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A Method to Process Hollow-Core Anti-Resonant Fibers into Fiber Filters
摘要： Hollow-Core Anti-Resonant Fiber (HC-ARF) shows promising applications. Nevertheless, there has been a persistent problem when it comes to all-fiber integration due to a lack of HC-ARF-based fiber components. In response to this remaining challenge, we investigate a reliable, versatile and efficient method to convert an HC-ARF into a fiber filter. By locally heating an HC-ARF with a CO2 laser, the fiber structure becomes deformed, and cladding capillaries shrink to produce a thicker wall. This process is analogous to “writing” a new fiber with a thicker wall on the original fiber, resulting in creating new high loss regions in the original transmission bands. Thus, the construction of a fiber filter is realized by “writing” a new fiber on the original fiber. The feasibility of this method is confirmed through experiments, adopting both one- and two-layer HC-ARF. The HC-ARF-based fiber filters are found to have transmission spectra consistent with simulation prediction. Both band pass and band reject fiber filters with more than a 20-dB extinction ratio are obtainable without extra loss. Thus, an in-fiber HC-ARF filter is demonstrated by the CO2 writing process. Its versatile approach promises controlled band selection and would find interesting applications to be discussed.
关键词： fiber filters,anti-resonant,hollow core fibers,fabrication,photonic crystal fibers
更新于2025-09-23 15:22:29
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Tapered Fibers Combined With a Multi-Electrode Array for Optogenetics in Mouse Medial Prefrontal Cortex
摘要： Optogenetics offers many advantages in terms of cell-type specificity, allowing to investigate functional connectivity between different brain areas at high spatial and neural population selectivity. In order to obtain simultaneous optical control and electrical readout of neural activity, devices called “optrodes” are employed. They are typically composed of a linear array of microelectrodes integrated on a slender probe shafts combined with flat-cleaved optical fibers (FF) placed above the recording sites. However, due to tissue absorption and scattering, light delivered by the FF unevenly illuminates the region of interest. This issue is of particular relevance when cellular populations are disposed along the dorso-ventral axis, such as in medial prefrontal cortex (mPFC) where cortical layers are aligned vertically. The study presented here aims at using tapered optical fibers (TFs) in combination with a 16-electrode neural probe to better access neural populations distributed along the dorso-ventral axis in the mPFC of newborn mice, restricting light delivery over a specific portion of the cortical layer of interest. Half of the TF surface is coated with a reflecting metal blocking the light to enable light delivery from one side of the probe’s shaft only, with the probe base being designed to host the fiber without interfering with the wire-bonds that connect the recording sites to a printed circuit board. Monte-Carlo simulations have been implemented to define the relative TF-probe position and to identify the light intensity distribution above the recording sites. In vivo recordings indicate that simultaneous optical stimulation and electrical readout of neural activity in the mPFC benefit from the use of the engineered TF-based optrode in terms of a more uniform light distribution along the dorso-ventral axis and the possibility of restricting light delivery to a subset of electrical recording sites of interest.
关键词： optogenetics,medial prefrontal cortex,tapered fibers,optrode,optical fibers
更新于2025-09-23 15:22:29
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Experimental and numerical investigation to rationalize both near-infrared and mid-infrared spontaneous emission in?Pr3+ doped selenide-chalcogenide fiber
摘要： This contribution reports on detailed experimental and numerical investigations of both near-infrared (NIR) and mid-infrared (MIR) photoluminescence obtained in praseodymium trivalent ion doped chalcogenide-selenide glass fiber. The experimental analysis allows for the identification of the radiative transitions within the praseodymium ion energy level structure to account for the photoluminescent behavior. Numerical analysis is carried out using the rate equations' approach to calculate the level populations. The numerical analysis provides further insight into the nature of the radiative transitions in the Pr3+ ion doped chalcogenide-selenide glass and allows for the identification of the electronic transitions, which contribute to the observed photoluminescence. The numerical results agree well with the experimental results.
关键词： chalcogenide glass fibers,optical fiber modelling,lanthanide doped fibers
更新于2025-09-23 15:22:29
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Single-mode large-mode-area Er–Yb fibers with core based on phosphorosilicate glass highly doped with fluorine
摘要： Single-mode Er–Yb fibers with the core based on a phosphorosilicate glass matrix (up to 6.5 mol.% P2O5) highly doped with fluorine (up to 0.9 wt.%) were fabricated using an all-gas-phase modified chemical vapor deposition method. The core numerical aperture was in the range of 0.07–0.08 relative to the pure silica, which allowed us to increase the single-mode core diameter up to 20 μm. The slope efficiency in lasers based on the fabricated fibers reached 34% relative to the launched pump power.
关键词： fiber lasers,optical fibers,erbium–ytterbium fibers,erbium-doped fiber amplifiers
更新于2025-09-23 15:22:29
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[IEEE 2018 International Flexible Electronics Technology Conference (IFETC) - Ottawa, ON, Canada (2018.8.7-2018.8.9)] 2018 International Flexible Electronics Technology Conference (IFETC) - Smart Fibers Based on Low Dimensional Conductive Materials
摘要： The fragility of traditional metallic or semi-conductive materials hinders their application in flexible electronics. Low dimensional materials including carbon nanotubes, graphene and metal nanowires own outstanding flexibility and have been wildly used to fabricate flexible devices. Bendable/stretchable substrate is another key component of flexible electronics. Various thin polymer films made of polyethylene terephthalate, polyimide, polydimethylsiloxane et. al. were adopted. However, the air impermeability of these substrates will cause discomfort of humanbeing if applied in wearable electronics. Fiber is an ideal substrate for flexible and wearable electronics due to its excellent flexibility/stretchability, superior breathability, abundant microstructure and low cost. Herein, a series of conductive elastomers and strain sensors were fabricated by combining the low dimensional conductive materials with fiber substrates and regulating the microstructure on the interface. With the help of 'twining spring' hierarchical architecture, silver nanowire-double covered yarn (Ag NW-DCY) composite fibers with ultrahigh stretchability were obtained. The conductivity of the composite fibers reached up to 104 S/cm and remained 90% at 2000% tensile strain. Commercial electronic components (LED arrays) were integrated onto a transparent, foldable and stretchable substrate using the composite fibers as stretchable electric wiring, demonstrating the potential application in large-area stretchable electronics. When AgNWs were replaced with graphene, strain sensing fiber with high sensitivity and large working range (100% strain) were fabricated, which enabled the detection of multiple deformation forms, including tensile strain, bending, and torsion. We employ the fibers as wearable sensors, realizing the monitoring of full-range human activities and intricate movement combinations of a robot. Besides, these fibers exhibits fast response, low hysteresis and excellent cycling stability. Another advantage needs to be noted is that these fiber are fabricated by a facial dip coating method, which can be scaled up easily. These smart fibers are of great meaning to the development of flexible and wearable electronics.
关键词： smart textiles,stretchable conductive fibers,wearable electronics
更新于2025-09-23 15:22:29
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High-Temperature Filter Based on Silicon Carbide for Aggressive Fluids and Gases
摘要： In this paper, we developed a production method for items based on mesh silicon carbide that are suitable for cleaning aggressive fluids, melts, and gases from foreign inclusions at high operating temperatures. The resulting products can also be used for filtering fuel mixtures.
关键词： carbon fibers,silicization,silicon carbide,microstructure,composite filter
更新于2025-09-23 15:22:29
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Control of orbital angular momentum of light in optofluidic infiltrated circular photonic crystal fibers
摘要： Orbital angular momentum (OAM) of light has been of great interest to enhance the data transmission capacity in optical communication systems. In this regards, new designs of optical fibers have been developed to transmit OAM modes. Circular photonic crystal fibers (C-PCFs) with an air-core in the center are good candidates for guiding OAM of light. By changing the geometrical parameters of the C-PCFs, one can control the topological charge (l) associated with OAM order. However, practically it is of significant interest to keep the geometrical parameters fixed and control the OAM characteristics by introducing optical fluid into the C-PCF. Therefore, in this paper, we propose for the first time controlling OAM characteristics such as l, dispersion and confinement loss based on optofluidic infiltrated C-PCFs. To this end, optofluidics with various refractive indices are introduced into the first ring of air holes in the cladding and mode characteristics are compared with those of uninfiltrated C-PCF. The results show that the OAM modes can be well controlled in optofluidic-infiltrated C-PCFs over the wavelength range of 1.25-2.0 μm with good dispersion and loss characteristics. Also, the dispersion curve can be flattened when an optical fluid with a proper refractive index is infiltrated into the C-PCF.
关键词： circular photonic crystal fibers,orbital angular momentum,optical fluid,mode control.
更新于2025-09-23 15:22:29
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Patterns of Subsequent Progression of Localized Retinal Nerve Fiber Layer Defects on Red-free Fundus Photographs in Normal-tension Glaucoma
摘要： Purpose: To investigate patterns of subsequent progression of localized retinal nerve fiber layer (RNFL) defects and to quantify the extent of progression in normal-tension glaucoma (NTG) patients. Methods: Thirty-three eyes of 33 consecutive NTG patients who had shown continuous progression of localized RNFL defect on serial red-free fundus photographs were selected for the study. Patterns of subsequent progression of localized RNFL defects were categorized, and extents of progression were quantified. Serial evaluations of disc stereophotographs and visual fields were also performed to detect progression. Results: The most common pattern was continuous widening of the defect towards the macula (n = 11, 33.3%) followed by sharpening of the defect border after widening of the defect towards the macula (n = 5, 15.2%), continuous widening of the defect away from the macula (n = 2, 6.1%), and deepening of the defect after appearance of a new defect (n = 2, 6.1%). Four eyes (12.1%) simultaneously showed two patterns of subsequent progression. In 13 eyes that showed continuous widening of the defect, subsequent angular widening towards the macula and away from the macula were 9.2 ± 6.0° (range, 1.1° to 24.4°; n = 11) and 5.2 ± 4.9° (range, 0.3° to 11.3°; n = 2), respectively. Thirty-two eyes showed no progression of optic disc cupping. Out of the 21 eyes in which Humphrey central 30-2 threshold visual field tests were performed after progression of RNFL defects, 15 eyes showed no deterioration in the visual field. Conclusions: There were nine patterns of subsequent progression of localized RNFL defects. Among them, continuous RNFL loss proceeding temporally was the most common one. Initial progression of the defect proceeded temporally, especially in the defect located at the inferior fundus, might be at a risk of further RNFL loss temporally.
关键词： Nerve fibers,Low tension glaucoma,Progression
更新于2025-09-23 15:22:29
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Application of the Hollow Core Fiber Ended with Fiber Microlens in the Multiphoton Excitation Setup
摘要： In this paper an ultrathin lensed fiber-optics probe for multiphoton fluorescence endoscopy is presented. The probe is made by attaching a segment of multimode (MM) fiber to the distal end of the hollow core, photonic bandgap fiber (HCPBF) and generating a curved surface at the tip of the MM fiber using a fiber arc fusion splicer the electric arc of a fusion splicer. The curved surface served as a micro fiber-optic lens and focused the exiting light beam. It simultaneously protected the HCF tip against contamination.
关键词： fiber microlens,ultrafast optics,photonic crystal fibers
更新于2025-09-23 15:22:29
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Fluorescence Study of the Hydrolytic Degradation Process of the Polysiloxane Coatings of Basalt Fibers
摘要： Basalt fiber surfaces were modified using different silane aqueous solutions to generate a variety of polyorganosiloxane coatings. After removing the commercial coating of the fibers by calcination and subsequent activation processes, polysiloxanes were grafted on the fiber surfaces. Three aqueous solutions were used for the silanization: i) γ-aminopropyltriethoxysilane, APTES; ii) γ-aminopropylmethyldiethoxysilane, APDES, and iii) a mixture of 50% by weight of both APTES+APDES. The silanized fibers were chemically labeled with fluorescein isothiocyanate to be immersed afterwards in different aqueous solutions (pH=7) to study the hydrolytic degradation of the polysiloxane coatings. The hydrolysis phenomena were monitored by steady state fluorescence at different temperatures to subsequently study the kinetics of the process. The hydrolysis process was also studied by monitoring the pH of the solution in which the silanized fibers were immersed as a function of time. The data obtained from fluorimetry were fitted to an integrated expression arising from a first order kinetic process, which allowed estimation of the activation energies of the hydrolytic degradations. The results indicated that although the hydrolytic rate of the polysiloxane coatings increased in the order APDES<APDES+APTES<APTES, differences in the mechanism were not the cause of that order; the initial concentration of siloxane bonds able to be hydrolyzed was responsible.
关键词： polyorganosiloxane,hydrolytic degradation,fluorescence,Basalt fibers
更新于2025-09-23 15:22:29