Seven-core Fiber Research Articles

A microfiber biosensor for detection of AKT protein in human embryonic kidney cell lysate based on the vernier effect

The AKT protein is closely related to the cancer and diabetes. Rapid detection of AKT is very important in medical diagnosis. This paper proposed a parallel connected tapered seven-core fiber (PTSCF) biosensor to utilize vernier effect to improve sensitivity. Experimental results showed that 5.99 times improvements have been achieved in the refractive index sensing in the ranges of 1.333–1.337. By functionalizing AKT-Ab on the PTSCF sensor surface, a fast detection (<40 min) and an ultra-low limit of detection (LoD) of 0.044 ng/mL have been achieved for AKT protein solutions. The proposed PTSCF biosensor has been applied to detect AKT proteins in human embryonic kidney cell lysates and compared with those obtained by the western blotting (WB) method. Experimental results showed that the LoD of the PTSCF biosensor is 400-fold less than that of WB method. The proposed PTSCF biosensor holds great potential for applications in various medical fields, including intra-operative rapid detection, animal experiments, and pathological research.

A low crosstalk seven-core five-mode fiber for high density transmission and large capacity communication

We propose a seven-core five-mode fiber with air hole-assisted and high refractive index ring structure, and it can be fabricated by the stack-and-draw technique. The air hole auxiliary structure can significantly restrain the energy coupling between cores, and the high refractive index ring structure can meet the requirements of low intra-core crosstalk (XT) by improving the effective refractive index difference (Δn eff ) between adjacent modes. Through analyzing the influence of the number and arrangement of air holes on inter-core XT and effective mode field area (A eff ), it can be achieved the results that the inter-core XT is less than −44 dB/100 km and all the A eff values of LP modes are greater than 100 μm2 in the seven-core five-mode fiber when the wavelength is 1550 nm and the bending radius (R) is 80 mm. At the same time, the Δn eff between LP21 and LP02 mode can be controlled to 1.3 × 10−3 by adjusting the parameters of the high refractive index ring. In addition, the relative core multiplexing factor (RCMF) of the seven-core five-mode fiber is as high as 88.34. The simulation results show that the seven-core five-mode fiber has high spatial density and is suitable for the communication system with multi-channel and long-distance transmission.

Multi-Channel Seven-Core Fiber SPR Sensor Without Temperature and Channel Crosstalk

Multi-Channel Seven-Core Fiber SPR Sensor Without Temperature and Channel Crosstalk

Mid-infrared seven-core chalcogenide fiber with ultra-large mode field area and high beam quality

A seven-core chalcogenide fiber with an ultra-large mode field for mid-infrared range of 2.5–11 μm is designed and fabricated. Through manipulation of the core radius and pitch in the seven-core configuration, we are engaged in a comprehensive exploration of crosstalk characteristics and the mode field area (MFA). In addition, the relationship between the parameters of seven-core fiber for infrared and the beam quality of the output laser is analyzed for the first time. A theoretical MFA of 8914 μm2 can be calculated with a core radius of 24 μm and the pitch of 50 μm. This impressive MFA is realized through the deployment of an improved drilling technique in the fabrication of a Ge–As–Se seven-core fiber. The fiber has a relatively low loss at the wavelength range of 2.5–11 μm, and the minimum loss is 1.4 dB m−1 at 8.5 μm. The measured MFA of the fiber at 10.6 μm is 7364 μm2, which is 6.2 times higher than that of traditional stepped single-core fiber, but slightly lower than the theoretical value. The power delivery capability of the fiber has been significantly improved about two times compared with that of single-core fiber. The output beam quality factor M 2 is calculated as 1.13. In all, the seven-core fiber exhibits substantial potential for high-power laser propagation with high quality and flexibility.

Strain-insensitive micro torsion and temperature sensor based on a helical taper seven-core fiber structure.

We propose a multimode interference-based optical fiber NHTSN sensor with a helical taper for simultaneous measurement of micro torsion and temperature. The sensor consists of single mode fiber (SMF), no-core fiber (NCF), and seven-core fiber (SCF). A helical taper is fabricated in the SCF using a flame heater, forming the SMF-NCF-Helical Taper SCF-NCF-SMF (NHTSN) structure. Theoretical analysis and experimental results demonstrate that the introduction of helical taper not only imparts directionality to the torsion measurement, but also results in a significant improvement in torsion sensitivity due to the increased inter-mode optical path difference (OPD) and enhanced inter-mode coupling. In the experiment, the torsion sensitivity of the NHTSN sensor reaches -1.255 nm/(rad/m) in the twist rate (TR) range of -3.931 rad/m to 3.931 rad/m, which is a 9-fold improvement over the original structure. Further reduction of the helical taper diameter increases the sensitivity to -1.690 nm/(rad/m). In addition, the sensor has a temperature sensitivity of up to 97 pm/°C from 20 °C to 90 °C, and simultaneous measurement of torsion and temperature is attainable through a dual-parameter measurement matrix. The NHTSN sensor possesses advantages of compact size, high sensitivity, good linearity, and strain-independence, endowing it with potential applications in structural health monitoring (SHM) and engineering machinery.

Two curvature sensors based on no-core–seven-core fiber interference

Abstract Using the no-core fiber (NCF)–seven-core fiber (SCF) interference structure, two curvature sensors of Michelson interference type and Mach–Zehnder interference (MZI) type are proposed, respectively. The curvature sensor based on Michelson interference shows wavelength-modulation characteristics, the sensitivity is about −22.76 nm/m−1 with a linearity of 0.9823, the temperature sensitivity is only 0.054 nm/°C, and the effect of temperature on curvature can be negligible. The MZI sensor based on an enlarged taper-embedded cascaded structure is an intensity-modulated sensor. The sensitivities are −63.6271 dB m/m−1 and 93.3293 dBm/m−1 for the forward and reverse curvature, respectively, and the linearities are 0.9987 and 0.9930, respectively. But the strain sensitivity (8.357 × 10−4 dBm/με) of the MZI sensor is so tiny, which can avoid the strain cross effect. The two sensors can be used in the detection of the curvature at different (temperature/strain) conditions.

S-Tapered WaveFlex Biosensor Based on Multimode Fiber and Seven-Core Fiber Composite Structure for Detection of Alpha-Fetoprotein

S-Tapered WaveFlex Biosensor Based on Multimode Fiber and Seven-Core Fiber Composite Structure for Detection of Alpha-Fetoprotein

Wearable respiratory sensor based on Mach-Zehnder interferometer in seven-core fiber

In this paper, a wearable respiration sensor based on single-mode–gourd-shaped–seven-core–gourd-shaped–single-mode fiber structure is proposed and experimentally demonstrated for the first time. Attribute to the gourd-shaped structures between the seven-core fiber (SCF) and the single-mode fiber (SMF), the excitation of the supermode as well as the mode coupling in SCF are enhanced, and the sensor probe has good mechanical properties to ensure long-term respiration measurement. The static sensing experiment reveal that the sensor has a maximum sensitivity of −7.039 dB/m−1 in the curvature range of 0–4.66 m−1 with a low temperature cross-sensitivity of −0.03 m−1/°C. The sensor probe is embedded in a flexible textile band and the respiratory response of the sensor is experimentally achieved for different humans, different parts of the body (abdomen, chest, back), different states (motionless, exercising), and irregular respiration. In addition, repeatability and stability tests are carried out, and instability of the sensor is 0.003 Hz in 3 months. The sensor has advantages of high sensitivity, comfortable wearing, good stability, more importantly, the fixed position could be free on the upper body, indicating great potential in real-time respiration monitoring.

Axial strain and temperature sensor based on tapered seven-core fiber operating at dispersion turning point

An axial strain and temperature sensor based on a tapered seven-core fiber (SCF) operating at the dispersion turning point (DTP) is proposed. The tapered SCF sensor with DTP was fabricated by the one-step tapering method, and its axial strain characteristics and temperature characteristics were simulated and experimentally investigated. The experimental results show that the tapered SCF sensor operates near DTP with the highest axial strain sensitivity and temperature sensitivity, consistent with the simulation results. The maximum axial strain sensitivity of the tapered SCF sensor is 391.2 pm/με in the range of 0–300 με, and the maximum temperature sensitivity is 6.44 nm/°C in the range of 30-70°C. The sensor is highly sensitive to axial strain and temperature. It is promising for measuring physical quantities such as weak strain and temperature.

Speckle wavemeter based on a multi-core fiber and compressive imaging.

Random speckle patterns contain valuable information about the incident light. Researchers have successfully constructed spectrometers and wavemeters by utilizing the speckles generated by inter-mode interferences of a multimode fiber (MMF). However, cameras were often employed to record the speckle data in previous reports. The camera's high cost (especially in the near-infrared range), large size, and low response speed limit the applications in optical communications, metrology, and optical sensing. A seven-core fiber (SCF) was fused with an MMF to capture the speckle pattern, where each core coupled part of the speckle field. Furthermore, we take advantage of the space division multiplexing capability of the SCF by incorporating an optical switch. This allows the variety of speckles generated by the incidence of different cores into the MMF. A convolutional neural network (CNN) regression algorithm was designed to analyze the complicated speckle data. The experimental results show that the proposed wavemeter can resolve adjacent wavelengths of 1pm with an error of about 0.2pm. We also discussed how different lengths of MMF influence the wavelength resolution. In conclusion, our research presents a robust and cost-effective approach to a wavelength measurement device by use of a seven-core optical fiber.

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.

High security and low complexity SCMA-OFDM transmission system based on dual three-dimensional memory hyperchaotic in seven-core optical fibers

High security and low complexity SCMA-OFDM transmission system based on dual three-dimensional memory hyperchaotic in seven-core optical fibers

Temperature-compensated highly sensitive reflective SPR fiber sensor based on tapered Seven-core Fiber

Temperature-compensated highly sensitive reflective SPR fiber sensor based on tapered Seven-core Fiber

Bessel-beam-based side-view measurement of seven-core fibre internal core distribution

Bessel-beam-based side-view measurement of seven-core fibre internal core distribution

Cascadable 2D vector accelerometer based on differential sensitivity enhancement in internal seven-core fiber

Cascadable 2D vector accelerometer based on differential sensitivity enhancement in internal seven-core fiber

Signal-enhanced multi-core fiber-based WaveFlex biosensor for ultra-sensitive xanthine detection.

In this work, we introduce a novel multimode fiber (MMF) - seven core fiber (SCF) - MMF (MCM) optical fiber biosensor, also known as the WaveFlex biosensor (plasma wave assisted fiber biosensor), based on localized surface plasmon resonance (LSPR) for qualitative detection of xanthine. Xanthine is a purine base widely distributed in human blood and tissues, and commonly used as an indicator for various disease detections. The MCM sensor incorporates a tapered optical fiber structure, fabricated using the combiner manufacturing system (CMS), and is designed with SCF and MMF. By effectively harnessing LSPR, the sensor boosts the attachment points of biomolecules on the probe surface through immobilized tungsten disulfide (WS2)-thin layers, gold nanoparticles (AuNPs), and carbon nitride quantum dots (C3N-QDs). The functionalization of xanthine oxidase (XO) on the sensing probe further enhances the sensor's specificity. The proposed WaveFlex biosensor exhibits a remarkable sensitivity of 3.2 nm/mM and a low detection limit of 96.75 µM within the linear detection range of 100 - 900 µM. Moreover, the sensor probe demonstrates excellent reusability, reproducibility, stability, and selectivity. With its sensitivity, biocompatibility, and immense potential for detecting human serum and fish products, this WaveFlex biosensor presents a promising platform for future applications.

Lasing Spectrum Narrowing in a Seven-Core Fiber Laser with an Array of Bragg Gratings Inscribed by Femtosecond Pulses

Lasing Spectrum Narrowing in a Seven-Core Fiber Laser with an Array of Bragg Gratings Inscribed by Femtosecond Pulses

Theoretical Analysis of Space and Wavelength Division Multiplexing Er3+/Yb3+ Co-Doped Seven-Core Fiber Amplifier

Theoretical Analysis of Space and Wavelength Division Multiplexing Er3+/Yb3+ Co-Doped Seven-Core Fiber Amplifier

High-security three-dimensional optical transmission mechanism utilizing time-frequency-space interleaving disruption.

In this paper, we propose a high-security three-dimensional optical transmission system utilizing time-frequency-space interleaving chaos, which simultaneously enhances the reliability and security of the system. The four-wing 3D chaos model encrypts the time-frequency space interleaved modulation domain of a orthogonal time-frequency space (OTFS) modulation signal and the modulated phase information simultaneously, improving the system's security. We also experimentally validate the proposed high-security 3D-OTFS method, utilizing the hexadecimal modulation technique. The modulated OTFS signal achieves a transmission rate of 34.1 Gb/s over a 2-km seven-core fiber link, with the OTFS signal exhibiting a maximum of 1.31 dB receiver sensitivity gain compared to orthogonal frequency division multiplexing (OFDM) signals under the forward error correction threshold of the bit error rate. The achieved keyspace is equal to 5 × 1048. The findings demonstrate that the proposed high-security three-dimensional optical transmission mechanism, based on time-frequency-space interleaved disruption, exhibits excellent anti-interference ability and confidentiality performance. Consequently, it holds promising prospects for future applications in optical communications.

Incremental shape measurement with fiber Bragg gratings in a multi-core fiber for three-dimensional paths.

A multi-core fiber (MCF) provides a compact solution for three-dimensional (3D) shape measurement. In this Letter, an incremental shape measurement method for 3D paths is proposed, using an MCF based on fiber Bragg gratings (FBGs). A few FBG sets can iteratively provide plenty of strain information about the 3D path during navigation. The overall continuities of the curvature and torsion are improved based on intensive strain calculations. Meanwhile, the transformation matrix algorithm is used to reconstruct the shape of 3D paths. Dynamic measurement experiments of a seven-core fiber with two FBG sets are carried out to verify the incremental shape measurement method. This method shows a great performance of the different paths, with a maximum incremental position error of 4.68%.