High-capacity Fiber Research Articles

Interface-reinforced high-capacity fiber cathode for wearable Li–S batteries

ABSTRACT Fiber-shaped Li–S batteries are attractive for constructing smart textiles as flexible power solutions due to their high theoretical specific capacity, flexibility and wearability. However, severe interfacial issues, such as the shuttle effect of polysulfides on the cathode side, lead to capacity decay and poor lifespan of the batteries. Herein, we report a fiber-shaped composite cathode with collaborative interface interactions to maintain electrode integrity and boost electrochemical performance. In this architecture, nanosulfur-polyvinylpyrrolidone (nanoS-PVP) particles are uniformly implanted into the few-layer Ti3C2Tx with outstanding electrical conductivity and then coated on aluminum (Al) fiber current collectors. Impressively, nanoS and soluble polysulfides are restricted to the cathode side via synergy physical confinement and chemical adsorption of Ti3C2Tx. The PVP chains on the surface of the nanoS prevent the sulfur from agglomeration and bridge the Ti3C2Tx by abundant hydrogen bonds. The enhanced interface endows the cathode with excellent mechanical flexibility, good adsorption of polysulfides and fast reaction kinetics. Consequently, the prepared Ti3C2Tx/nanoS-PVP@Al cathode exhibits excellent cycling performance (capacity retention of 92.8% after 1000 cycles at 1 C), high-rate capacity (556.2 mAh g−1 at 2.0 C) and high linear capacity (22.9 mAh m−1). Additionally, the fiber-shaped Li–S battery works effectively under deformation and high/low-temperature conditions. It can be integrated into the fabric to power light emitting diodes or charge a smartphone wirelessly.

Polymer Engineering Enables High Linear Capacity Fiber Electrodes by Microenvironment Regulation.

Unlike bulky and rigid traditional power systems, 1D fiber batteries possess appealing features such as flexibility and adaptability, which are promising for use in wearable electronic devices. However, the performance and energy density fiber batteries are limited by the contradiction between ionic transfer and robust structure of fiber electrodes. Herein, these problems are addressed via polymer engineering to regulate the microenvironment in electrodes, realizing high-linear-capacity thick fiber electrodes with excellent cycling performance. The porosity of the electrodes is regulated using polymer crosslink networks designed with various components, and lithium-ion transfer is optimized through ether-abundant polymer chains. Furthermore, reinforced covalent bonding with carbon nanotube networks is established based on the modified functional groups of polymer networks. The multiscale optimizations of the porous structure, ionic transportation, and covalent bonding network enhance the lithium-ion dynamics property and structural stability. Therefore, ultrahigh linear-capacity fiber electrodes (17.8mAh m-1) can be fabricated on a large scale and exhibit excellent stability (92.8% after 800 cycles), demonstrating obvious superiority among the reported fiber electrodes. Moreover, this study highlights the high effectiveness of polymer regulation in fiber electrodes and offers new avenues for designing next-generation wearable energy-storage systems.

Design of low crosstalk homogeneous multicore few mode fiber for future high-capacity optical transmission

Many researches are diligently striving to develop a multi-core optical fiber with minimal signal distortion and reduced issues. The current study proposed few designs for homogeneous multicore few mode fiber which is characterized by the combination of high index ring and trench. This study also added four air holes surrounding each core. We considered pure silica for both the outer clad and the inner clad of the fiber. To calculate the crosstalk, a two-core model was used and the mode coupling coefficient was determined using coupled-mode and couple-power theory. For the current work we considered only the fundamental mode (LP01) to compute the crosstalk between neighboring cores. The proposed structure was simulated using the wave optics module of COMSOL Multiphysics (Version 6.1), a well-known commercial software tool based on finite element method (FEM). MATLAB (Version R2018a) was used to calculate the mode coupling coefficient and crosstalk after extracting the mode field data from COMSOL. Obtained results revealed that the proposed structure can offer lower crosstalk which was attractive for future high-capacity fiber optic communication using multicore fiber technology.

Efficiently adding mode multiplexing for cost-effective, high-capacity fiber links

Efficiently adding mode multiplexing for cost-effective, high-capacity fiber links

A novel few-mode multi-core fiber with large effective mode area and low inter-core crosstalk

This paper proposes a novel 7-core 5-mode fiber with large mode area and low inter-core crosstalk(XT). The proposed optical fiber, by adopting a combination of air-trench structure and high-index ring, realizes large mode area and low XT. The numerical analyses reveal that the proposed fiber can stably transmit 5 LP modes in the C+L band; the effective mode area of each of the 5 LP modes is larger than 110 µm2; the XT of in each of the 5 LP modes is smaller than −79 dB/km; each mode has an effective refractive index difference bigger than 1.1 × 10−3. Therefore, a low XT result can still be achieved when the mode area is large. The proposed optical fiber may be well utilized to construct a high-capacity fiber optic transmission system.

Photonic circuits for laser stabilization with integrated ultra-high Q and Brillouin laser resonators

The integration of stabilized lasers, sources that generate spectrally pure light, will provide compact, low-cost solutions for applications including quantum information sciences, precision navigation and timing, metrology, and high-capacity fiber communications. We report a significant advancement in this field, demonstrating stabilization of an integrated waveguide Brillouin laser to an integrated waveguide reference cavity, where both resonators are fabricated using the same CMOS-compatible integration platform. We demonstrate reduction of the free running Brillouin laser linewidth to a 292 Hz integral linewidth and carrier stabilization to a 4.9 × 10−13 fractional frequency at 8 ms reaching the cavity-intrinsic thermorefractive noise limit for frequencies down to 80 Hz. We achieve this level of performance using a pair of 56.4 × 106 quality factor Si3N4 waveguide ring-resonators that reduce the high-frequency noise by the nonlinear Brillouin process and the low-frequency noise by Pound–Drever–Hall locking to the ultra-low loss resonator. These results represent an important step toward integrated stabilized lasers with reduced sensitivity to environmental disturbances for atomic, molecular, and optical physics (AMO), quantum information processing and sensing, and other precision scientific, sensing, and communications applications.

Modulation Method for High-Capacity Fibre Channel Switch and High-Speed Pulse Network Data

Fibre channel (FC) switches are widely used in storage area networks and avionics systems. In this work, the FC protocol, the switching structure and the scheduling algorithm of the FC switch are deeply studied, and a 48-port FC switch is completed on a single-chip field-programmable gate array (FPGA). In addition, an improved scheduling algorithm for Inter-System Link Protocol (iSLP) is proposed for the input and scheduling of optical fiber pulse network data. On this basis, the overall architecture of the FC switch is proposed, the x690tffg1158 FPGA chip is selected, and the FC port control module is designed, which is composed of the receiving controller, the interface state machine, the sending controller, and the flow control. The routing table lookup module of FC switch is designed, the unicast routing table format and multicast routing table format are proposed, and the corresponding unicast and multicast routing table lookup table module architectures are designed. Aiming at the characteristics of high reliability and low distortion in the transmission of high-speed pulse network signals by FC switches, the modulation and demodulation of Bias-T (BIAS-T) are redesigned. The experiment is implemented using Verilog hardware description language (HDL), and Modelsim 10.5 software is adopted to simulate each module of the switch. The switch adopts an 8×N switching structure, which can accurately perform word synchronization. After the link is initialized, the transceivers can send and receive data frames normally. The redesigned BIAS-T is applied to solve the instability of the end of the analog modulation method, and then realize the low distortion and data integrity of the high-speed pulse signal of the FC switch.

Generation of bound solitons in a mode- locked Tm-doped fiber laser based on a graded-index multimode fiber saturable absorber

In this work, we report on the experimental observations of bound solitons in a Tm-doped passively mode-locked fiber laser by using an all-fiber saturable absorber, structured by a stretched graded index multimode fiber. Stable out-of-phase soliton pairs are obtained, with a temporal separation of 4.36 ps between the two ∼1.88 ps pulses, while the central wavelength can be continuously tuned from 1959 nm to 1962 nm. Meanwhile, some different pulse separations from 16 ps to 18.02 ps of tightly bound soliton pairs have also been realized by cautiously adjusting the PC. The results are helpful for us to understand the nonlinear dynamics in fiber lasers and further explore high-capacity fiber communication.

Research on de-noising method of fiber grating multiplexing network based on LCEEMD-LWT

A de-noising algorithm combining local complementary ensemble empirical mode decomposition (LCEEMD) and lifting wavelet transform technology (LWT) is proposed to deal with the crosstalk noise buildup in high-capacity fiber grating multiplexing networks. Complementary ensemble empirical mode decomposition (CEEMD) serves for decompose this original spectral signal, and the normalization permutation en-tropy (NPE) is applied for identifying high-frequency nonlinear sequences in low-order intrinsic mode function to suppress the random noise. The filtering accuracy is improved by further decomposing the high-frequency intrinsic mode function with LWT. Finally, reconstruction of de-noised signal. The simulation results show that the LCEEMD-LWT method achieves better quality evaluation indexes than LCEEMD and EEMD-LWT when processing 1dBlow SNR spectral signal. To study the noise elimination capability of this devised method for nonlinear non-stationary semaphores, this de-trended fluctuation analysis (DFA) algorithm served for evaluating the results. It is indicted that this devised way has this highest fractal scaling index (2.114), which is better than other de-noising methods.

Universal optical network architecture for future wireless LANs [Invited

Ultra-high-capacity indoor wireless connectivity is considered a key technology enabler to support end-to-end delivery of new services in the beyond-5G and 6G era. With physical layer data rates well beyond 10 Gbps, optical wireless communication (OWC) technology is positioning itself as a prospective candidate to support these services. While OWC is capable of handling multi-gigabit data rates in the wireless domain, the underlying distribution network architecture is not designed to transport the projected high volumes of data as well as the expected added complexity of managing and coordinating multiple narrow beams, beamsteering, and femto cells. To future proof wireless local area networks (LANs) including those using the radio spectrum, we propose a universal network architecture that features centralized software/hardware resource pools as well as control and data plane separation in conjunction with virtualization support and a high-capacity fiber distribution network. Such an architecture has the potential to realize interoperability between existing and future high-capacity wireless LAN technologies such as Wi-Fi 6 and Wi-Fi in the 60 GHz range, as well as dynamic and flexible allocation of resources in response to changing user bandwidth demand. Our results demonstrate the benefits of the universal network architecture in supporting high throughput performance, low delay, and increased resiliency.

Research on the dispersion characteristics of silica-based ring-core photonic crystal fiber used to transmit orbital angular momentum modes

In this paper, based on the silica-based ring-core photonic crystal fiber (PCF) used to transmit orbital angular momentum (OAM) modes, the effects of central air hole and first-layer cladding air holes on the dispersion of ring-core PCF are analyzed. As a result, it is found that the sizes of air holes have a regular regulation effect on the dispersion of PCF. Furthermore, a ring-core PCF which can support 44 OAM modes in communication band is proposed. The characteristics of the designed ring-core PCF, such as number of supported modes, dispersion, nonlinear coefficient and confinement loss, are systematically analyzed by using the finite element method (FEM). In summary, the conclusion is of guiding significance for the design of silica-based ring-core PCF structures, and the designed ring-core PCF has potential applications in the high-capacity fiber communication.

Rolling out of fibre optic networks in intermediate versus urban areas: An exploratory spatial analysis in the Netherlands

Within the growing literature on broadband development, much research has focused on infrastructure competition and spatial effects driving investment incentives in broadband provision. However, less attention has been paid to the geographical factors explaining very high capacity fibre based network rollout. The purpose of this paper is to examine these geographical effects of rollout of these networks by utilizing basic data mining techniques in conjunction with exploratory spatial data analysis. In explaining the rollout of these networks, the paper derives from the literature a geographical model on broadband provision and examines it empirically by focusing on the spatial and temporal effects driving very high capacity fibre-based network development in the Netherlands. The paper confirms previous research on market uncertainty and the techno-economics of broadband development, but shows, in addition, that more specific factors related to local effects and demand uncertainty are vital in explaining the rollout of very high capacity fibre-based network.

422 Million intrinsic quality factor planar integrated all-waveguide resonator with sub-MHz linewidth

High quality-factor (Q) optical resonators are a key component for ultra-narrow linewidth lasers, frequency stabilization, precision spectroscopy and quantum applications. Integration in a photonic waveguide platform is key to reducing cost, size, power and sensitivity to environmental disturbances. However, to date, the Q of all-waveguide resonators has been relegated to below 260 Million. Here, we report a Si3N4 resonator with 422 Million intrinsic and 3.4 Billion absorption-limited Qs. The resonator has 453 kHz intrinsic, 906 kHz loaded, and 57 kHz absorption-limited linewidths and the corresponding 0.060 dB m−1 loss is the lowest reported to date for waveguides with deposited oxide upper cladding. These results are achieved through a careful reduction of scattering and absorption losses that we simulate, quantify and correlate to measurements. This advancement in waveguide resonator technology paves the way to all-waveguide Billion Q cavities for applications including nonlinear optics, atomic clocks, quantum photonics and high-capacity fiber communications.

Study and Analysis for the Choice of Optical Fiber in the Implementation of High-Capacity Backbones in Data Transmission

Fiber optic implementation projects for backbones today have become a necessity, where in many cases failures due to cable stress breaks have been reported. Due to this, it is necessary to carry out a study and analysis of the zone and area prior to implementation. In this research work, through a method based on theory and analysis, the geographical and climatological conditions where the optical fiber will be installed in the Lima region, Peru, will be evaluated, as well as the study of mechanical loads and electric fields associated with the installation of fiber optics on existing electrical network lines will also be carried out. The results of this study showed that for regional backbone projects in the city of Lima, Peru, the use of the type of optical fiber should be considered under the recommendation of the International Telecommunications Union (ITU) -T G.652.D All -Dielectric Self-Supporting (ADSS). The studies and results obtained in this research may also help the various companies in the sector, in future implementations of high-capacity fiber optic backbones in data transmission, to make the best decision on the type of cable and its recommended characteristics for the region.

A Fast Heuristic for Gateway Location in Wireless Backhaul of 5G Ultra-Dense Networks

In 5G ultra-dense networks, a distributed wireless backhaul is an attractive solution for forwarding traffic to the core. The macro-cell coverage area is divided into many small cells. A few of these cells are designated as gateways and are linked to the core by high-capacity fiber optic links. Each small cell is associated with one gateway and all small cells forward their traffic to their respective gateway through multi-hop mesh networks. We investigate the gateway location problem and show that finding near-optimal gateway locations improves the backhaul network capacity. An exact p-median integer linear program is formulated for comparison with our novel K-GA heuristic that combines a Genetic Algorithm (GA) with K-means clustering to find near-optimal gateway locations. We compare the performance of K-GA with six other approaches in terms of average number of hops and backhaul network capacity at different node densities through extensive Monte Carlo simulations. All approaches are tested in various user distribution scenarios, including uniform distribution, bivariate Gaussian distribution, and cluster distribution. In all cases, K-GA provides near-optimal results, achieving average number of hops and backhaul network capacity within 2% of optimal while saving an average of 95% of the execution time.

Comparison of headspace solid-phase microextraction high capacity fiber coatings based on dual mass spectrometric and broadband vacuum ultraviolet absorption detection for untargeted analysis of beer volatiles using gas chromatography

Despite the same basic ingredients used in brewing, there is a significant variation in beer styles. With the rapid increase in craft brewing, beer styles have become even more numerous and complex in the recent past. A GC-MS/VUV (post-column split for dual detection) instrument with headspace high capacity SPME was used to investigate 21 different beers which represent three beer styles - India pale ales, blondes, and hefeweizens. Since results from untargeted studies can be affected by the sorbent material used, the extraction performances of three high capacity SPME fibers, i.e., polydimethylsiloxane, polydimethylsiloxane/carbon wide range, and polydimethylsiloxane/carbon wide range/divinylbenzene, were evaluated. Good reproducibility (<10% RSD) was obtained for each high capacity fiber using both detectors. The tandem MS/VUV detection coupled with GC separation proved to be particularly valuable for compound identification, especially for isomers and compounds with similar structures. The evaluation of VUV detection for untargeted analysis led to similar performances as MS detection. Both the VUV and the MS were able to effectively differentiate between beer styles using principal component analysis. In addition, the use of 3 different statistical approaches, one-way ANOVA (p-value < 0.05), partial least square discriminant analysis, and random forest, universally identified 12 of the components most influential in distinguishing the three beer styles (e.g., β-myrcene, linalool, isopentyl acetate, 2,4-di-tert-butylphenol). This is the first reported evaluation of VUV detection and the first comparison of simultaneous VUV and MS detection for untargeted classification of complex mixtures using GC.

A design of nested photonic crystal fiber with low nonlinear and flat dispersion supporting 30+50 OAM modes

In this paper, a novel nested photonic crystal fiber (PCF) with two guided modes regions is proposed, which can support 80 orbital angular momentum (OAM) modes over C wavelength band. The characteristics of designed nested PCF are systematically analyzed by using the finite element method (FEM). The results show that the isolation is kept above 40dB, the crosstalk between different guided modes regions can be neglected, and the dispersion is relatively flat, the nonlinear coefficient is lower than 2.65km−1W−1. Additionally, the confinement loss and effective mode field area of the designed nested PCF are also analyzed. In summary, the designed nested PCF has potential applications in the high capacity fiber communication of mode division multiplexing (MDM).

A novel dual guided modes regions photonic crystal fiber with low crosstalk supporting 56 OAM modes and 4 LP modes

In this paper, a novel photonic crystal fiber (PCF) with dual guided modes regions is proposed, which can support 56 orbital angular momentum (OAM) modes and 4 linear polarization (LP) modes over S + C + L wavelength bands. The introduction of a low refractive index ring enables separation of the guided modes regions and makes the designed PCF easier to fabricate. The characteristics of designed PCF are systematically analyzed by using the finite element method (FEM). The results show that the crosstalk between channels can be ignored and the confinement loss is lower than 5 × 10−8dB/m. Furthermore, dispersion and purity are also analyzed. In summary, the designed PCF has potential applications in the high capacity fiber communication of space division multiplexing (SDM).

Design of a circular photonic crystal fiber with square air-holes for orbital angular momentum modes transmission

A new circular photonic crystal fiber (C-PCF) with square air -holes in the cladding is proposed, which can support much more orbital angular momentum (OAM) modes. To optimize the design, the dependence of the number of OAM modes on fiber structure parameters is investigated. The simulation results show that the designed C-PCF can support 46 OAM modes stably over 800 nm bandwidth from 1.2 μm to 2.0 μm. Furthermore, the proposed C-PCF exhibits excellent fiber features, such as large effective index differences (˃10−4) without doping, low confinement loss (lower than 10−9 dB/m), relatively flat dispersion and small nonlinear coefficient (less than 2.58 km−1 W−1) for all eigenmodes. The proposed C-PCF could be a well-promising OAM fiber for mode division multiplexing(MDM) in high capacity fiber communication systems.

SDN Enabled Restoration With Triggered Precomputation in Elastic Optical Inter-Datacenter Networks

Flexi-grid elastic optical networks (EONs) provide a promising infrastructure for meeting the high-bandwidth and low-latency requirements of interconnecting datacenters. Since failures of high-capacity fiber links prevent users from accessing cloud services and lead to large amounts of data loss, much recent research has focused on inter-datacenter network failure recovery. In this paper, we build upon software-defined networking (SDN) technology and develop a fast restoration strategy with triggered precomputation (FR-TP) that achieves fast failure recovery with minimal resource overhead. Our work makes several contributions. We extend the controller functionality and OpenFlow protocol for software-defined elastic optical inter-datacenter network architectures, so as to obtain the global network state information quickly and accurately. We then present the FR-TP strategy and an associated trigger mechanism to compute backup paths before a link failure occurs. Furthermore, to improve the efficiency of path computation and bandwidth resource assignment, we construct a layered auxiliary graph of spectrum window planes (SWP-LAG) using a residual capacity matrix to change dynamically the width of the spectrum window planes (SWPs) to satisfy different service requests. Simulation results demonstrate that, compared with existing restoration strategies, the proposed FR-TP strategy combined with SWP-LAG reduces the recovery time by up to 30.4% in the network topologies studied without increasing the blocking probability.