Single Fiber Segments Research Articles

Experimental study on temperature-insensitive curvature sensor based on reflective all-fiber structure

In the paper, a reflective all-fiber sensor for curvature measurement has been proposed, which is composed of Mach-Zehnder interferometer (MZI) and Fabry-Pérot interferometer (FPI). The MZI section acts as curvature sensing unit and is made by splicing a section of twin-hole and dual-core fiber (THDCF) between two sections of seven-core fiber (SCF). The FPI section is made by introducing an FPI cavity between two segments of single mode fibers inside a hollow core capillary through using UV-curable resins and used to reflect the energy. The reflection spectrum information tuned by MZI has respond to bending change. The experiment results show the reflective sensor exhibits a high curvature sensitivity and low temperature sensitivity of −1.19 nm/m−1 and −1 pm/°C in the range of 0–5.7778 m−1 and 30–100 °C, respectively. With the advantages of reflective structure, compact size, easy fabrication, and low temperature crosstalk, our sensor could be widely used in practical applications.

Fiber Type Identification of Human Skeletal Muscle.

The technique described here can be used to identify specific myosin heavy chain (MHC) isoforms in segments of individual muscle fibers using dot blotting, hereafter referred to as Myosin heavy chain detection by Dot Blotting for IDentification of muscle fiber type (MyDoBID). This protocol describes the process of freeze-drying human skeletal muscle and isolating segments of single muscle fibers. Using MyDoBID, type I and II fibers are classified with MHCI- and IIa-specific antibodies, respectively. Classified fibers are then combined into fiber type-specific samples for each biopsy. The total protein in each sample is determined by Sodium Dodecyl-Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE) and UV-activated gel technology. The fiber type of samples is validated using western blotting. The importance of performing protein loading normalization to enhance target protein detection across multiple western blots is also described. The benefits of consolidating classified fibers into fiber type-specific samples compared to single-fiber western blots, include sample versatility, increased sample throughput, shorter time investment, and cost-saving measures, all while retaining valuable fiber type-specific information that is frequently overlooked using homogenized muscle samples. The purpose of the protocol is to achieve accurate and efficient identification of type I and type II fibers isolated from freeze-dried human skeletal muscle samples. These individual fibers are subsequently combined to create type I and type II fiber type-specific samples. Furthermore, the protocol is extended to include the identification of type IIx fibers, using Actin as a marker for fibers that were negative for MHCI and MHCIIa, which are confirmed as IIx fibers by western blotting. Each fiber type-specific sample is then used to quantify the expression of various target proteins using western blotting techniques.

Multipath Quasi-Distributed Acoustic Sensing Based on Space Division Multiplexing and Time-Gated OFDR

Quasi-distributed optic sensing system has been widely utilized in various applications for its simple configuration, high sensing resolution, and long sensing range. In large sensing network, multipath sensing arrays are needed to be monitored simultaneously. This paper proposes a multi-path quasi-distributed acoustic sensing system based on time-gated digital optical frequency domain reflectometry (TGD-OFDR) and spatial division multiplexing (SDM) technique. The single mode fiber segment between weak reflectors is efficiently used. In experiments, vibrations on two weak reflectors array are detected simultaneously, and crosstalk between pathes is analyzed. This multi-path system does not require additional hardware equipment and the bandwidth of the system is not sacrificed, which has great potential in large-scale sensing network.

A Compact Sensor Integrated in a Single Hollow Core Bragg Fiber for Simultaneous Measurement of Temperature and Strain

A compact sensor integrated in a single hollow core Bragg fiber is proposed and demonstrated for simultaneous measurement of strain and temperature. The sensor is manufactured by splicing a 3 mm long homemade Hollow Core Bragg Fiber (HCBF) sandwiched between two segments of Single Mode Fibers (SMFs) with a lateral offset at one end. Experimental results demonstrate that both Mach-Zehnder Interferometer (MZI) and Bragg resonant mechanism are coexisting in the HCBF-based sensor. Two sensing mechanisms have different strain and temperature sensitivities with good linearity. The axial strain sensitivities of -0.4 pm/με and 0.33 pm/με and the temperature sensitivities of 40.8 pm/ °C and 26.5 pm /°C are obtained by monitoring the wavelength shifts with axial strain and temperature in temperature range of 60-80°C. Therefore, simultaneous measurement of temperature and strain can be achieved by using a characteristic matrix approach. Due to the large refractive index difference between the core and cladding of the Bragg fiber, the length of HCBF for forming mode interference in the sensor could be greatly reduced. This makes the sensor more compact than most previous reports for simultaneous measurement of temperature and strain.

Yb-Doped Mode-Locked Fiber Laser Based on an All-Fiber Interferometer Filter

An interference filter is designed by fusing a segment of multi-core fiber (MCF) between two segments of multimode fibers (MMFs), which is then spliced between two segments of single mode fibers (SMFs). The light is split into the cladding and different cores of the MCF through the first segment of MMF, which is then coupled back into the core of SMF by the second segment of MMF. When the lengths of MCF are selected to be 4 mm and 10 mm, the 3 dB bandwidths of the filters around 1060 nm are 8.40 nm and 4.84 nm, respectively. Applying these filters in an Yb-doped fiber laser mode-locked by nonlinear polarization rotation, stable pulses have been obtained. Compared with the reported interference filters, the filter proposed in this paper has the advantages of simple fabrication process, compact structure and high environmental stability.

A Compact Fiber Cascaded Structure Incorporating Hollow Core Fiber With Large Inner Diameter for Simultaneous Measurement of Curvature and Temperature

A compact fiber cascaded structure for simultaneous measurement of curvature and temperature based on Fabry-Perot (FP) interference and anti-resonant (AR) mechanism is designed and experimentally demonstrated. The proposed structure is manufactured by sandwiching a segment of hollow core fiber (HCF) with large inner diameter and suitable length between two segments of single mode fibers (SMFs). Three sample sensors were fabricated with different HCF lengths. With theoretical analysis and experimental verifications, an HCF length of 1197 <i>&#x03BC;</i>m was selected for curvature and temperature experiments. The reflection fringes based on FP interference and transmission envelopes based on AR mechanism can be monitored to measure curvature and temperature variations at the same time. From experimental results, the sensitivities of curvature based on AR mechanism and FP interference are 0.2345 nm&#x002F;m^&#x2212;1 and -0.1021 nm&#x002F;m^&#x2212;1, and those of sensitivities of temperature are 0.0172 nm&#x002F;&#x00B0;C and 0.0017 nm&#x002F;&#x00B0;C, respectively. Therefore, the different responses in curvature and temperature based on two mechanisms enable the proposed structure to simultaneously measure curvature and temperature.

Notice of Removal: Practical Simulation Method on Multimode-No-Core-Multimode Fiber Structure Based on the Mode Expansion

In this paper, a simplified simulation method for multimode-no-core-multimode (MNM) fiber structures is developed and demonstrated. The method is based on the mode expansion in the vectorial form, taking account of a complete set of guided modes. The simulated results are in good agreement with the experimental results. Also, it is shown that mode distribution of an input multimode fiber (MMF) is an influence on multimode interference(MMI) in the MNM fiber structure and can be controlled by using a single mode fiber(SMF) segment coupled to it. The proposed method provides an effective way for the designs of multimode-interference(MMI)-based fiber devices, which particularly contain a lot of modes.

Intensity-modulated bend sensor by using a twin core fiber: theoretical and experimental studies.

A new optical fiber bend sensor is proposed and demonstrated based on a sandwich structure created by splicing a segment of twin core fiber (TCF) between two segments of single mode fibers (SMFs). One core of the TCF is aligned with the cores of two segments of SMFs. An incident beam is directed into the TCF by the lead-in SMF. Light couples back and forth between two cores. The bend sensing performance of the sensor is investigated by intensity-modulated method. The intensity of the operation wavelength is modulated by the change of refractive index and geometrical deformation in the bent TCF. Experimental results show such a bend sensor achieves sensitivity of +0.671 /m-1 and resolution of 0.003 m-1 in the range of 0 to 1.25 m-1. In addition, the sensitivity and bend measurement range can be flexibly adjusted through selection of the length of TCF and sensing configuration. As such, the proposed sensor can be further developed for large or small bend ranges measurement.

Experimental and numerical investigation on hollow core photonic crystal fiber based bending sensor.

Recent progress in designing optimized microstructured optical fiber spreads an application scenario of optical fiber sensing. Here, we investigate the bending measurement based on a specially designed hollow core photonic crystal fiber (HC-PCF). Numerical simulation indicates that the bending sensitivity is mainly determined by the diameter of the hollow core and also depends on the coupled modes. Experimentally, a direction-independent bending sensor is fabricated by sandwiching a segment of specially designed HC-PCF into two segments of single mode fibers. The bending sensitivity of our device is improved 10 times by increasing the diameter of the hollow core. Bending measurement is validated at two orthogonal planes. The maximum sensitivity up to 2.8nm/deg is obtained at 14° bending angle. Additionally, a low thermal sensitivity of 2.5pm/°C is observed from 18°C to 1000°C. The sensor is robust, easy to fabricate and cost effective, which is promising in the field of small-angle bending measurement under a large temperature range.

Thin-core fiber-optic biosensor for DNA hybridization detection

A real-time label-free DNA biosensor based on thin-core fiber (TCF) interferometer is demonstrated experimentally. The proposed biosensor is constructed by splicing a TCF between two segments of single mode fibers (SMFs) and integrated into a microfluidic channel. By modifying the TCF surface with monolayer poly-l-lysine (PLL) and single-stranded deoxyribonucleic acid (ssDNA) probes, the target DNA molecules can be captured in the microfluidic channel. The transmission spectra of the biosensor are measured and theoretically analyzed under different biosensing reaction processes. The results show that the wavelength has a blue-shift with the process of the DNA hybridization. Due to the advantages of low cost, simple operation as well as good detection effect on DNA molecules hybridization, the proposed biosensor has great application prospects in the fields of gene sequencing, medical diagnosis, cancer detection and environmental engineering.

Switchable multi-wavelength erbium-doped fiber ring laser based on a tapered in-line Mach–Zehnder interferometer

In this paper, a switchable multi-wavelength erbium-doped fiber ring laser based on a tapered in-line Mach–Zehnder interferometer is proposed. The in-line Mach–Zehnder interferometer is fabricated by splicing a large-core fiber between two segments of single mode fibers, in which the first splicing point is tapered and the second splicing point is connected directly. By carefully rotating the polarization controller, switchable single-, dual-, triple- and quad-wavelength lasing outputs can be obtained with a side mode suppression ratio higher than 50 dB. The maximal peak power difference of multi-wavelength lasing is 3.67 dB, demonstrating a good power equalization performance. Furthermore, the proposed laser is proven to be very stable at room temperature. The wavelength shifts and peak power fluctuations are less than 0.02 nm and 1.3 dB over half an hour. In addition, stable quintuple-wavelength lasing with a side mode suppression ratio higher than 50 dB can also be realized when the filter length is changed.

Contractile Properties of Single Muscle Fiber and Their Relations to Whole Muscle Strength in Korean Young Male

PURPOSE This study investigated the muscle fiber type-related contractile properties and examined the relationship between whole limb muscle strengths and single muscle fiber contractile properties in Korean men. METHODS Six Korean men (29.8±1.49 yr) were recruited and participated in the study. Samples were obtained from vastus lateralis muscles. CSA, Po, SF, Vo of single fiber segments were measured using an isometric force transducer and a high-speed motor. Silver staining was performed to identify MHC isoform composition of single muscle fiber segments. Multiple regression was tested to identify the relationship between single muscle fiber contractile properties and whole muscle strength. RESULTS MHC isoforms were distributed in different proportion (Type I: 57.3%, IIa: 34.2%, IIa/IIx: 4.3%, IIx: 4.3%). CSA of type IIx were smaller compared to type I (-50%) and type IIa (-57.5%). Po in type IIa was 12.9% higher compared to type I (p<.05). While SF in type IIa were 7.7% higher than type I, type IIx were higher than type I, IIa, IIa/IIx (31.4%, 25.7%, 30.9%). Vo increased in the order type I<IIa<IIa/IIx<IIx. There was positive correlation between single fiber and properties (Po vs. thigh strength: r2=.248, Po vs. thigh power: r2=.058, Vo vs. thigh power: r2=.095). CONCLUSIONS These results suggest that single muscle fiber contractile properties were exclusively dependent on fiber type isoforms, ruling out a possibility of race-induced difference in fiber type-matched contractile properties. 색인어: 한국남성, ë‹¨ì¼ê·¼ì„¬ìœ , ê·¼ë ¥, ê·¼ì„¬ìœ ìœ í˜•, í•˜ì´ë¸Œë¦¬ë“œì„¬ìœ Keywords: Korean men, Single muscle fiber, Whole muscle strength, MHC isoform, Hybrid fiber

The prediction of elastic modulus of the mullite fiber network based on the actual structure architecture

Accurately establishing the relationship between the network architecture characteristics and performance of fibrous porous ceramics is instructive for structural design and performance control. In the present work, fibrous, high porous (82.87–90.02%), low density (0.247–0.512g/cm3) and low elastic modulus (50.62–188.56MPa) mullite ceramics were fabricated by freeze casting. The three dimensional network architectures were characterized by X-ray tomography technique and quantitatively analyzed by 3D image analysis software (imorph, www.imorph.fr). The radius (5.04µm), types, lengths (64.72–96.49µm) and orientations (0.87–1.45, anisotropy parameter) of fiber segments in the network architecture were investigated. The extracted results were employed to predict the Young's modulus of the mullite fibrous porous ceramics according to a model based on the bending and axial compression of single fiber segment. The predicted Young's modulus agreed well with the experimental results. The differences of Young's modulus and Poisson ratio between the prediction and the model of Markaki and Clyne were compared. The comparison showed that the difference became larger when the aspect ratio of the fiber segment was less than 6 due to the effect of axial compression. The predicted Poisson ratio had a certain dependence on fiber segment aspect ratio and got close to the constant (1/π) reported by Markaki and Clyne with the increase of fiber segment aspect ratio.

In-fiber Mach–Zehnder interferometer based on a Nd-doped double-clad fiber for switchable single and dual-wavelength EDF laser application

We present an experimental study of a novel Mach–Zehnder in-fiber interferometer and its application for single and dual-wavelength operation of a ring cavity fiber laser. The proposed in-fiber interferometer, consisting of a segment of Nd-doped fiber spliced between two segments of standard single mode fibers, exhibits a wavelength periodical transmission spectrum with a period of 2.8 nm and a fringe contrast of ~0.8 dB. The Mach–Zehnder interferometer (MZI) is used as a spectral filter to obtain switchable single and dual-wavelength operation of an Er-doped fiber laser (EDFL). Laser emission with laser lines spectral width less than 0.22 nm and wavelength separation of 2.8 nm corresponding to transmission spectrum wavelength period of the MZI is obtained. The stability of the dual-wavelength operation of the EDFL is also discussed. The use of the proposed in-fiber MZI as a reliable, spectral filter to achieve stable single and dual-wavelength laser generation in a ring cavity fiber laser is experimentally demonstrated.

MMI filters configuration for dual-wavelength generation in a ring cavity erbium-doped fibre laser

Dual wavelength laser generation has been of constant interest due to their applications in optical communications and teraheartz generation. A novel configuration for Dual-wavelength laser generation based on the use of a couple of multimode interference (MMI) filters is demonstrated in a ring cavity Erbium-doped fibre laser. The MMI filters consist of a segment of no-core fibre spliced between two SMF-28 single mode fibre segments. The MMI filters configured as a Mach-Zehnder interferometer, are used as transmission spectral filters for simultaneous generation of two laser wavelengths. An optical attenuator is used to adjust the intra-cavity losses for dual-wavelength laser generation. Laser emission at 1540.4 and 1554 nm for a wavelength separation of ~13.6 nm is obtained. The laser wavelengths output power stability variations with the applied pump power is also experimentally discussed. The use of MMI filters in the proposed dual-wavelength laser filter is experimentally demonstrated as a reliable device for dual-wavelength generation in fibre lasers.

Threshold and maximum power evolution of stimulated Brillouin scattering and Rayleigh backscattering in a single mode fiber segment

The behavior of stimulated Brillouin scattering (SBS) and Rayleigh backscattering phenomena, which limit the forward transmission power in modern, ultra-long haul optical communication systems such as dense wavelength division multiplexing systems is analyzed via simulation and experimental investigation of threshold and maximum power. Evolution of SBS, Rayleigh scattering and forward powers are experimentally investigated with a 25 km segment of single mode fiber. Also, a simple algorithm to predict the generation of SBS is proposed where two criteria of power thresholds was used for comparison with experimental data.

Efflux Time Courses of Cytosolic Proteins from Rabbit Skinned Muscle Fibers Reflect Dissociation of Enzyme Complexes

In many multi-system metabolic diseases characterized by mitochondrial dysfunction (e.g. Myalgic Encephalomyelitis), glycolysis appears to be an important compensatory pathway for generating ATP. It is postulated that glycolytic enzymes form a complex that enhances the rate of ATP production through substrate channeling of metabolic product intermediates. To search for evidence of a reduced diffusion coefficient indicative of supramolecular complexes, we examined the efflux of endogenous glycolytic enzymes from rabbit psoas muscle fibers. Single fiber segments were skinned in oil and transferred to physiological salt solution. Cytosolic proteins that diffused into the solution were separated by gel electrophoresis and compared to load-matched standards for quantitative analysis. A radial diffusion model incorporating the dissociation and dissipation of supramolecular complexes accounts for an initial lag and subsequent efflux of glycolytic enzymes. The model includes terms representing protein crowding, myofilament lattice hindrance, and cytomatrix binding. Optimization of model to data returned estimates of apparent diffusion coefficients that were very low at the onset of diffusion (∼10−10 cm2 s−1) but increased with time as cytosolic protein density decreased. The initial values are consistent with the presence of complexes in situ; higher later values (e.g., 0.2 × 10−7 cm2 s−1 for phosphofructose kinase), with molecular sieving and transient binding of dissociated proteins. Channeling of metabolic intermediates via enzyme complexes may enhance production of ATP at rates beyond that possible with randomly distributed enzymes, thereby matching supply with demand. Metabolic channeling may allow glycolysis to better compensate for reduced ATP production in aerobic metabolic diseases.

Important considerations for protein analyses using antibody based techniques: down‐sizing Western blotting up‐sizes outcomes

Western blotting has been used for protein analyses in a wide range of tissue samples for >30 years. Fundamental to Western blotting success are a number of important considerations, which unfortunately are often overlooked or not appreciated. Firstly, lowly expressed proteins may often be better detected by dramatically reducing the amount of sample loaded. Single cell (fibre) Western blotting demonstrates the ability to detect proteins in small sample sizes, 5-10 μg total mass (1-3 μg total protein). That is an order of magnitude less than often used. Using heterogeneous skeletal muscle as the tissue of representation, the need to undertake Western blotting in sample sizes equivalent to single fibre segments is demonstrated. Secondly, incorrect results can be obtained if samples are fractionated and a proportion of the protein of interest inadvertently discarded during sample preparation. Thirdly, quantitative analyses demand that a calibration curve be used. This is regardless of using a loading control, which must be proven to not change with the intervention and also be appropriately calibrated. Fourthly, antibody specificity must be proven using whole tissue analyses, and for immunofluorescence analyses it is vital that only a single protein is detected. If appropriately undertaken, Western blotting is reliable, quantitative, both in relative and absolute terms, and extremely valuable.

A simple fracture energy prediction method for fiber network based on its morphological features extracted by X-ray tomography

The fracture behavior of a novel porous metal fiber sintered sheet (PMFSS) was predicted using a semi-empirical method combining the knowledge of its morphological characteristics and micro-mechanical responses. The morphological characteristics were systematically summarized based on the analysis of the topologically identical skeleton representation extracted from the X-ray tomography images. The analytical model firstly proposed by Tan et al. [1] was further modified according to the experimental observations from both tensile tests of single fibers and sintered fiber sheets, which built the coupling of single fiber segment and fiber network in terms of fracture energy using a simple prediction method. The efficacy of the prediction model was verified by comparing the predicted results to the experimental measurements. The prediction error that arose at high porosity was analyzed through fiber orientation distribution. Moreover, the tensile fracture process evolving from single fiber segments at micro-scale to the global mechanical performance was investigated.

Self-starting and overclocking a harmonically mode-locking WRC-FPLD with a dual-loop feedback controller for 10 Gb s−1 pulse-data transmission

The self-starting and overclocking of a harmonically mode-locked weak-resonant-cavity Fabry–Perot laser diode (WRC-FPLD) with a dual-loop coupled optoelectronic oscillator (COEO) based feedback controller is demonstrated to perform a clock-free pulsed data transmission at 10 Gb s−1. The WRC-FPLD is considered as the preferred candidate for harmonic mode-locking due to its highly asymmetric cavity architecture, whereby the spontaneous noise can be significantly suppressed without inducing large intra-cavity loss. With the dual-loop COEO configuration, the WRC-FPLD can be boosted to four times of its original modulation bandwidth such that the pulsed carrier quality can be refined. The structure-optimizing principle with the closed-loop model is corroborated by the effective spurious-noise-suppression. The lowest phase noises as low as −100 dBc Hz−1 at 10 kHz with corresponding RMS timing jitter of 0.67 ps are measured. This is achieved by individually inserting 100 and 120 m long single mode fiber segments into two decoupled arms, the dual-loop COEO before the optical receiver pair. The BER performance reaches a minimum with the optimized SMF segment lengths. However, the spurious peaks arise to degrade the BER performance as the phase noise and jitter are inevitably enlarged when inserting longer SMF segments. After modulating the optimized output pulse train with the pseudo-random-bit-sequence data triggered by the same COEO clock, the SNR can achieve 10.9 dB and the receiving sensitivity is −19.2 dBm.