Fiber System Research Articles

Retraction Note: Enhancing long-haul radio over fiber systems through chromatic dispersion mitigation using cascaded IDCF and apodized fiber bragg grating

Retraction Note: Enhancing long-haul radio over fiber systems through chromatic dispersion mitigation using cascaded IDCF and apodized fiber bragg grating

Electrospun fiber patches for inflammatory skin diseases – Correlating in vitro drug release with ex vivo permeation

In this proof-of-concept study, we aimed to develop an anti-inflammatory patch that in contrast to the semi-solid standard therapy is dry and non-greasy, and only needs to be changed once a day due to continuous release of the active ingredient over 24 h. While fiber materials for the treatment of inflammatory skin diseases have been reported in the literature, the majority of studies focuses solely on material characterization including in vitro release studies; however, there is a lack of ex vivo permeation studies as well as comparison with standard therapy. However, such experiments are crucial to deduct the potential efficacy of the drug delivery system, as skin absorption of the drug may be the rate-limiting step and not the drug release. Therefore, we set out to investigate different types of electrospun fiber systems based on polycaprolactone, a polymer with a well-established safety profile widely used for fabricating electrospun patches. The electrospun fiber patches were loaded with the anti-inflammatory drug hydrocortisone and characterized not only for their drug release properties, but for the first time also for their skin permeation and retention as well as their cytocompatibility and anti-inflammatory properties on human skin. While in the release studies, the layer-by-layer fiber system proved to be best suited for an application time of 24 h, this was not reflected in the permeation studies, where all fiber systems showed a similar skin permeation and retention of the drug. In our study set-up, a comparison with standard cream formulations revealed that electrospun fibers offer an advantage in terms of the permeated amount of hydrocortisone. Overall, this study supports the importance of conducting comparisons with standard therapies and, additionally, confirms that electrospun fibers are a promising dosage form for the controlled release of anti-inflammatory drugs for the treatment of inflammatory skin diseases.

The SDSS-V Local Volume Mapper (LVM): Scientific Motivation and Project Overview

We present the Sloan Digital Sky Survey V Local Volume Mapper (LVM). The LVM is an integral-field spectroscopic survey of the Milky Way, Magellanic Clouds, and a sample of local volume galaxies, connecting resolved parsec-scale individual sources of feedback to kiloparsec-scale ionized interstellar medium (ISM) properties. The 4 yr survey covers the southern Milky Way disk at spatial resolutions of 0.05–1 pc, the Magellanic Clouds at 10 pc resolution, and nearby large galaxies at larger scales totaling >4300 deg2 of sky and more than 55M spectra. It utilizes a new facility of alt–alt mounted siderostats feeding 16 cm refractive telescopes, lenslet-coupled fiber optics, and spectrographs covering 3600–9800 Å at R ∼ 4000. The ultra-wide-field integral-field unit has a diameter of 0.°5 with 1801 hexagonally packed fibers of 35.″3 apertures. The siderostats allow for a completely stationary fiber system, avoiding instability of the line-spread function seen in traditional fiber feeds. Scientifically, LVM resolves the regions where energy, momentum, and chemical elements are injected into the ISM at the scale of gas clouds, while simultaneously charting where energy is being dissipated (via cooling, shocks, turbulence, bulk flows, etc.) to global scales. This combined local and global view enables us to constrain physical processes regulating how stellar feedback operates and couples to galactic kinematics and disk-scale structures, such as the bar and spiral arms, as well as gas in- and outflows.

Multi-wavelength generation in UV and green bands through SRS and parametric processes in silica fibers.

We report on multi-wavelength generation through simultaneous second-order and third-order nonlinear parametric processes following cascaded stimulated Raman scattering (SRS) in silica fibers. The fiber system consists of a short standard step-index silica fiber and a microfiber tapered from it. When this system is pumped with a 130 ps laser at 1040 nm, multiple new wavelengths in the UV (340-370 nm) and green (507-547 nm) bands arise through four-wave mixing (FWM)/sum-frequency generation (SFG) from the pump and its Raman signals. The evolution of these wavelengths with pump power is demonstrated in detail. Matching of frequencies and propagation constants in the involved processes is verified. This work provides a compact and simple method of multi-wavelength generation with fibers.

Investigation of optical soliton solutions for the cubic-quartic derivative nonlinear Schrödinger equation using advanced integration techniques

This paper aims to investigate optical soliton solutions in the context of the cubic-quartic derivative nonlinear Schrödinger equation with differential group delay, incorporating perturbation terms for the first time. Motivated by the need to better understand soliton dynamics in advanced optical communication systems, we employ three integration techniques: the direct algebraic approach, Kudryashov’s method with an addendum, and the unified Riccati equation expansion method. Our study reveals that, by appropriately selecting parameter values, the resulting solutions include Jacobi elliptic functions that describe straddle solitons, bright, dark, and singular solitons. We also identify the conditions under which these soliton pulses can exist. Furthermore, we provide numerical simulations to illustrate these solutions under specific parameter settings, highlighting their potential applications in optical fiber systems.

Study of a Crosstalk Suppression Scheme Based on Double-Stage Semiconductor Optical Amplifiers

An all-optical crosstalk suppression scheme is desirable for wavelength and space division multiplexing optical networks by improving the performance of the corresponding nodes. We put forward a scheme comprising double-stage semiconductor optical amplifiers (SOAs) for wavelength-preserving crosstalk suppression. The wavelength position of the degenerate pump in the optical phase conjugation (OPC) is optimized for signal-to-crosstalk ratio (SXR) improvement. The crosstalk suppression performance of the double-stage SOA scheme for 20 Gb/s quadrature phase shift keying (QPSK) signals is investigated by means of simulations, including the input SXR range and the crosstalk wavelength deviation. For the case with identical-frequency crosstalk, the double-stage SOA scheme can achieve equivalent SXR improvement of 1.5 dB for an input SXR of 10 dB. Thus, the double-stage SOA scheme proposed here is more suitable for few-mode fiber systems and networks.

Development of an antioxidant and anti-lipid peroxidation film based on quercetin-loaded Eudragit EPO®/sodium hyaluronate electrospun fibers

This study focuses on the development of a film based on electrospun fibers for the encapsulation of quercetin, to be applied as an antiradical and anti-lipid peroxidation system. Electrospun nanofibers based on Eudragit EPO (Eud EPO) and sodium hyaluronate (SH) with diameters ranging between 600 and 800 nm, and with smooth and/or rough surfaces were developed. Quercetin was successfully incorporated to the electrospun fiber system (≈92.1 %). Surprisingly, the free nanofibers showed great antiradical, reducing, and lipid antiperoxidation capacities. These properties were enhanced with the incorporation of quercetin, generating an enhanced synergistic effect. A film based on electrospun nanofibers with excellent biological properties was created through a simple method. Diverse bioactive compounds may enhance such biological properties. This system would have great potential for application within the biomedical sector.

Static and cyclic behavior of high-performance concrete reinforced with hybrid steel fibers using notched and un-notched flexural specimen

In this paper, the static and cyclic behavior of high-performance concrete reinforced with hybrid steel fibers (HPFRCs) using notched and un-notched flexural specimen were experimentally studied. The term 'hybrid steel fibers' refers to using a combination of different steel fiber s in HPFRC mortar. Three HPFRC types, produced from an identical mortar, contained a same total fiber content of 2.0 vol% but different hybrid fiber systems as follows: 0.5, 1.0, 1.5 vol% long hooked fiber blended with 1.5, 1.0, 0.5 vol% short smooth, respectively. All flexural specimens were designed with a prism-shape having dimensions of 40 × 40 × 160 mm (width × depth × full length). Two specimen types were employed: un-notched and notched specimen with its depth of 5 mm at specimen bottom. The specimens were experimented under static and cyclic loading using a three-point bending test. Despite the lower peak static load, the notched specimen produced the higher flexural strength and critical stress intensity factor, regardless of the HPFRC types. Under cyclic loading, the number of cycles of the notched specimens showed lower than that of the un-notched specimens, for all the HPFRC types at same fatigue stress ratio. Besides, the higher static flexural strength seemed to produce the lower fatigue endurance limit, based on the proposed fatigue response curves built by regression technique.

Efficient Light Coupling and Propagation in Fiber Optic Systems

This study explores the propagation of light in optical fibers, focusing on the fundamental principles and practical implications for fiber optic technologies. By analyzing the wave equation, the research demonstrates that light propagates as cylindrical waves within the fiber, contrasting with spherical waves in free space. The study highlights the significance of Gaussian beams, particularly from helium-neon lasers, finding a beam waist radius of approximately 12.6 μm and its position about 1.25 μm from the focus. These parameters are critical for optimizing laser beam coupling into the fiber. The research also measures the light transit time through a 100-meter fiber, revealing a light speed of approximately 2×108 m/sec, which is influenced by the fiber's refractive index. Additionally, the relationship between diode laser output power and injection current was investigated, demonstrating a linear correlation crucial for practical applications. The findings emphasize the importance of accurate measurements and configuration in improving fiber optic communication and laser performance. This comprehensive analysis provides valuable insights into the design and optimization of optical fiber systems, contributing to advancements in communication and laser technologies.

Improving the Performance of Bidirectional Communication System Using Second-Order Raman Amplifiers

In order to achieve low-cost scalability, the same-wavelength bidirectional (SWB) fiber communication system is a better solution. We present a detailed investigation of the performance of the different orders Raman amplifiers in same-wavelength bidirectional fiber communication systems. We discuss how to suppress the main factor affecting system performance which is Rayleigh scattering noise (RSN). By using different Raman amplifiers to construct different quasi-lossless transmission, the performance changes in the same-wavelength bidirectional fiber optic communication system were studied. On this basis, multi-channel and same-wavelength single fiber bidirectional system experiments were conducted to compare the performance of second-order Raman systems and first-order Raman systems. The results indicate that the Rayleigh scattering suppression effect of second-order Raman systems is better, and compared to first-order Raman systems, the average signal-to-noise ratio (SNR) can be increased by 2.88 dB.

Fiber temperature sensor based on dual-wavelength emitting Mg0.388Al2.408O4: Mn2+/Mn4+ phosphors for real-time temperature monitoring

Single doped Mg0.388Al2O3.408O4 phosphor was prepared and multivalent Mn ion (Mn2+ and Mn4+) emission was achieved in a single host. The structure, morphology, and luminescence characteristics of Mn ions in Mg0.388Al2O3.408O4 were discussed in detail, especially the temperature dependent emission characteristics of Mn ions. Based on the fluorescence intensity ratio (FIR) of Mn2+versus Mn4+ and the decay lifetime of Mn4+ emission as the temperature readout, a dual-mode optical temperature-sensing mechanism was proposed and studied in the temperature range of 293–473 K. The maximum relative sensitivities (Sr) are derived as 2.83 % K−1 (at 373 K based on FIR) and 3.40 % K−1 (at 473 K based on decay lifetime), respectively. The temperature sensing characteristics of Mg0.388Al2.408O4: Mn2+/Mn4+ powders in a full fiber system were studied, which can provide thermal-sensitive emissions at dual-wavelengths for stable ratiometric temperature sensing with good precision and repeatability. The constructed all fiber temperature sensing system has been applied in the on-line monitoring of CPU temperature.

Strong dipole-dipole interactions via enhanced light-matter coupling in composite nanofiber waveguides

We study the interaction of emitters with a composite waveguide formed from two parallel optical nanofibers in regimes of experimental importance for atomic gases or solid-state emitters. Using the exact dyadic Green's function we comprehensively investigate the coupling efficiency and the fiber-induced Lamb shift accounting for variations in emitter positions and fiber configurations. This reveals coupling efficiencies and Purcell factors that are enhanced considerably beyond those using a single fiber waveguide, and robustness in the figures of merit. We finally investigate resonant dipole-dipole interactions and the generation of entanglement between two emitters mediated through the composite waveguide under excitation. We show that the concurrence can be enhanced for two fiber systems, such that entanglement may be present even in cases where it is zero for a single fiber. All-fiber systems are simple in construction and benefit from a wealth of existing telecommunications technologies, while enjoying strong couplings to emitters and offering interesting light-matter functionalities specific to slot waveguides. Published by the American Physical Society 2024

Fiber orientation and orientation factors in steel fiber‐reinforced concrete beams with hybrid fibers: A critical review

AbstractFiber orientation is of paramount importance for the design of fiber‐reinforced concrete (FRC) structural elements, because it markedly influences the postcracking properties of such material. For this reason, structural codes introduce orientation factors which aim to correlate the real mechanical properties of the structural element with the ones determined from standard beams. Although the need of considering fiber orientation in design codes is commonly accepted, the orientation factors are still based on a limited number of research studies, raising the need to better determine fiber orientation to improve the current standards and support the design process of FRC elements. In this research, a steel fiber‐reinforced concrete (SFRC) with a hybrid system of macro and microfibers is steered into a broad range of fiber orientations and cast into standard beams. Besides measuring the mechanical performance of these SFRC beams, three different methods for assessing fiber orientation are employed, namely electromagnetic induction, image analysis, and micro‐computed tomography. The comparison between the outcomes of the different methods provides detailed information about the accuracy and suitability of each method, considering the corresponding domain of applicability at structural level. Finally, a critical review of the most common 2D and 3D orientation parameters found in literature is performed, and the equations are adapted to account for the hybrid system of fibers.

Deformation processes of polymer composites with stress concentrators under different reinforcement schemes

This paper is dedicated to an experimental investigation of an effect of a stress concentrator orientation on a mechanical behavior of polymer composites with various reinforcement schemes. Composite specimens have been made of layered carbon fiber reinforced polymer (CFRP) with lay-up patterns of [±45]16 and [0/90]16. The stress concentrators have been cut in a form of a rectangle (with rounded corners) orientated at angles of 0°, 45°, and 90° to a loading axis. The novel data about the composite’s mechanical behavior has been obtained by the digital image correlation (DIC) method, the acoustic emission (AE) method and the optical microscopy. Quasistatic tests have been carried out taking into account recommendations of the ASTM D5766, ASTM D3039, ASTM D3518. The effect of the stress concentrator orientation on the composite’s strength has been evaluated. It has been found that the stress concentrator does not affect the strength of the composite with the [±45]16 lay-up pattern. This peculiarity has been explained by the absence of the layers preventing the fibers system turning in the direction of the load application. The DIC method has allowed to study the evolution of inhomogeneous strain fields on the specimens’ surfaces. Computational simulations have been carried out within the elasticity stage. The results have shown that the strain fields obtained by both the DIC method and the numerical simulation were similar for the composites with the [0/90]16 reinforcement pattern. However, significant differences have been found for the [±45]16 reinforcement pattern, which have been explained by the development of inelastic zones near the stress concentrator even if the elastic stage is realized at the macrolevel. The using of the AE method and the optical microscopy has allowed to reveal typical mechanisms of the structural damage and to study their occurrence during the tests. It has been concluded that the orientation of the stress concentrator significantly influences the deformation processes of the CFRP with various reinforcement patterns.

Long-term stability of squeezed light in a fiber-based system using automated alignment.

Providing a cloud service for optical quantum computing requires stabilizing the optical system for extended periods. It is advantageous to construct a fiber-based system, which does not require spatial alignment. However, fiber-based systems are instead subject to fiber-specific instabilities. For instance, there are phase drifts due to ambient temperature changes and external disturbances and polarization fluctuations due to the finite polarization extinction ratio of fiber components. Here, we report the success of measuring squeezed light with a fiber system for 24h. To do this, we introduce stabilization mechanics to suppress fluctuations in the fiber system and an integrated controller to automatically align the entire system. The squeezed light at a wavelength of 1545.3nm is measured every 2min, where automated alignments are inserted every 30min. The squeezing levels with an average of -4.42 dB are recorded with an extremely small standard deviation of 0.08 dB over 24h. With the technologies developed here, we can build complicated optical setups with the fiber-based system and operate them automatically for extended periods, which is promising for cloud service of quantum computation.

Electrospun Polymeric Fiber Systems Inoculated with Cyanoacrylate Tissue Adhesive: A Novel Hemostatic Alternative during Open Surgery.

Natural-based and synthetic tissue adhesives have attracted extensive attention in the last two decades for their ability to stabilize uncontrolled bleeding instances. However; these materials present several drawbacks during use that scientists have tried to minimize in order to optimize their usage. This study comprises the development of a novel wound dressing, combining the excellent properties of polylactic acid (PLA) non-woven textile, as substrate, obtained through electrospinning, and a cyanoacrylate-based (CA) tissue adhesive, for rapid hemostatic action. Thus, the fabrication of electrospun PLA membranes at three different PLA concentrations, the design and manufacturing of the support system and the production of surgical patches were carried out. SEM and FT-IR methods were employed for analyzing the morphology as well as the indicative markers for the shelf life evolution of the obtained patches. PLA fibers with well-defined structures and a mean diameter varying between 4.6 and 7.24 μm were obtained with the increase of the concentration of the PLA solutions. In vivo tests on a rat model as well as peeling tests for good patch adhesion on liver fragments harvested from the test animals, with a limit for the strength of the liver tissue of 1.5 N, were carried out. The devices exhibited excellent adhesion to the parenchymal tissue and a long enough shelf life to be used with success in surgical procedures, also facilitating prompt hemostatic action.

Rotation and Hα Emission in a Young SMC Cluster: A Spectroscopic View of NGC 330

We present an analysis of high-resolution optical spectra recorded for 30 stars of the split extended main-sequence turnoff of the young (∼40 Myr) Small Magellanic Cloud globular cluster NGC 330. Spectra were obtained with the Michigan/Magellan Fiber System and Magellan Inamori Kyocera Echelle spectrographs located on the Magellan-Clay 6.5 m telescope. These spectra revealed the presence of Be stars, occupying primarily the cool side of the split main sequence. Rotational velocity ( vsini ) measurements for most of the targets are consistent with the presence of two populations of stars in the cluster: one made up of rapidly rotating Be stars ( 〈vsini〉≈200 km s−1) and the other consisting of warmer stars with slower rotation ( 〈vsini〉≈50 km s−1). Core emission in the Hδ photospheric lines was observed for most of the Hα emitters. The shell parameter computed for the targets in our sample indicates that most of the observed stars should have inclinations below 75°. These results confirm the detection of Be stars obtained through photometry but also reveal the presence of narrow Hα and Hδ features for some targets that cannot be detected with low-resolution spectroscopy or photometry. Asymmetry variability of Hα line profiles on the timescales of a few years is also observed and could provide information on the geometry of the decretion disks. Observations revealed the presence of nebular Hα emission, strong enough in faint targets to compromise the extraction of spectra and to impact narrow-band photometry used to assess the presence of Hα emission.

Spectrum contrast enhancement of fiber fabry-perot sensor by coupling efficiency improvement

This paper investigates the impact of interface angles on the coupling efficiency of a fiber Fabry-Perot interferometer (FFPI) sensor using both simulation and experimental methods. The FFPI sensor, which consists of a single-mode fiber (SMF), hollow-core fiber (HCF), and diaphragm, has its coupling efficiency determined by the generalized scattering matrix of the cascaded fiber system. To obtain the interface angles of the FFPI sensor, a new on-line monitoring system is developed based on microscopic images of the FFPI cavity and an image processing algorithm using OpenCV. By combining the eigenmode expansion method (EME) model and the online interface angle measurement technique, the coupling efficiency and spectral contrast of the FFPI cavity are evaluated and improved. Additionally, the corresponding working point in the intensity demodulation based FFPI sensor can be quickly identified. Using this method, an FFPI sensor with a spectral contrast of over 35 dB is achieved, which is significantly higher than existing similar sensors, and its sensitivity also reaches 50.80 mV/MPa. This work also holds significance for controlling and enhancing the spectral characteristics of other cascaded fiber optic sensors.

Splicing Hollow-Core Fiber with Standard Glass-Core Fiber with Ultralow Back-Reflection and Low Coupling Loss.

A main, yet-unsolved challenge in splicing hollow-core fiber (HCF) into standard single-mode fiber (SMF) systems lies in managing the strong Fresnel back-reflection that occurs when the light travels from the empty core of the HCF into the glass core of the SMF or vice versa. This impacts the performance of fiber systems that combine SMFs and HCFs due to effects such as multipath interference. Here, we demonstrate a new technique that combines angle-cleaving the HCF, which reduces the back-reflection, with offset-splicing the mode-field adapter to the SMF, which compensates for the refraction at the glass-air interface, enabling us to achieve low coupling loss. We first analyze this novel configuration via simulations and show that it is possible to achieve a coupling loss that is comparable to a conventional flat-cleaved splice. Subsequently, we fabricate an SMF-HCF connection with a loss of 0.6 dB prior to arcing (1.2 dB after splicing) and ultralow back-reflection (-64 dB) by applying an optimized 4.5° angle and 5 μm offset. To the best of our knowledge, this is the first low-insertion-loss spliced SMF-HCF connection where a widely acceptable level of back-reflection of <-60 dB is achieved.

Electrode-dependent thermoelectric effect in ionic hydrogel fiber for self-powered sensing and low-grade heat harvesting

Ionic thermoelectric materials show great significance for wearable energy devices, owing to the capability of the conversion between thermal and electrical energy. The two-dimensional massive structure which is difficult to integrate with fabrics of ionic thermoelectric materials, however, prevent them from realizing their full potential when employed in wearable electronics. In this work, ionic thermoelectric 1D PAM/LiTFSI4 hydrogel fibers with high aspect ratio, inherent flexibility, conductivity, anti-freezing, self-adhesion and self-healing properties are constructed by free radical polymerization technology based on a template strategy, which contains a PAM polymer matrix and an LiTFSI conductive material. Based on thermal diffusion, owing to the ion size difference, the covalent cross-linked polymer network and the electrode-dependent effect promote rapid transport of the cations and boost ion concentration difference, resulting in a huge ionic Seebeck coefficient of 19.02 mV K−1. Meanwhile, embedding hydrogel fibers into the woven textile demonstrates a promising thermoelectric wristband with desirable human heat collection and electrical output capabilities. What’s more, thanks to the introduction of LiTFSI, the microstructure and molecular network system of hydrogel fibers are reshaped, which significantly improved the ionic conductivity of hydrogel fiber, and endowed them with anti-freezing, self-adhesion and self-healing properties. The PAM/LiTFSI4 hydrogel fiber also has excellent strain and temperature sensing properties, which enable a variety of human signal monitoring. Besides, the hydrogel fiber-based sensor can realize self-powered sensing by generating a thermovoltage. Thus, combining the merits of one-dimensional structure, superior thermoelectric performances, sensing at low temperature, excellent adhesion, self-healing and anti-freezing properties together, believing that the PAM/LiTFSI4 hydrogel fiber will render new numerous in human signal monitoring and low-grade heat harvesting applications like wearable electronics and wearable energy supply devices.