different back-cavity mirrors, the different double clad fibre lasers are constructed. It is experimentally found that the output behaviour of laser can be controlled by a back-cavity mirror. The lower the reflectivity of the back-cavity mirror, the higher the output power and the high the slop efficiency. The maximum output power is about 1.6 W and the slop efficiency is 27.6%.

A tunable Yb-doped double-clad fibre (YDCF) laser by tuning the fibre Bragg grating (FBG) is successfully demonstrated. The FBG was fabricated in the YDCF directly, resulting in low splicing loss and compact configuration. A continuous tuning range of 15.6 nm from 1046.6 nm to 1062.2 nm is achieved. The laser linewidth is smaller than 0.1 nm in the whole tuning range. A maximum output power 117 mW is achieved when the pump power is 332 mW. The laser oscillation is quite stable in the whole operation.

A polarization controlled switchable multiwavelength erbium-doped fibre laser with overlapping cavities is proposed. The wavelengths are specified by two Bragg gratings in polarization-maintaining PANDA fibre. The proposed laser can be designed to be operated in stable four-wavelength or wavelength switching modes only by simple adjustment of two polarization controllers. For wavelength switching, four single-wavelength, six dual-wavelength, and four three-wavelength operations have been obtained. The minimum wavelength spacing is only about 0.4 nm.

A simple actively mode-locked fibre ring laser is proposed and successfully demonstrated to generate switchable dual-wavelength picosecond pulses using a Bragg grating in a polarization-maintaining fibre. The wavelength spacing specified by the grating is only 0.52 nm. The proposed laser can be made to operate in stable dual-wavelength or switch between wavelengths at room temperature, by simple adjustment of a polarization controller.

A novel Yb3+-doped double-clad fibre laser based on a double-clad fibre Bragg grating is presented. The fibre Bragg grating, as the output mirror, has been formed in Yb3+-doped double-clad fibre with the phase-mask method. When the input pump power is 2.8 W, the maximum laser output power is 570 mW, with

A novel Yb3+-doped four-wavelength double clad fibre laser based on a Fabry-Perot filter, and pumped by a 976 nm laser diode is presented. Its output laser wavelengths are 1085, 1090, 1095 and 1010 nm, respectively. The laser exhibits 0.32 nm line-width, 1.5 W laser output power, 40 dB signal-to-noise ratio and 66% slope efficiency.

We study the pulsed laser ablation of wurtzite gallium nitride (GaN) films grown on sapphire, using the femtosecond laser beam at a central wavelength of 800 nm as the source for the high-speed ablation of GaN films. By measuring the backscattered Raman spectrum of ablated samples, the dependence of the ablation depth on laser fluence with one pulse was obtained. The threshold laser fluence for the ablation of GaN films was determined to be about 0.25 J/cm2. Laser ablation depth increases with the increasing laser fluence until the amount of removed material is not further increased. The ablated surface was investigated by an optical surface interference profile meter.

A novel actively mode-locked fiber laser for generating dual-wavelength picosecond pulses is proposed by using a Fabry-Perot laser diode as the modulator in the ring cavity. A linear chirped fiber grating was used as a wavelength selector and produces temporal-spectral multiplexing of the pulses in the gain medium to reduce gain cross-saturation effects. About 2-GHz stable dual-wavelength pulses with a wavelength spacing of 0.92 nm at room temperature were experimentally demonstrated and the wavelengths could be tuned in a range of about 3 nm.

A simple configuration to perform wavelength switching in an actively mode-locked fiber ring laser is demonstrated. A Fabry-Perot laser diode was used as a modulator and a HiBi fiber loop mirror was used as a periodic multichannel wavelength filter in the cavity. By setting the channel spacing of nm can be achieved by tuning the fiber loop mirror filter. In the wavelength-switched process, the modulation frequency was not required to be changed.

A novel and simple approach of temperature-independent stress and displacement bidirectional sensing tuned by an applied bilateral cantilever beam is proposed and demonstrated. The 3dB bandwidth of fibre gratings is linear with respect to the stress and displacement in the tuning range of 16 nm. The sensing sensitivities of the stress and displacement are 5.76 nm/N and 0.941 nm/mm, respectively.

A novel Yb3+-doped double-clad silica fibre with rectangular inner cladding was designed and developed by using the modified chemical vapour deposition process, solution-doping and optical machining all together. The dimensions of the inner cladding are 100×70 µm, and Yb3+-doped concentration in the core is about 0.24 wt.%. The operation of the fibre laser pumped by inner cladding is reported. The threshold of the laser is 34 mW. When the pump power launched is 141 mW, the laser output is 84 mW at the wavelength 1075.6 nm, and the slope efficiency is 77%.

A novel four-wavelength all-fibre laser based on fibre Bragg gratings is presented. The four wavelengths are 1555.8, 1556.6, 1557.4 and 1558.2 nm, respectively. Each output laser is 1 mW in power. The suppression ratio between adjacent wavelengths is >30 dB. The laser was applied in a wavelength division multiplexing (WDM) system and the 100 km transmission of 1.2 Gb/s nonreturn-to-zero code, 1.2 Gb/s return-to-zero code, 2.5 GHz analogue signal and 5 GHz analogue signal was realized with it.