Hollow and filled fiber bragg gratings in nano-bore optical fibers

To combine the technical functions and advantages of solid-core fiber Bragg gratings(FBGs) and hollow-core optical fibers(HCFs), the hollow and filled FBGs in nano-bore optical fibers(NBFs) with nano-bore in the GeO2-doped core are proposed.The fundamental mode field, effective mode index, and confinement loss of NBF with 50 nm–7 μm-diameter hollow and filled nano-bore are numerically investigated by the finite element method.The reflected spectra of FBGs in NBFs are obtained by the transmission matrix method.The hollow FBGs in NBFs can be acheived with ~5% power fraction in the bore and the ~0.9 reflectivity when bore diameter is less than 3 μm.The filled FBGs can be realized with^1% power fraction and 0.98 reflectivity with different fillings including o-xylene, trichloroethylene, and chloroform for 800-nm bore diameter.The feasibility of the index sensing by our proposed NBF FBG is also analyzed and discussed.The experimental fabrication of hollow and filled FBGs are discussed and can be achieved by current techniques.The aim of this work is to establish a principle prototype for investigating the HCFs and solid-core FBGs-based fiber-optic platforms,which are useful for applications such as the simultaneous chemical and physical sensing at the same position.

Deformation Analysis of Micro/Nano Indentation and Diamond Grinding on Optical Glasses

The previous research of precision grinding optical glasses with electrolytic in process dressing （ELID） technology mainly concentrated on the action of ELID and machining parameters when grinding, which aim at generating very ＂smoothed＂ surfaces and reducing the subsurface damage. However, when grinding spectrosil 2000 and BK7 glass assisted with ELID technology, a deeply comparative study on material removal mechanism and the wheel wear behaviors have not been given yet. In this paper, the micro/nano indentation technique is initially applied for investigating the mechanical properties of optical glasses, whose results are then refereed to evaluate the machinability. In single grit diamond scratching on glasses, the scratching traces display four kinds of scratch characteristics according to different material removal modes. In normal grinding experiments, the result shows BK7 glass has a better machinability than that of spectrosil 2000, corresponding to what the micro/nano indentation vent revealed. Under the same grinding depth parameters, the smaller amplitude of acoustic emission （AE） raw signals, grinding force and grinding force ratio correspond to a better surface quality. While for these two kinds of glasses, with the increasing of grinding depth, the variation trends of the surface roughness, the force ratio, and the AE raw signals are contrary, which should be attributed to different material removal modes. Moreover, the SEM micrographs of used wheels surface indicate that diamond grains on the wheel surface after grinding BK7 glass are worn more severely than that of spectrosil 2000. The proposed research analyzes what happened in the grinding process with different material removal patterns, which can provide a basis for producing high-quality optical glasses and comprehensively evaluate the surface and subsurface integrity of optical glasses.

Research on Infrared Emissivity and Laser Reflectivity of Sn_(1−x)Er_(x)O_(2)Micro/Nanofibers Based on First-Principles

Sn_(1−x)Er_(x)O_(2)(x=0%,8%,16%,24%)micro/nanofibers were prepared by electrospinning combined with heat treatment using erbium nitrate,stannous chloride and polyvinylpyrrolidone(PVP)as raw materials.The target products were characterized by thermogravimetric analyzer,X-ray diffrotometer,fourier transform infrared spectrometer,scanning electron microscope,spectrophotometer and infrared emissivity tester,and the effects of Er^(3+)doping on its infrared and laser emissivity were studied.At the same time,the Sn_(1−x)Er_(x)O_(2)(x=0%,16%)doping models were constructed based on the first principles of density functional theory,and the related optoelectronic properties such as their energy band structure,density of states,reflectivity and dielectric constant were analyzed,and further explained the mechanism of Er^(3+)doping on SnO_(2)infrared emissivity and laser absorption from the point of electronic structure.The results showed that after calcination at 600℃,single rutile type SnO_(2)was formed,and the crystal structure was not changed by doping Er^(3+).The calcined products showed good fiber morphology,and the average fiber diameter was 402 nm.The infrared emissivity and resistivity of the samples both decreased first and then increased with the increase of Er^(3+)doping amount.When x=16%,the infrared emis-sivity of the sample was at least 0.71;and Er^(3+)doping can effectively reduce the reflectivity of SnO_(2)at 1.06μm and 1.55μm,when x=16%,its reflectivity at 1.06μm and 1.55μm are 50.5%and 40%,respectively,when x=24%,the reflectivity at 1.06μm and 1.55μm wavelengths are 47.3%and 42.1%,respectively.At the same time,the change of carrier concentration and electron transition before and after Er^(3+)doping were described by first-principle calculation,and the regulation mechanism of infrared emissivity and laser reflectivity was explained.This study provides a certain experimental and theoretical basis for the development of a single-type,light-weight and easily prepared infrared and laser compatible-stealth material.

Spectra of spontaneous Raman scattering in taper-drawn micro/nano-fibers

We study the spontaneous Raman scattering （RS） in taper-drawn micro/nano-fibers （MNFs） by employing the photon counting technique. The spectra of RS in five MNFs, which are fabricated by using different heating flames （hydrogen flame or butane flame） and with different diameters, are measured within a frequency shift range of 1435 cm- 1_3200 cm- 1. From the measured spectra, we observe the RS peaks originated from silica and a unique RS peak with a frequency shift of - 2905 cm-1 （- 87.2 THz）. Unlike the former ones, the latter one is not observable in conventional optical fibers. Furthermore, the unique peak becomes obvious and starts to rapidly increase with the decrease of the diameter of MNFs when the diameter is smaller than 2 μm, and the intensity of the unique peak significantly depends on the heating flame used in the fabricating process. Our investigation is useful for the entanglement generation or optical sensing using taper-drawn MNFs.

DISTRIBUTED MICROBEND FIBER-OPTIC STRAIN SENSOR

The distributed strain sensor has significant application in real time measurement of strain status for large and important engineering structures such as aircraft, bridge and dam. In this paper, a quasi distributed optical fiber strain sensor system is set up using optical time domain reflect technique. The local strain sensors based on a novel microbend configuration are designed and applied to measure local strains along the optical fiber. As the result of the experimental research, the microbend sensors show high sensitivity, good linearity and repeatability in certain operation range.

Flexible Optical Waveguide Bent Loss Attenuation Effects Analysis and Modeling Application to an Intrinsic Optical Fiber Temperature Sensor

The temperature dependence of the bending loss light energy in multimode optical fibers is reported and analyzed. The work described in this paper aims to extend an initial previous analysis concerning planar optical waveguides, light energy loss, to circular optical waveguides. The paper also presents à novel intrinsic fiber optic sensing device base on this study allowing to measure temperatures parameters. The simulation results are validated theoretically in the case of silica/silicone optical fiber. A comparison is done between results obtained with an optical fiber and the results obtained from the previous curved optical planar waveguide study. It is showed that the bending losses and the temperature measurement range depend on the curvature radius of an optical fiber or waveguide and the kind of the optical waveguide on which the sensing process is implemented.

Optical Micro/Nano Fibers Enabled Smart Textiles for Human-Machine Interface

Wearable human-machine interface(HMI)is an advanced technology that has a wide range of applications from robotics to augmented/virtual reality(AR/VR).In this study,an optically driven wearable human-interactive smart textile is proposed by integrating a polydimethylsiloxane(PDMS)patch embedded with optical micro/nanofibers(MNF)array with a piece of textiles.Enabled by the highly sensitive pressure dependent bending loss of MNF,the smart textile shows high sensitivity(65.5 kPa^(−1))and fast response(25 ms)for touch sensing.Benefiting from the warp and weft structure of the textile,the optical smart textile can feel slight finger slip along the MNF.Furthermore,machine learning is utilized to classify the touch manners,achieving a recognition accuracy as high as 98.1%.As a proof-of-concept,a remote-control robotic hand and a smart interactive doll are demonstrated based on the optical smart textile.This optical smart textile represents an ideal HMI for AR/VR and robotics applications.

New Measuring Temperature Setup with Optical Probe

Abstract: A new setup of measuring temperature is developed, which the probe is a micro- power consumptive one with CMOS circuit and is driven by optical power. For transmitting the measured signal and optical power signal in a long distance, the fiber technology is applied in this setup.

Mechanical Properties of Submicron Glass Fiber Reinforced Vinyl Ester Composite

Vinyl ester (VE) resin inherently has intrinsic brittleness due to its high cross-link density. To improve mechanical performance, micro/nano fillers are widely used to modify this matrix. In present study, glass fiber in submicron scale at low contents was added into VE to prepare submicron composite (sMC). The impact resistance of un-notched sMC degraded with the increase of sGF content while that of notched-sMC remained the unchanged. Flexural properties of sMCs also were the same with that of neat resin. The results of Dynamic mechanical analysis (DMA) test showed the slight increase of storage modulus and the decrease of tan delta value in the case of sMC compared to those of un-filled matrix. However, the Mode I fracture toughness of sMC improved up to 26% and 61% corresponding to 0.3 and 0.6 wt% glass fiber used. The compact tension sample test suggests that there is the delay of crack propagation under tensile cyclic load in resin reinforced by submicron glass fiber. The number of failure cycle enlarged proportionally with the increment of sGF content in matrix.

A low-cost and high-strength basalt/carbon fiber reinforced polymer improved by imitating tree-root micro/nano aramid short fiber

The high-strength Basalt Carbon Fiber Reinforced Polymer(BCFRP)composites had been manufactured by guiding Imitating Tree-root Micro/Nano Aramid Short Fiber(ITMNASF)into the interlayer of Basalt Fiber(BF)and Carbon Fiber(CF)plies to form thin interleaving,and various mass proportions of IT-MNASF were designed to discuss the reinforcing effect on the BCFRP heterogeneous composites.The results of three points bending tests showed that flexural strength and energy absorption of 4wt%IT-MNASF reinforced BCFRP heterogeneous composites had been improved by 32.4%and 134.4%respectively compared with that of unreinforced specimens.The 4wt%IT-MNASF reinforced BCFRP specimens showed both a greater strength and a lower cost(reduced by 31%around)than that of plain CFRP composites.X-ray micro-computed tomography scanning results exhibited that the delamination-dominated failure of plain BCFRP composites was changed into multi-layer BF and CF fabrics damage.The reinforcing mechanism revealed that the introduced IT-MNASF could construct quasi-vertical fiber bridging,and it was used as"mechanical claws"to grasp adjacent fiber layers for creating a stronger mechanical interlocking,and this effectively improved resin-rich region and interfacial transition region at the interlayers.The simple and effective IT-MNASF interleaving technique was very successful in low-cost and high-strength development of BCFRP heterogeneous composites.

Tailoring micro/nano-fibers for biomedical applications

Nano/micro fibers have evoked much attention of scientists and have been researched as cutting edge and hotspot in the area of fiber science in recent years due to the rapid development of various advanced manufacturing technologies,and the appearance of fascinating and special functions and properties,such as the enhanced mechanical strength,high surface area to volume ratio and special functionalities shown in the surface,triggered by the nano or micro-scale dimensions.In addition,these outstanding and special characteristics of the nano/micro fibers impart fiber-based materials with wide applications,such as environmental engineering,electronic and biomedical fields.This review mainly focuses on the recent development in the various nano/micro fibers fabrication strategies and corresponding applications in the biomedical fields,including tissue engineering scaffolds,drug delivery,wound healing,and biosensors.Moreover,the challenges for the fabrications and applications and future perspectives are presented.

Temperature measurement based on radialization power for micro-hotplate

A novel method to measure the temperature on the surface of micro-hotplate was presented. The tiny fiber probe and the optical power meter were employed to measure the sample radialization power. By means of comparing the relationship between the radialization power and the temperature, sample surface temperature can be discerned accurately. Such an approach has provided more accuracy than traditional temperature measurements. The experimental result based on this method is quite similar to that of simulation by the finite element analysis (FEA) software of Ansys in theory. This measurement is very useful for measuring temperature for these micro samples prone to be untouchable.

Triple and Double Photons Absorption Process and Down-Conversion Laser Emitting Investigation of Er-Ion Doped Microsphere

We report a readily and cheap method to build taper optical fiber-Er3+ doped microsphere platform to investigate upconversion fluorescence emission and down-conversion laser oscillation with low threshold pump power. We demonstrate to dope Er3+ into silica microsphere surface by dipping a single-taper optical fiber into a certain concentration of erbium nitrate solution (Er(NO3)) , then dry it and use the electrical-arc of the optical fiber splicer to melt the tip of taper fiber to form the Er3+-doped silica microsphere due to surface tension induced. We also present a HF acid etching setup to fabricate low loss biconical optical taper fibers. We demonstrate the Er3+ doped silica microsphere triple photons and dual photons absorption process of up-conversion fluorescence emission and down-conversion laser oscillation spectra by using the optical tapered fiber to couple 976 nm/1534 nm pump light source.

医学领域微小力值传感测量技术的研究进展

针对医学领域科学研究、临床疾病的诊断与手术等对微小力值测量的迫切需求,对医学领域微小力值传感测量研究方向、进展及其应用情况进行了综述。首先,从医学领域微小力值测量的需求出发,分析了测量的特点与要求,介绍了电容式、电阻应变式和压电式等传统电学式微小力传感测量技术的国内外研究成果,分析了电学式测量方法的技术特点与不足;然后,系统地介绍了目前微小力值测量中广泛采用的光学式一维及多维传感测量技术,对基于光学相干层析成像(OCT)、法布里-珀罗干涉仪(FPI)、光纤布拉格光栅(FBG)、强度调制型光纤传感等的光学式微小力值传感测量原理、方法、技术特点进行了分析;最后,对国内外最新研究成果、发展水平及在医学领域的应用情况进行了分类整理和归纳评述,对不同测量原理与方法的技术特性、优缺点、适用测量范围与应用场景进行了系统性的对比分析。研究结果表明:当前医学领域微小力值传感测量存在的主要问题包括微小力值无法溯源、高精度宽量程测量需求无法满足,并且在多种参数的并行监测和同步测量、复合传感测量、集成光路式传感技术等方面有待进一步研究和探索。该综述可为后续医学领域微小力值传感测量研究方向与思路提供参考。

导电微纳纤维复合纱的制备及其气敏特性

为开发高质量的气敏传感器,利用水浴静电纺丝法制备以涤纶(PET)为芯纱,聚酰胺6(PA6)纳米纤维为包覆层的微纳纤维复合纱(MNY),基于原位聚合方法对MNY进行连续导电处理,制备微纳米纤维复合纱/聚苯胺(MNY/PANI)复合导电纱,以此作为气敏元件,同时将相同参数下制备的PET/PANI复合导电纱也作为气敏元件进行对照,探究不同结构纱线之间气敏效果的差异。研究结果表明:MNY具备良好的皮芯结构,经导电处理后MNY表面均匀分布了聚苯胺颗粒,MNY/PANI的电导率最高可达7.53 S/cm;相比于PET/PANI气敏元件,MNY/PANI气敏元件因其纳米结构的高比表面积对NH 3的灵敏度更高,能表现出更好的响应-恢复效果,重复性和稳定性更好,已初步具备了作为优良气敏元件的条件。

铁碳纤维纳米二氧化铈复合材料吸附As的性能与机理

采用铁掺杂微纳米纤维为基底,复合纳米二氧化铈制备了铁碳微纳米纤维@CeO_(2)材料复合材料,使用扫描电子显微镜(SEM),X射线衍射(XRD)和X射线光电子能谱(XPS)表征其微观形貌、物相组成,并对其废水中As的吸附性能与机理进行了研究.结果表明,铁的掺杂提高微纳米纤维的机械强度,并促进二氧化铈的分散负载.纳米CeO_(2)可均匀负载于微米铁碳纤维表面,形成二氧化铈高效裸露的连续界面,二氧化铈颗粒尺寸在6~9nm.在pH值为3~10的条件下,经过2h的吸附反应,初始浓度2mg/L的As,处理后浓度均在50μg/L以下,去除效率达98%以上.磷酸根共存会影响复合材料对As的吸附;多金属共存时,铁碳微纳米纤维@CeO_(2)材料对As表现出显著的吸附选择性.材料对As的吸附过程符合准二级动力学模型和Langmuir等温吸附模型,表明吸附过程以单分子层的化学吸附为主,饱和吸附容量49.02mg/g.以0.1mol/L的NaOH作为解吸液,经5次吸附-解吸循环后,废水中As的吸附效率仍在95%以上,表明该复合材料具有显著的循环稳定性.吸附机理研究表明,吸附主要通过材料表面形成的羟基基团与砷酸盐之间的配体交换.

基于边缘优化设计的低损耗Si3N4光功率分束器

随着信息技术的发展,市场对于更小型化、更高效光器件的需求不断增加.采用互补金属氧化物半导体(complementary metal oxide semiconductor,CMOS)工艺,成功制备了Si_(3)N_(4)光功率分束器并对其进行测试.结果表明,在1550 nm波长下,边缘优化的1×8功率分束器的总损耗仅为1.30 dB,且其体积相较于传统设计可减小30%.本研究应用逆向优化算法,突破了传统设计仅能针对规则图形设计的限制,为实现小尺寸、低损耗的光功率分束器提供了一种可行途径.

微纳层叠带状聚丙烯腈初生纤维的制备及性能研究

以聚丙烯腈(PAN)和二甲基亚砜(DMSO)为原料,采用新型微纳层叠挤出技术制备了微纳层叠带状聚丙烯腈(PAN)基初生纤维,利用扫描电子显微镜、X射线衍射仪、电子万能试验机对初生纤维的性能进行了研究。分析了纤维凝固成形过程中空气层高度、凝固浴温度、凝固浴浓度对微纳层叠带状PAN初生纤维性能的影响。结果表明:层叠带状PAN初生纤维相比于传统圆形截面纤维,在纺丝过程中能保持良好的带状截面不变形;并且在空气层高度为30mm,凝固浴温度为45℃,凝固浴浓度为40%工艺条件下制备的层叠带状PAN初生纤维综合性能较好,获得了结晶度为31.3%,晶粒尺寸为4.53nm,拉伸强度为14.60MPa的层叠带状PAN初生纤维。

基于纤维芯层流体力学方法制备聚合物功能微球研究进展

聚合物复合微球在医药、传感、光学、显示等领域,特别是在医药领域的临床诊断、病理成像和药物输送等方面具备重要应用价值。但是,聚合物复合微球的合成路线复杂、加工效率低下,常规工艺通常难以兼顾微球粒径单分散性、生产成本、产量等综合要求。近年来,纤维芯层流体力学方法依据纤维内发生的流体界面不稳定性(PRI)现象,可在微纳米尺度制备具有高度单分散性的聚合物微球,同时成本可控,适合批量生产。本文综述了流体界面不稳定性原理、纤维芯层PRI方法制备工艺、功能微球和结构微球的纤维芯层PRI方法制备等方面的最新进展,以及针对纤维芯层PRI方法的最新改进。

凝固浴牵伸对微纳层叠带状PAN原丝性能的影响

采用新型微纳层叠挤出技术制备了层叠带状聚丙烯腈(PAN)碳纤维原丝,利用扫描电子显微镜、X射线衍射仪、万能材料试验机和差示扫描量热仪对原丝的性能进行表征,研究了不同凝固浴牵伸倍数对微纳层叠带状PAN原丝截面形态、结晶性能、力学性能以及热行为的影响。研究结果表明,随着凝固浴牵伸倍数的提高,层叠带状PAN原丝的厚度显著减小,线密度显著降低;层叠带状PAN原丝的结晶度和拉伸强度随着牵伸倍数的提高呈现先增加后减小的趋势,凝固浴牵伸倍数为5.5倍时,获得的层叠带状PAN原丝的性能较好。当凝固浴牵伸倍数从5.5倍增加至6.5倍时,原丝的拉伸强度由26.08 MPa降低至23.36 MPa。实验结果表明,凝固浴牵伸倍数为5.5倍下制备的层叠带状PAN原丝具有较好的综合性能,其结晶度为39.1%,拉伸强度和拉伸模量分别为26.08及661 MPa。