Dynamics of erbium-doped fibre laser with optical delay feedback and chaotic synchronization

The dynamical behaviour of the erbium-doped fibre single-ring laser with an optical delay feedback is discussed. Simulation shows that as the delay rate increases, the lasing light displays period-doubling which leads to chaos and via reverse period-doubling route returns from chaos to periodic. At a particular delay rate the intermittently chaotic route to chaos is also observed. The identical synchronization based on chaos in this ring laser is demonstrated by numerical simulation.

Transition state to mode locking in a passively mode-locked erbium-doped fibre ring laser

The transition state between the continuous wave region and the mode-locked region in a passively mode-locked erbium-doped fibre ring laser has been experimentally observed by utilizing the nonlinear polarization rotation technique. When the pump power reaches the mode-locked threshold, the metastable pulse train with a tunable repetition rate is obtained in the transition from the continuous wave state to the passive mode-locked state via proper adjustment of the polarization controller. A simpie model has been established to explain the experimental observation.

An experiment of dynamical behaviours in an erbium-doped fibre-ring laser with loss modulation

This paper reports a systematic experimental investigation on the dynamics in the low-frequency region in an erbium-doped fibre-ring laser with loss modulation. A rich variety of bifurcation is analyzed through the bifurcation diagram and structured with the concept of the winding numbers. The coexistence of multiple attractors and the crisis that appear in the saddle-node bifurcations, and an interesting structure of bifurcation which is similar to the bifurcations in high-frequency range, have been observed.

Different operation states of soliton pulses in an erbium-doped fibre ring laser

We report on the experimental observation of soliton pulses in an erbium doped fibre ring laser. The passive mode-locking is achieved using the nonlinear polarization rotation technique. By adjusting the pump power and the intracavity polarization controllers, a normal soliton, a stable 8th harmonic mode-locked pulse and a noise-like pulse have been observed in our laser. The experimental results revealed that the noise-like pulse is not suitable for the optical telecommunication, and in order to obtain the stable harmonic mode-locked soliton, a strong unstable CW laser field is necessary to mediate global soliton interaction. The formation mechanism of the harmonic mode-locked pulse has also been analysed.

Dual-wavelength dissipative soliton operation of an erbium-doped fibre laser using a nonlinear polarization rotation technique

We report on the generation of dual-wavelength dissipative solitons in a passively mode-locked fibre laser with a net normal dispersion using the nonlinear polarization rotation （NPR） technique. Taking the intrinsic advantage of the intracavity birefringence-induced spectral filtering effect in the NPR-based ring laser cavity, the dual-wavelength dissipative solitons are obtained. In addition, the wavelength separation and the lasing location of the dual-wavelength solitons can be flexibly tuned by changing the orientation of the polarization controller.

Theoretical study and optimization of a high power mid-infrared erbium-doped ZBLAN fibre laser

Based on the rate equations describing the erbium-doped fluoride glass （ZBLAN） fibre lasers with different pumping configurations being taken into account, this paper presents theoretical calculations related to the dynamic population density and the operation performance of a high power mid-infrared all-fibre erbium-doped ZBLAN fibre laser. It shows that the ground-state absorption, excited-state absorption and energy-transfer-upconversion processes co-exist and produce a population balance, causing the laser to operate stably at a continuous wave state. A good agreement between the theoretical results and recent experimental measurement is obtained. Furthermore, the laser structure parameters including fibre length, reflectance of output fibre Bragg grating and pumping configurations are quantitatively optimised to achieve the best performance. The results show, as expected, that the slope efficiency of the fibre laser can be improved significantly through optimisation, which then provides an important guide for the design of high-performance mid-infrared erbium-doped ZBLAN fibre lasers.

Overview of Jute Fibre as Thermoplastic Matrix Polymer Reinforcement

Recent decades have seen a substantial increase in interest in research on natural fibres that is aligned with sustainable development goals(SDGs).Due to their renewable resources and biodegradability,natural fiberreinforced composites have been investigated as a sustainable alternative to synthetic materials to reduce the usage of hazardous waste and environmental pollution.Among the natural fibre,jute fibre obtained from a bast plant has an increasing trend in the application,especially as a reinforcement material.Numerous research works have been performed on jute fibre with regard to reinforced thermoset and thermoplastic composites.Nevertheless,current demands on sustainable materials have required new developments in thermoplastic composites.In this paper,the author reviews jute plants as reinforcement materials for thermoplastic matrix polymers.This review provides an overview of the sustainability of jute plants as reinforcement material for thermoplastic matrix polymers.The overview on jute based thermoplastic composites focused on the thermal behavior and mechanical properties.Apart from physical,chemical,and mechanical properties,the study also covers the current and perspectives for future research challenges faced by the researchers on jute fibre reinforced thermoplastic composites.

Optical Fibre Communication Feature Analysis and Small Sample Fault Diagnosis Based on VMD-FE and Fuzzy Clustering

To solve the problems of a few optical fibre line fault samples and the inefficiency of manual communication optical fibre fault diagnosis,this paper proposes a communication optical fibre fault diagnosis model based on variational modal decomposition(VMD),fuzzy entropy(FE)and fuzzy clustering(FC).Firstly,based on the OTDR curve data collected in the field,VMD is used to extract the different modal components(IMF)of the original signal and calculate the fuzzy entropy(FE)values of different components to characterize the subtle differences between them.The fuzzy entropy of each curve is used as the feature vector,which in turn constructs the communication optical fibre feature vector matrix,and the fuzzy clustering algorithm is used to achieve fault diagnosis of faulty optical fibre.The VMD-FE combination can extract subtle differences in features,and the fuzzy clustering algorithm does not require sample training.The experimental results show that the model in this paper has high accuracy and is relevant to the maintenance of communication optical fibre when compared with existing feature extraction models and traditional machine learning models.

BTMA’s advanced fibre focus at Techtextil 2024

New fibres continue to be developed for a wide range of technical textile applications.Currently,they include fibres based on organic or recycled feedstocks to meet sustainability targets and others with new functional properties for advanced high performance applications.Many of them were showcased at the forthcoming Techtextil 2024 exhibition which takes place in Frankfurt,Germany,from April 23-26.The development of specific multifilaments,monofilaments and nonwovens for niche fibre applications–over 70 to date–is very much the specialist field of BTMA member Fibre Extrusion Technologies(FET),along with designing the bespoke fibre extrusion and spunbond and meltblown nonwoven systems to successfully produce them.

Preparation of pitch precursor with excellent spinnability for general-purpose carbon fibre using coal tar pitch as raw material

Tetrahydrofuran(THF) extract of coal tar pitch(CTP) was used instead of blending CTP with pretreated pyrolysis fuel oil to prepare an isotropic pitch precursor with excellent spinnability for general-purpose carbon fibre through bromination-dehydrobromination. The feasibility and effectiveness of synthesising an isotropic pitch precursor derived from THF-soluble(CTP-THFs) is demonstrated in this study.The results show that CTP-THFs contains more light components than CTP;CTP-THFs and CTP monomer proportions were 62.52% and 45.32%, respectively. However, based on comparisons of CTP-THFsBr0 and CTPBr0 characterisations, CTP-THFs exhibits better polycondensation than CTP. Bromination-dehydrobro mination promotes polycondensation of pitch precursors, leading to greater carbon aromaticity in CTP-THFsBr5, CTP-THFsBr10, and CTP-THFsBr15 than that in CTP-THFsBr0 and CTPBr0. CTP-THFsBr5 and CTP-THFsBr10 have excellent spinnability even with softening points as high as 230 ℃. The pericondensed carbon and carbon aromaticity of CTP-THFsBr5 and CTP-THFsBr10 are high owing to the higher degree of polycondensation;however, they still possess a more linear molecular structure. The as-prepared carbon fibre exhibits homogeneity and uniformity, and the mechanical performance is comparable with that of commercial general-purpose carbon fibre products.

Characteristic of Fresh and Harden Properties of Polyvinyl Alcohol Fibre Reinforced Alkali Activated Composite

Fibre can enhance the mechanical properties of cement-based composites,but fibre also degrades their workability.However,the quantitative effects of fiber content and length-diameter ratio on alkali-activated materials are still unclear.Various aspect ratio,volume fraction of polyvinyl alcohol fibre(PVAF),and various water-binder ratio were employed to prepare a total of 26 groups of fibre reinforced alkali-activated composite(FRAAC).The influence of PVAF fibre factor(product of fiber volume fraction and length-diameter ratio)on flowability,compactness,strength,and crack fractal dimension of FRAAC was researched.The influence of water-binder ratio on the plastic viscosity of FRAAC was more significant than that on the yield stress.When fibre factor was lower than critical value of 150,the influence of fibres could be overlooked.The reason was that the space between fibres was distant,so the flowability of FRAAC was not impacted by PVAF.At this time,fibres were challenging to restrict the cracks in matrix and increase their mechanical properties.When fibre factor was higher than critical value 150 and lower than density packing value 450,the flexural strength,compressive strength and crack fractal dimension of FRAAC were considerably enhanced,and the FRAAC could still flow easily under dead weight.When fibre factor were above 450,noteworthy fibre balling considerably decreased the flowability,leading to poor solidity and reduced compressive strength.Hence,the ideal content of PVAF in alkali activated composite is between 150/(l/d)and 450/(l/d).

Are yarn quality prediction tools useful in the breeding of high yielding and better fibre quality cotton(Gossypium hirsutum L.)?

Results The population had large variations for lint yield,fibre properties,predicted yarn properties,and composite fibre quality values.Lint yield with all fibre quality traits was not correlated.When the selection was conducted first to keep those with improved fibre quality,and followed for high yields,a large proportion in the resultant populations was the same between selections based on Cottonspec predicted yarn quality and HVI-measured fibre properties.They both exceeded the selection based on FQI and Background The approach of directly testing yarn quality to define fibre quality breeding objectives and progress the selection is attractive but difficult when considering the need for time and labour.The question remains whether yarn prediction tools from textile research can serve as an alternative.In this study,using a dataset from three seasons of field testing recombinant inbred line population,Cottonspec,a software developed by the Commonwealth Scientific and Industrial Research Organisation(CSIRO)for predicting ring spun yarn quality from fibre properties measured by High Volume Instrument(HVI),was used to select improved fibre quality and lint yield in the population.The population was derived from an advanced generation inter-crossing of four CSIRO conventional commercial varieties.The Cottonspec program was able to provide an integrated index of the fibre qualities affecting yarn properties.That was compared with selection based on HVI-measured fibre properties,and two composite fibre quality variables,namely,fibre quality index(FQI),and premium and discount(PD)points.The latter represents the net points of fibre length,strength,and micronaire based on the Premiums and Discounts Schedule used in the market while modified by the inclusion of elongation.PD points.Conclusions The population contained elite segregants with improved yield and fibre properties,and Cottonspec predicted yarn quality is useful to effectively capture these elites.There is a need to further develop yarn quality prediction tools through collaborative efforts with textile mills,to draw better connectedness between fibre and yarn quality.This connection will support the entire cotton value chain research and evolution.

A kind of multiwavelength erbium-doped fiber laser based on Lyot filter

A multiwavelength tunable ring-cavity erbium-doped fiber laser(EDFL)based on a Lyot filter was presented.For the proposed Lyot filter,a comb filter consisting of an EDF-polarization-maintaining fiber(EDF-PMF),a polarization controller(PC),and a circulator with four ports was used to suppress the mode competition.The light transmission direction was guaranteed by the circulator.For the proposed fiber laser,tunable single,dual,triple,quadruple,quintuple,sextuple,and septuple wavelengths were realized.A single-wavelength laser output with an optical signal-to-noise ratio(SNR)of up to30.56 dB was realized,and a tuning range of 1590.54 nm to 1599.54 nm was achieved by tuning the PC.The stability of the single,dual,triple,and quadruple-wavelength center power fluctuations was less than 0.05 dB,0.98 dB,5.07 dB,and7.71 dB respectively.When the laser was operated in the multiwavelength condition,the SNR was more than 20.97 dB.The proposed erbium-doped fiber laser is suitable for fiber-sensing system applications.

Aerodynamic shape and drag scaling law of a flexible fibre in a flowing medium

The study of a flexible body immersed in a flowing medium is one of the best way to find its aerodynamic shape.This Letter revisited the problem that was first studied by Alben et al.(Nature 420,479–481,2002).To determine the aerodynamic shape of the fibre,a simpler approach is proposed.A universal drag scaling law is obtained and the universality of the Alben-Shelley-Zhang scaling law is confirmed by using dimensional analysis.A complete Maple code is provided for finding aerodynamic shape of the fibre in the flowing medium.

Assessing genetic variation in Gossypium barbadense L.germplasm based on fibre characters

Background Gossypium barbadense L.has specific fibre in terms of its length,strength,and fineness,and known as extra-long staple(ELS) cotton,Sea–Island cotton,or Egyptian cotton.Narrow genetic base with less genetic variability is observed in G.barbadense germplasm.Hence,this study was aimed to evaluate the genetic variability present in 108 germplasm accessions of G.barbadense and to identify the superior genotypes based on the fibre traits.Results We evaluated 108 accessions for five fibre quality traits along with three checks in augmented block design.All fibre traits showed significant differences among genotypes,indicating that there is genetic potential for improvement.Fibre strength and micronaire(MIC) showed high phenotypic and genotypic coefficients of variation.High heritability combined with high genetic advance as percentage of mean(GAM) was recorded for fibre length,strength,and micronaire.Fibre strength and fibre length were significantly correlated with each other,while both showed negative correlation with micronaire.Principal component analysis and Biplot analysis showed that uniformity index discriminated all the genotypes in higher level,while fibre length and strength were medium in discrimination power.Biplot revealed genotypes DB 16,EC959191,GSB 39,ARBB 20,5746U,EA 203,and EA 201 were genetically diverse.Hierarchal cluster analysis based on unweighted paired group method using arithmetic average(UPGMA) grouped the genotypes into four clusters,with each cluster consisting of 4,18,48,and 38 genotypes,respectively.Conclusion Among the genotypes,34 for fibre length(> 35 mm),18 for fibre strength(> 40.4 g·tex^(-1)) and 66 for micronaire(3.7-4.2,A grade) were identified as potential accessions based on their superiority.The superior fibre genotypes identified in this study are potential lines for the ELS cotton breeding program.

Materials Selection of Thermoplastic Matrices of Natural Fibre Composites for Cyclist Helmet Using an Integration of DMAIC Approach in Six Sigma Method Together with Grey Relational Analysis Approach

Natural fibre reinforced polymer composite(NFRPC)materials are gaining popularity in the modern world due to their eco-friendliness,lightweight nature,life-cycle superiority,biodegradability,low cost,and noble mechanical properties.Due to the wide variety of materials available that have comparable attributes and satisfy the requirements of the product design specification,material selection has become a crucial component of design for engineers.This paper discusses the study’s findings in choosing the suitable thermoplastic matrices of Natural Fibre Composites for Cyclist Helmet utilising the DMAIC,and GRA approaches.The results are based on integrating two decision methods implemented utilising two distinct decision-making approaches:qualitative and quantitative.This study suggested thermoplastic polyethylene as a particularly ideal matrix in composite cyclist helmets during the selection process for the best thermoplastic matrices material using the 6σtechnique,with the decision based on the highest performance,the lightest weight,and the most environmentally friendly criteria.The DMAIC and GRA approach significantly influenced the material selection process by offering different tools for each phase.In the future study,selection technique may have been more exhaustive if more information from other factors had been added.

Experimental Study and Failure Criterion Analysis of Rubber Fibre Reinforced Concrete under Biaxial Compression-Compression

In order to examine the biaxial compression-compression properties of rubber fibre reinforced concrete(RFRC),an experimental study on RFRC under different lateral compressive stresses was carried out by considering different rubber replacement rates and polypropylene fibre contents.The failure modes and mechanical property parameters of different RFRC working conditions were obtained from the experiment to explore the effects of rubber replacement rate and polypropylene fibre content on the biaxial compression-compression properties of RFRC.The following conclusions were drawn.Under the influence of lateral compressive stress,the biaxial compression-compression failure mode gradually developed from a columnar pattern to a flaky pattern,suggesting that the incorporation of rubber and polypropylene fibres into the concrete resulted in a significant change in the development of cracks.For different rubber replacement rates and polypropylene fibre contents,the vertical compressive stress exhibited the same developing trend under the influence of lateral compressive stress.Specifically,the lateral compressive stress imposed the minimum effect on the vertical compressive stress when the rubber replacement rate and polypropylene fibre content were 20%and 0.4%,respectively,and imposed the maximum effect when the rubber replacement rate and polypropylene fibre content were 20%and 0%,respectively.With the increase of rubber replacement rate,the vertical peak stress was significantly reduced,which implies that an appropriate amount of polypropylene fibres can increase the vertical peak stress to a certain extent.Then,the biaxial compression-compression mechanism of RFRC was analysed from the microscopic level by using scanning electron microscope(SEM).Meanwhile,based on Kupfer’s biaxial compression-compression failure criterion and the octahedral stress space,a biaxial compression-compression failure criterion for RFRC was proposed,which was proven to have good applicability.The research results of this study provide important theoretical basis for the engineering application and development of RFRC.

Effect of Fibre Size on Mechanical Properties and Surface Roughness of PLA Composites by Using Fused Deposition Modelling (FDM)

Naturalfibre as a reinforcing agent has been widely used in many industrial applications.Nevertheless,several factors need to be considered,such as the size and weight percentage of thefibre used in binding.Using fused deposition modelling(FDM),this factor was investigated by varying the size of naturalfibre as the responding variable with afixed weight percentage of kenaffibre.The process of modifying the naturalfibre in terms of size might increase the dispersion of kenaffibre in the polymer matrix and increase the adhesion bonding between thefibre and matrix of composites,subsequently improving the interfacial bonding between these two phases.In this paper,the effect offibre size was evaluated by performing the mechanical test,Scanning Electron Micrograph(SEM)to observe the morphology of the composites,and also by surface analysis.The surface roughness was visualised using a 3D profilometer and thefigure was illustrated as colour shading in the image.The composite withfibre size≤100μm displayed better tensile andflexural strength,compared to other sizes.In conclusion,by reducing the size of thefibre,the composites could develop high strength performance for industrial applications.

Can waste textiles be completely transformed into fibres?

The advancement and novel technologies in materials science have been steadily growing toward adopting ethical practices.To reduce the stress on the environment the producers integrate novel materials to extend traditional functionality.They develop modern fibers that are eco-friendly,light,resilient,mechanically flexible,and easy to process.Moreover,novel fabrics are acquiring unique properties such as sensory capabilities,electrical conductivity,and data transmission.Cloths with characteristics such as hydrophobic cotton,plant-based textiles,antimicrobial fabrics,and shape memory polymers show versatility in textile innovations.Overall,these textile innovations provide sustainable alternatives,which are commercially viable and suitable for large-scale production.