Poly Fiber Research Articles

High-performance dual-core conjoined tube negative curvature fiber polarization beam splitter

High-performance dual-core conjoined tube negative curvature fiber polarization beam splitter

Broadband and tunable fiber polarizer based on a graphene photonic crystal fiber.

The recent flourishing development of two-dimensional (2D) graphene has sparked considerable interest and extensive research on graphene-based optical fiber polarizers. However, studies on graphene-optical fiber polarizers focused on the structure with graphene films attached to side-polished fibers, which face challenges such as low birefringence of 10-6, low polarization extinction ratio (PER), and narrow polarizing window of tens of nanometers. Here, a fiber polarizer based on a graphene-photonic crystal fiber (Gr-PCF) is proposed firstly, which exhibits high birefringence of ∼2.5 × 10-3, high PER of ∼111 dB/mm, broad polarizing window of >400 nm, and tunable polarization states. Graphene or graphene/hBN/graphene (Gr/hBN/Gr) heterojunctions are attached to the surface of two square holes in the PCF to make one of the polarizing modes attenuate significantly. The tunability of the Fermi level (EF) in Gr/hBN/Gr enables the proposed device to function as a polarizer or a polarization-maintaining fiber. The combination of PCF's endless single-mode feature and graphene's broadband optical response feature enables the fiber polarizer to exhibit a wide spectrum range with single-mode transmission characteristics.

EVALUATION OF PROPERTIES OF WOOD PLASTIC COMPOSITES MADE FROM SEVEN TYPES OF LIGNOCELLULOSIC FIBERS

This article aims to investigate the characteristics of wood plastic composites (WPC) prepared from polyethylene (PE) reinforced with lignocellulosic fibers derived from the xylem and bark of Masson pine, fir, cypress, as well as from Moso bamboo. The surface polarity and elemental composition of fibers were determined through contact angle measurements and X-ray photoelectron spectroscopy (XPS). The lignocellulosic fiber/PE composites were manufactured through hot-pressing technique, and their water absorption, mechanical properties, and mildew resistance were evaluated. The results revealed that the surface free energy of xylem fibers was higher than that of bark fibers among the three conifer species. XPS analysis showed that the O/C ratio of bark was consistently lower than that of xylem fiber. Among the three conifers, the Masson pine bark had the lowest O/C ratio (22.25%), while its xylem fibers had the highest ratio of 41.64%. WPC made with bark fibers had better water resistance. Additionally, the composites reinforced with xylem fibers showed superior static bending strength, impact strength, and mildew-resistant properties as compared to the composites reinforced with bark fibers. WPC made from bamboo fibers exhibited the best water resistance, with a water absorption rate and thickness swelling rate of 1.83% and 1.42%, respectively. They also had the highest static bending strength, elastic modulus, and impact strength, at 41.31 MPa, 3.82 GPa, and 10.24 kJ/m2, respectively. The WPC made from fir xylem fibers showed the most effective mildew resistance, with the smallest damage (0.50).

Optimizing and Predicting Performance of Dual-Side Polished SPR Photonic Crystal Fiber using MLR and ANN Models

Optimizing and Predicting Performance of Dual-Side Polished SPR Photonic Crystal Fiber using MLR and ANN Models

Dual-window polarization filtering characteristics of rectangular photonic crystal fibers

This paper presents a photonic crystal fiber (PCF) polarization filter with a square array arrangement of gold film fillings, allowing for filtering at dual wavelengths. The paper analyzes the dispersion characteristics and loss properties of this structure and optimizes the structural parameters through adjustments to achieve the best performance. At 1310 nm, the confinement losses of x and y polarization fundamental modes are 903.54 dB/cm and 30.51 dB/cm, respectively; at 1640 nm, the confinement losses of y and x polarization fundamental modes are 479.02 dB/cm and 88.72 dB/cm, respectively. The corresponding filtering bandwidths are 390 and 350 nm, while the full width half maximum (FWHM) is 59.56 nm, indicating excellent selectivity and resolution of the filter. The performance metrics, such as confinement loss, extinction ratios, and bandwidth, are compared in the paper with those reported for other filters. Additionally, the study also analyzed the filter’s performance under varying manufacturing tolerances of gold film thickness and air hole diameter by 5%, revealing that the filter’s performance remains stable and feasible even in the presence of errors.

Enhancing the performance of electrorheological fluids by structure design

By incorporating polar fibers into the design of electrorheological (ER) fluids, a 130% performance improvement can be achieved with the addition of only 0.8 vol% of polar long fibers. We quantitatively analyzed the impact of relatively long fibers on improving ER performance by measuring the yield stress, shear stress, and current density after adding fibers. Both optical microscopy and transmission electron microscopy were used to observe and analyze the interaction between ER particles and polar fibers. The results indicate that, under the influence of an electric field, the fibers transform the one-dimensional chain-like structure into a two-dimensional mesh structure, greatly improving the ER performance. The transformation of structure induced by the polar fibers in the ER fluids amplifies the ER effect. However, the inclusion of non-polar fibers does not contribute to this enhancement, as a point of comparison. Moreover, to ensure the universality of this method, we used two different types of ER fluids in experiments. The utilization of this method offers a straightforward, environmentally friendly, and highly effective approach. Furthermore, this study provides a novel technical solution aimed at enhancing the performance of ER fluids.

Tunable chalcogenide solid-core anti-resonant fiber polarization filter based on SPR effect

Based on surface plasmon resonance (SPR), we proposed a tunable chalcogenide solid-core anti-resonant fiber (SC-ARF) polarization filter. The purpose of introducing the SPR, which is excited by coating the inner wall of the cladding tubes with a gold film, is to achieve a discrepancy between the confinement loss of two polarized fundamental modes (FMs). The full-vector finite element method (FV-FEM) evaluates the impact of fiber core radius, cladding tube radius, cladding tube wall thickness, and gold film thickness on the polarization filter characteristics. The results show that when the thickness of the gold film is 30 nm and the fiber length is 4 mm, the filter bandwidth can simultaneously cover the S + C + L optical communication band and reach 248 nm, and the extinction ratio (ER) value reaches -377.46 dB. Moreover, we also confirmed the tuning effect of the gold-coated cladding tube wall thickness on the resonance wavelength. The proposed fiber polarization filter has potential application value in optical fiber communication and transmission.

Intrinsic influence of the stress on the optical properties of Panda-type erbium-doped fibers

In this study, erbium-doped fiber (EDF) and Panda-type polarization maintaining erbium-doped fiber (PM-EDF) were fabricated from the same erbium-doped preform. The intrinsic influence of stress induced by the Panda-type design on the optical properties was investigated. A local structural model of EDF was developed to simulate the introduction of stress by varying the length of non-bridging oxygen (NBO) bonds between erbium ions (Er3+) and the silica network, providing theoretical insights. An increase in bond length (indicative of tensile stress), results in decreased excitation and emission intensities for EDF, and the peaks exhibit redshifts. Conversely, a decrease in bond length (indicative of compressive stress), leads to increased excitation and emission intensities, with the peaks showing blueshifts. Experimentally, PM-EDF demonstrated a lower absorption coefficient compared to EDF, with absorption peaks experiencing redshifts of approximately 2 nm. Furthermore, the emission intensity was diminished, and the emission peak at 1530 nm displayed a redshift of around 3 nm. The fluorescence lifetime was shortened to 9.99 ms. Additionally, the total gain of PM-EDF decreased by approximately 4 dB, and the bandwidth narrowed by roughly 13%. The experimental outcomes largely align with the simulation predictions, further corroborating the significant impact of stress on the optical properties of PM-EDF.

Electric-field activating on-surface tailored (OST) coarse polyester fibers for efficient airborne particle removal: Interfacial morphologies and electrical response

Fibrous filtration is the most-used method for indoor particulate matter (PM) removal. The filtration performances are governed by filters’ intrinsic geometries, displaying the tradeoff among efficiency, resistance, and lifespan. In this contribution, we provided a chemically-synthesized strategy to improve the performance of coarse filters while preserving their ultralow initial resistances. After elucidating PM-fiber interactions, the fibrous interfacial nano-morphologies were tailored by different dielectric coatings based on commercially-available substrates. Activated by fiber polarizing, the tuned morphologies with ∼100 nm surface roughness and enhanced electrostatic potential are considered the drivers of boosted filtration efficiency. In practice, a 10-mm-thick polydopamine (PDA)-MnOx coated polyester filter possessed an improved efficiency of 97.7 % for 300–500 nm particles, and the ultralow resistance of 11.2 Pa at 0.5 m/s filtration velocity. The strong surface adhesion facilitated long-term efficiency of 95.6 % in a continuous 25-day period without any decay. The nanoscale coatings, which were just one-thousandth in thickness of the fiber gaps, enabled more than 50-fold improvement of the filters’ quality factor. We further established dimensionless factors to evaluate the cost-performance effect. We expect the strategy and techniques can pave the way to better understand electrostatic air filtration, being competitive candidates in the air filtration community.

Dual-Core Photonic Crystal Fiber Polarization Beam Splitter Based on a Nematic Liquid Crystal with an Ultra-Short Length and Ultra-Wide Bandwidth

This paper presents a novel pentagonal structure dual-core photonic crystal fiber polarizing beam splitter (PS-DC-PCF PBS) filled with a nematic liquid crystal (NLC) in the central hole. Unlike previous designs with symmetric arrangements, the upper and lower halves of the structure have different air hole arrangements. The upper half consists of air holes arranged in a regular quadrilateral pattern, while the lower half features a regular hexagonal arrangement of air holes. By filling the central hole with birefringent liquid crystal, the birefringence of the structure is enhanced, reducing the coupling lengths along the x polarization and y polarization directions. The polarization properties, coupling characteristics, and the influence of different structural parameters on the extinction ratio of the polarizing beam splitter are analyzed using the full-vector finite element method. Simulation results demonstrate that the designed PS-DC-PCF PBS achieves a maximum extinction ratio (ER) of 72.94 dB with a splitting length of only 61.9 μm and a wide operating bandwidth of 423 nm (1.324–1.747 μm), covering most of the O, E, S, C, L, and U communication bands. It exhibits not only ultra-short splitting lengths and ultra-wide splitting bandwidth but also good manufacturing tolerances and anti-interference capabilities. The designed PS-DC-PCF PBS could provide crucial device support for future all-optical communication systems and has potential applications in fiber optic communication or fiber laser systems.

Analysis and Stability Study of Isoeugenol in Aquaculture Products by Headspace Solid-Phase Microextraction Coupled to Gas Chromatography-Mass Spectrometry.

Headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME-GC-MS) offers an alternative analysis method for isoeugenol (an active ingredient in fish sedatives) that avoids the use of organic solvents, simplifies sample preparation, and can be fully automated. This work focuses on developing and evaluating an HS-SPME-GC-MS method for isoeugenol in aquaculture samples and testing the stability of isoeugenol itself. Because of isoeugenol's relatively low volatility, more polar SPME fiber coatings (polyacrylate and polydimethylsiloxane/divinylbenzene) had better performance and the headspace extractions took over 30 min to reach equilibrium. Additionally, it was found that isoeugenol was relatively unstable compared to a deuterated standard (d3-eugenol) in the presence of water. To address this, after the fish samples were homogenized with water, they were heated at 50 °C for 1 h prior to analysis for equilibration. By using the method developed in this work, isoeugenol's detection limits in multiple aquaculture matrices (shrimp, tilapia, and salmon) were in the low ng/g range (<15 ng/g), well below the target testing level (200 ng/g). Additionally, by adding d3-eugenol as an internal standard, excellent linearity (R2 > 0.98), accuracy (97-99% recoveries), and precision (5-13% RSDs) were all achieved.

Negative curvature fiber (NCF) polarization filter with large polarization loss ratio and ultralow loss in the terahertz range

A high-performance polarization filter based on the negative curvature fiber (NCF) with an asymmetric cladding structure is proposed and analyzed. The resonant effects of the x-polarization fundamental mode (XPFM) of the NCF are enhanced by the single-layer semi-elliptical tubes with a gradient wall thickness in the x-axis direction, while the anti-resonant effects of the y-polarization fundamental mode (YPFM) are strengthened by the nested double-layer elliptical tubes in the y-axis direction. The optimized structure shows a polarization loss ratio of greater than 100 in the range of 0.98–1.02 THz in addition to propagation losses of 0.94 dB/m and 7.43 × 10−4 dB/m at 1 THz for XPFM and YPFM, respectively. A polarization loss ratio of 1,276 is achieved and the polarization loss ratio is 6,321 at 0.98 THz. Our results show that the NCF polarization filter delivers better performance than recently reported filters in the terahertz band and the results reveal a new strategy to design high-performance polarization filters.

Highly-Sensitive Polymer Optical Fiber SPR Sensor for Fast Immunoassay

A new type of human immunoglobulin G (IgG) sensors based on the surface plasmon resonance (SPR) in the low refractive index (RI) plastic optical fiber (POF) and an antibody immobilization method is presented. A 50-nm-thick gold film was formed on the polished D-shaped fiber surface by magnetron sputtering. The RI response of the POF sensor is 30 049.61 nm/RIU, which is 26.5 times higher than that of single mode fiber (SMF) SPR sensors. The proposed SPR biosensor can be developed by simple and rapid modification of the gold film with 11-mercapto undecanoic acid (MUA). Upon immobilization of the goat anti-human IgG antibody, the resonance wavelength shifts by 11.2 nm. The sensor can be used to specifically detect and quantify the human IgG at concentrations down to 245.4 ng/mL with the sensitivity of 1.327 7 nm per µg/mL, which offers an enhancement of 12.5-fold compared to that of the conventional SMF based SPR sensors. The proposed device may find the potential applications in the case of use at the point of care.

Magnetic-fluid-infiltrated bilaterally polished photonic crystal fiber with butterfly core for LSPR based magnetic field sensing via water based Fe3O4 magnetic fluid

In this manuscript, a sensor is devised employing photonic crystal fiber with localized surface plasmon resonance (PCF-LSPR), emphasizing the manipulation of refractive index (RI) through magnetic fluid (MF). The sensor's air holes adopt a hexagonal arrangement, forming a butterfly core design, and the transmission channels for the effective confinement of optical field energy relies significantly on the regions surrounding the central air hole in both directions. MF serves as the sensing medium, and the top and bottom polished surfaces are coated with gold and titanium dioxide. The sensor undergoes analysis using the finite element method, scrutinizing its model characteristics, structural parameters, and sensing performance. The results indicate a wavelength sensitivity of up to 45,600 nm/RIU and a maximum figure of merit (FOM) of 434 RIU−1. Within the range of magnetic field 30–150 Oe, the highest magnetic field sensitivity records 3350 pm/Oe. Over the temperature range of 27.4–114 °C, the temperature sensitivity measures only 310 pm/°C. A maximum sensor resolution of 2.19×10−6RIU is achieved for x−pol. The linear relationship between the resonant wavelength and the magnetic field yields R2=0.9945, for degree (2) for x−pol. The proposed sensor exhibits notable advantages, including a structure which is very stable, high sensitivity, ease of integration, and resilience to electromagnetic interference. Additionally, it excels in detecting weak magnetic fields. Its potential applications span from industrial production, military technology, to medical equipment.

Spider silk biological material for Q-switched temperature sensor

Abstract A temperature sensor using compact design and highly sensitivity of side polished fiber and fiber Bragg grating as the sensing elements, Q-switched pulse fiber laser source with spider silk as a saturable absorber is proposed and demonstrated. Spider silk sample was gently collected from a live spider, specifically, the jumping spider of Plexippus sp. which then incorporated within the laser cavity by deposited the silk onto the surface of the fiber ferrule to facilitate the generation of Q-switched pulse fiber laser. The temperature variations were detected by monitoring the pulse train and radio frequency shift from the oscilloscope. The performance of the side polished fiber sensor probe shows a sensitivity of 0.1522 kHz/°C, with 0.9479 coefficient of determination value as the temperature increased from -0.5 °C to +3.1 °C. Besides, a linear temperature re-sponse in the range of 25 °C – 55 °C with a sensitivity of 0.0423 kHz/°C, and a linear correlation coefficient of 0.951 was experimentally achieved for a fiber Bragg grating device. The spider silk as a saturable absorber material is compatible with fiber optic interconnection and the temperature sensing characteristics were successfully demonstrated. The sensor's straight-forward design further enhances its desirability as a sensor for temperature monitoring, including in the field of biological treatments, consumer electronics, detection of chemical analytes, and medical diagnosis.

Modulation Format Identification Based on Multi-Dimensional Amplitude Features for Elastic Optical Networks

A modulation format identification (MFI) scheme based on multi-dimensional amplitude features is proposed for elastic optical networks. According to the multi-dimensional amplitude features, incoming polarization division multiplexed (PDM) signals can be identified as QPSK, 8QAM, 16QAM, 32QAM, 64QAM and 128QAM signals using the k-nearest neighbors (KNNs) algorithm in the digital coherent receivers. The proposed scheme does not require any prior training or optical signal-to-noise ratio (OSNR) information. The performance of the proposed MFI scheme is verified based on numerical simulations with 28GBaud PDM-QPSK/-8QAM/-16QAM/-32QAM/-64QAM/-128QAM signals. The results show that the proposed scheme can achieve 100% of the correct MFI rate for all six modulation formats when the OSNR values are greater than their thresholds corresponding to the 20% forward error correction (FEC) related to a BER of 2.4 × 10−2. Meanwhile, the effects of residual chromatic dispersion, polarization mode dispersion and fiber nonlinearities on the proposed scheme are also explored. Finally, the computational complexity of the proposed scheme is analyzed, which is compared with relevant MFI schemes. The work indicates that the proposed technique could be regarded as a good candidate for identifying modulation formats up to 128QAM.

Influence of cladding tube structure on transmission characteristics of negative curvature terahertz fiber

A novel type of polarization negative curvature terahertz fiber has been designed, which has a cladding region composed of two long semi-circular cladding tubes in the horizontal direction and four long semi-elliptical cladding tubes in the oblique direction. The optimal fiber dimensions are determined to investigate the internal relationship between polarization characteristics and fiber cladding structure. The transmission performances of the negative curvature fiber are investigated by varying the thickness of fiber cladding tubes and adjusting the structural characteristics of cladding tubes in different directions. Relatively good transmission performances can be obtained with a cladding tube thickness of 80 μm. The birefringence can be stably maintained at the order of 10−4, and the confinement loss of the x-polarized mode at 2.55 THz is 0.036 dB cm−1. Moreover, the dispersion coefficient of the two polarized modes is stable between ±0.6 ps (THz·cm)−1 in the 2.3–2.6 THz band. The bent performance of the designed fiber at 2.52 THz is also discussed. The results show that the fiber has low bending sensitivity, and can still maintain excellent birefringence and low confinement loss in the bending state. For the y polarization, the birefringence can be basically stabilized at the order of 10−4 within a bending radius of 10–60 cm.

Early detection of cancer cells using high-sensitivity dual-side polished photonic crystal fiber biosensors based on surface plasmon resonance

Early detection of cancer cells using high-sensitivity dual-side polished photonic crystal fiber biosensors based on surface plasmon resonance

Polished Fiber as a Promising Element for Coupling with a Microresonator with a Whispering Gallery Mode

Polished Fiber as a Promising Element for Coupling with a Microresonator with a Whispering Gallery Mode

A high sensitivity refractive index sensor based on microstructure fiber with simple structure and SPR effect

A novel dual-side polished photonic crystal fiber (PCF) based surface plasmon resonance (SPR) polarization filtering and refractive index (RI) sensor is presented in this paper. The cladding of PCF was composed of eight air holes and the outer surface was dual-sided polished and coated with gold film. Finite element method (FEM) was used for the simulation and design of the proposed sensor. Simulation results showed that sensor performance was better in analytes ranging from 1.33 to 1.42 RI. The wavelength and amplitude sensitivities at resonance wavelengths of 1269 and 995 nm were 27400 nm/RIU and −100.43 RIU−1 for an analyte of 1.42 and 1.41 RI, respectively, along with a spectral resolution of 3.64×10−6 RIU. Maximum loss of 52806 dB/m was obtained for an analyte of 1.41 RI towards Y-Polarization (Y-P). An extinction ratio of −105.374 dB was obtained using a fiber transferring length of 2 mm to achieve better polarization filtering effects. The proposed sensor is made of same size air holes which is easy to fabricate, cost effective, and shows better sensitivity and polarization filtering effects than several other sensors. It is expected that the sensor is suitable for wide RI detection range and capable of providing excellent polarization effect. The proposed sensor can be used for various applications including environmental detection, chemical sensing, biosensors, and pharmaceutical inspection.