A Smart Graded-index Multimode Fiber Based Sensor Unit for Multi-parameter Sensing Applications

We demonstrate a smart optical fiber sensor unit to realize a multi-parameter sensing, including temperature, curvature and strain or displacement. The sensor unit is composed of a Bragg grating in graded-index multimode fiber and a Fizeau cavity.

Photoisomerization,assembling and fluorescence photoswitching behaviors of a water-soluble stiff-stilbene with cucurbit[7]uril

Photoresponsive supramolecular systems have merited extensive attention for their applications in materials science and life science.Here,we synthesized a water-soluble stiff-stilbene molecular photoswitch,exhibiting outstanding photoisomerization reaction between its(E)-and(Z)-configurations upon irradiation at distinct light.The photoswitch can assemble with cucurbit[7]uril(CB[7])to form a superior fluorescent supramolecular complex(compared to the only guest)with excellent water solubility,which manifested dramatic photoluminescence enhancement caused by restriction of intramolecular rotation and remained good photochromic characteristics.Furthermore,introduction of CB[7]influence photoreaction quantum yield(Φ)of the stiff-stilbene,leading to reduction ofΦ_(E→Z) and increase ofΦ_(Z→E) of the stiff-stilbene.Importantly,the photoadjustable supramolecular assembly can act as a fluorescence switch,and the phototunable guest further selectively modulate G-quadruplex structure of Tel22 upon light irradiation or with addition of CB[7].The study provides a new simple way for accurately regulating photochromic properties of molecular switches and developing smart materials with potential applications in controlled modulation of G-quadruplex,targeted biological imaging and so on.

In-Fiber Thermally Diffused Coupler and Fiber Bragg Grating Inscribed in Twin-Core Fiber for Sensitivity-Enhanced Vector Bending Sensing

A vector bending fiber sensor based on core-by-core inscribed fiber Bragg gratings in a twin-core fiber has been proposed and experimentally demonstrated.An in-fiber integrated vector bending sensor is realized by using the thermal diffusion technique to fabricate the coupler.The characteristics of the coupler fabricated by thermal diffusion are simulated and experimented.By inscribing fiber Bragg gratings with different reflection wavelengths in the two cores of a symmetrical twin-core fiber,the curvature sensitivity can be enhanced by tracking the wavelength difference between the fiber Bragg gratings of the two cores.The measured bending sensitivity of the fiber Bragg grating ranges from–161.6 pm/m^(−1) to+165.5 pm/m^(−1).The differential sensitivity of the two cores is twice that of a conventional single grating,and the temperature-induced crosstalk is also reduced.The bending sensor proposed in this paper has the advantages of high integration,enhancing the sensitivity and two-dimensional orientation recognizability,and reducing temperature crosstalk,which can be a promising candidate for structural health monitoring or wearable artificial electronics applications.

Loop Topology Based White Light Interferometric Fiber Optic Sensor Network for Application of Perimeter Security

环拓扑学基于白轻 interferometric 传感器网络因为周界安全被设计了并且示威。在在纤维传感器在推迟的电缆线被包装或埋葬了电缆线的地方，察觉到系统的周界安全，一个双向光路径讯问者被使用米切尔森或 Mach-Zehnder 干涉仪造。这种技术的实际实现被使用放大自发的排出物(ASE ) 介绍点亮来源和标准单个模式纤维，它在通讯工业是普通的。传感器环拓扑学是完全被动的，绝对长度大小能为每个察觉到的纤维片断被获得以便测量伪分发紧张不安能被用来。为监视的长距离周界，这种技术不仅扩大 multiplexing 潜力，而且为察觉到的系统提供冗余性。因为就算嵌入的传感器环在某处碎，察觉到的系统将仍然工作，一个故障点在传感器环被允许。

Embedded whispering-gallery mode microsphere resonator in a tapered hollow annular core fiber

We propose and demonstrate a tapered hollow annular core fiber (HACF) coupler for excitation of whisperinggallery modes (WGMs) of an embedded microsphere resonator. The coupler is simply fabricated by fusion splicing of a segment of HACF with the single-mode fiber (SMF), and then improved by tapering the splicing joint to reduce the cone-apex angle. Therefore, the coupling efficiency from the SMF to the HACF is enhanced to excite various WGMs via evanescent field coupling. Normal positive, negative symmetrical Lorentzian and asymmetric Fano line shapes can be obtained by varying the resonator size and location. Another interesting phenomenon is observed that a higher Q-factor mode in a lower Q-factor mode has a contrast as high as 58. Temperature sensing with good stability is also demonstrated. This embedded WGM microsphere resonator in the tapered HACF is expected to promote environmental adaptability in practical applications due to its simplicity and

Recent Progress of In-Fiber Integrated Interferometers

A brief review of recent progress made in a range of in-fiber integrated interferometers for measuring is presented,with particular attention paid to the multi-core based in-fiber integrated techniques,which have the potential to be exploited in a variety of wide applications.

Simultaneous evaluation of two branches of a multifunctional integrated optic chip with an ultra-simple dual-channel configuration

We propose an ultra-simple dual-channel configuration for simultaneously evaluating two branches of a multifunctional integrated optic chip(MFIOC). In the configuration, the MFIOC is employed as a beam splitter to construct the demodulation interferometer together with a 2 × 2 fiber coupler. Interference happens between polarization modes traveling through different channels of the MFIOC. The cross-couplings of each channel are respectively characterized by the interference peaks which distribute on opposite sides of the central interference peak. Temperature responses of the MFIOC are experimentally measured from-40°C to 80°C. Results show that the proposed configuration can achieve simultaneous dual-channel transient measurements with resolution of-90 d B and dynamic range of 90 d B. In addition, the two channels of the configuration have consistent measuring performance, and the two branches of the MFIOC have different responses to temperature variation.

Optical-fiber-based powerful tools for living cell manipulation [Invited]

By using a specialty optical fiber, a series of powerful microparticle manipulation tools, including optical tweezers, a micro-optical hand, and an optical gun, are developed and demonstrated. In this paper,a review of our research activities on the optical manipulation of microparticles is presented. In particular,we will describe a kind of specialty optical fiber designed and fabricated for building optical trapping and manipulating tools. The performances of annular core fiber-based optical tweezers, a multicore fiber-based micro-optical hand, and a coaxial dual waveguide fiber-based optical gun are demonstrated as examples of applications and discussed in detail. The fiber can be used in cell manipulation in life science and drug response in medicine.

Review of Optical Fiber Sensor Network Technology Based on White Light Interferometry

Optical fiber sensor networks(OFSNs)provide powerful tools for large-scale buildings or long-distance sensing,and they can realize distributed or quasi-distributed measurement of temperature,strain,and other physical quantities.This article provides some optical fiber sensor network technologies based on the white light interference technology.We discuss the key issues in the fiber white light interference network,including the topology structure of white light interferometric fiber sensor network,the node connection components,and evaluation of the maximum number of sensors in the network.A final comment about further development prospects of fiber sensor network is presented.

Intelligent all-fiber device: storage and logic computing

The typical functions of the optical fiber are communication and sensing. However, the fiber functions need to extend to meet the requirements of the development of artificial intelligence. This paper achieves an all-fiber device with storage and logic computing functions using a single-mode fiber and Ge_(2)Sb_(2)Te_(5)(GST) material.We use the pulse amplitude modulation(the switching energy is about 50 nJ) to switch the GST state for performing the eight-level data storage(3-bit). The all-fiber memory device has the advantages of high optical contrast(about 38%), good reversibility, and high repeatability. We implement the all-optical logic operations(“AND”and “OR”) by using two memory cells in series and parallel. For the first time, we use the single-mode optical fiber to realize storage and computing functions, and this intelligent fiber has tremendous application potential in intelligent optical fiber communication and portends a new paradigm for brain-like computing.

Tunable fiber-tip lens based on thermo-optic effect of amorphous silicon

We theoretically demonstrate a compact all-dielectric metasurface fiber-tip lens composed of sub-wavelength amorphous silicon on the end face of a multimode fiber.The full 2πphase control was realized by varying the widths of resonant units.The tunable focal length is achieved by using the thermal-optic effect of amorphous silicon.The focal length increases from 309μm to 407μm when the temperature changes by 300 K.The temperature controlled all-fiber integrated lens is compact and with high efficiency and provides an excellent platform of a fiber-tip lab.Meanwhile,the proposed fiber lens does not have any structural changes during dynamic tuning,which improves the durability and repeatability of the devices.

Laser-induced rotary micromotor with high energy conversion efficiency

Light is a precious resource that nature has given to human beings.Converting green,recyclable light energy into the mechanical energy of a micromotor is undoubtedly an exciting challenge.However,the performance of current light-induced micromotor devices is unsatisfactory,as the light-to-work conversion efficiency is only10-15–10-12.In this paper,we propose and demonstrate a laser-induced rotary micromotor operated byΔα-type photopheresis in pure liquid glycerol,whose energy conversion ratio reaches as high as 10-9,which is 3–6 orders of magnitude higher than that of previous light-induced micromotor devices.In addition,we operate the micromotor neither with a light field carrying angular momentum nor with a rotor with a special rotating symmetrical shape.We just employ an annular-core fiber to configure a conical-shaped light field and select a piece of graphite sheet(with an irregular shape)as the micro-rotor.TheΔα-type photophoretic force introduced by the conicalshaped light field drives the rotation of the graphite sheet.We achieve a rotation rate up to 818.2 r/min,which can be controlled by tuning the incident laser power.This optical rotary micromotor is available for twisting macromolecules or generating vortex and shear force in a medium at the nanoscale.