Four-core Fiber Research Articles

A four core fiber temperature and strain dual parameter sensor based on T-shaped taper

A four core fiber temperature and strain dual parameter sensor based on T-shaped taper is proposed and prepared. The sensor is composed of single-mode fiber (SMF), multi-mode fiber (MMF), and four core fiber (FCF). Among them, MMF plays a role in beam expansion, and FCF is tapered and fused with SMF to form a T-shaped taper structure, thereby preparing a sensor based on Mach Zehnder interference principle. When the external environmental temperature and strain change, due to thermal effect and elastic optical effect, the refractive index of the FCF cladding and fiber core changes differently, resulting in shift in the interference spectrum. Based on the temperature and strain sensitivity at different interference valleys, the temperature and strain dual parameter matrix equation of the sensor can be obtained. The experimental results indicate that when the temperature rises within the range of 30 ℃ to 90 ℃, the sensor spectrum shows a red shift phenomenon, and the maximum temperature sensitivity can reach 55 pm/ ℃. When the strain increases within the range of 0 με∼ 2000 με, the transmission spectrum of the sensor exhibits a blue shift phenomenon, and the maximum strain sensitivity can reach −2.6 pm/ με. Finally, based on the experimental results, the matrix equation for dual parameter sensing can be obtained. This sensor is easy to manufacture and has high sensitivity. It can measure sensing parameters normally in micro magnetic and micro electric field environments.

Dual Mach-Zehnder Interferometer Based on DCF and FCF for Temperature and Strain Measurement

In this paper, a dual Mach-Zehnder interferometer for measuring both temperature and strain is proposed and verified by experiments. The sensor configuration involves cascading a four-core fiber and a double-clad fiber between two single-mode fibers. By exploiting the different responses of the two Mach-Zehnder interferometers to temperature and strain, we construct a matrix using two selected resonance dips from the transmission spectra, so that both temperature and strain can be measured simultaneously. The experimental results show the sensor’s remarkable performance, with the maximum temperature sensitivity of −94.2 pm/°C and the maximum strain sensitivity of 2.68 pm/µε. The maximum temperature error and strain error are found to be ±0.35 °C and ±4.8 µε, respectively. Compared with other optical fiber sensors, the sensor has high sensitivity, a simple structure, and ease to manufacture and implement, making it a structure choice for applications in quality inspection of materials.

Four-core fiber-based multi-tapered WaveFlex biosensor for rapid detection of Vibrio parahaemolyticus using nanoparticles-enhanced probes.

Infections caused by Vibrio parahaemolyticus (V. parahaemolyticus) can be highly fatal, making rapid and sensitive detection of them is essential. A new optical fiber biosensor based on localized surface plasmon resonance (LSPR) phenomenon is developed in this paper. A tapered-in-tapered fiber structure based on MFM is constructed by using four-core fiber (FCF) and multi-mode fiber (MMF) to qualitatively detect different concentrations of V. parahaemolyticus. The sensor successfully excites the LSPR phenomenon and increases the attachment point of biomolecules on the probe surface by fixing gold nanoparticles (AuNPs), molybdenum disulfide nanoparticles (MoS2-NPs) and cerium dioxide nanorods (CeO2-NRs). The functionalization of polyclonal antibodies on the probe surface can improve the specificity of the sensor. The linear detection range of the developed sensor was 1 × 100-1 × 107 CFU/mL, the sensitivity was 1.61 nm/[CFU/mL], and the detection limit was 0.14 CFU/mL. In addition, the reusability, reproducibility, stability, and selectivity of the sensor probe are also tested, which shows that the sensor has great application prospects.

Vectorial Distributed Vibration Sensing Based on Two-Beam $\phi$-OTDR and Four-Core Fiber

Vectorial Distributed Vibration Sensing Based on Two-Beam $\phi$-OTDR and Four-Core Fiber

Fiber-optic Michelson interferometric trace dimethyl methyl phosphate sensor based on MnO2/ZnO composites film

A dimethyl-methyl phosphonate (DMMP) sensor based on MnO2/ZnO composite film integrated fiber-optic Michelson interference structure is proposed. The sensing structure is formed by a thick taper between a single-mode fiber (SMF) and a four-core fiber (FCF), and then the no-core fiber (NCF) is spliced at the other end of the FCF. To enhance reflection, the silver film was deposited on the end of the NCF, and the fiber optic Michelson interference structure is formed. MnO2/ZnO composite sensing film was deposited on the FCF surface, and the structure, morphology, and properties of the sensing material were analyzed by x-ray diffraction, Scanning electron microscopy, Fourier-transform infrared spectroscopy, x-ray photoelectron spectroscopy, etc. The sensitivity and the response time of the sensor are 0.3478 dB/ppm and 180 s, respectively. The sensor has good selectivity and stability, and it has a good application prospect in trace DMMP detection with high sensitivity.

Temperature-insensitive vector curvature sensor based on four-core fiber offset structure

Vector curvature measurement is very important in industrial fields with the unavoidable problem of temperature crosstalk. To improve the detection performance, a novel temperature-insensitive vector bending sensor have been proposed in the paper. The sensor is fabricated by core-offset splicing a segment of four-core fiber (FCF) between two single-mode fibers (SMFs). The Mach-Zehnder interference and the recognition ability of bending directions are enhanced by the core-offset structure. The experimental results demonstrate the curvature sensitivities of our sensor reach 38.16 nm/m−1, 37.46 nm/m−1, 4.99 nm/m−1 and −7.12 nm/m−1 in different bending directions within the range of 0.346–0.49 m−1. The average temperature sensitivity is only −6.67 pm/℃ in the range of 30–90 °C. The all-fiber, low cost, high sensitivity, and excellent vectoriality make our sensor more potential in harsh, complex industrial environment.

Sensitivity-enhanced two-dimensional bending sensor based on single-mode fiber measurement

A sensitivity-enhanced two-dimensional bending sensor using four-core fiber (FCF) transition to realized single-channel demodulation of seven-core fiber Bragg grating (FBG) is proposed. A section of FCF was added between the single-mode fiber (SMF) and the seven-core fiber (SCF), and the thermal diffusion technology (TDT) was used so that the signal of the SMF could be transmitted to the three side cores of the SCF through the FCF. Then, a 45° reflective circular cone (45° RCC) is fabricated at the end of the SCF, enabling the coupling of the symmetrical side core signals of the SCF. By inscribing the FBGs with different reflection wavelengths on the side cores of the SCF, the signals of each side core can be distinguished during single-channel demodulation. Monitoring the reflection wavelength shifts of the FBGs on the SCF can realize two-dimensional bending measurements. Furthermore, through the differential operation of the symmetrical side cores, the bending sensitivity can be enhanced while eliminating temperature crosstalk. The proposed sensor with high integration, high sensitivity, and reduced crosstalk, is expected to be applied in the field of structural inspection or interventional medical treatment.

Development of a biophotonic fiber sensor using direct-taper and anti-taper techniques with seven-core and four-core fiber for the detection of doxorubicin in cancer treatment

Doxorubicin (DOX) is an important drug for cancer treatment, but its clinical application is limited due to its toxicity and side effects. Therefore, detecting the concentration of DOX during treatment is crucial for enhancing efficacy and reducing side effects. In this study, the authors developed a biophotonic fiber sensor based on localized surface plasmon resonance (LSPR) with the multimode fiber (MMF)-four core fiber (FCF)-seven core fiber (SCF)-MMF-based direct-taper and anti-taper structures for the specific detection of DOX. Compared to other detection methods, it has the advantages of high sensitivity, low cost, and strong anti-interference ability. In this experiment, multi-walled carbon nanotubes (MWCNTs), cerium-oxide nanorods (CeO2-NRs), and gold nanoparticles (AuNPs) were immobilized on the probe surface to enhance the sensor's biocompatibility. MWCNTs and CeO2-NRs provided more binding sites for the fixation of AuNPs. By immobilizing AuNPs on the surface, the LSPR was stimulated by the evanescent field to detect DOX. The sensor surface was functionalized with DOX aptamers for specific detection, enhancing its specificity. The experiments demonstrated that within a linear detection range of 0-10 µM, the sensitivity of the sensor is 0.77 nm/µM, and the limit of detection (LoD) is 0.42 µM. Additionally, the probe's repeatability, reproducibility, stability, and selectivity were evaluated, indicating that the probe has high potential for detecting DOX during cancer treatment.

Extending the reach of multi-core fiber via Voronoi constellations with concatenated multilevel coding.

This Letter proposes a novel, to the best of our knowledge, coded modulation scheme for randomly coupled multi-core fiber (RC-MCF) via multidimensional (MD) constellation with concatenated two-level multilevel coding (MLC). In the proposed system, the 16-dimensional (16D) Voronoi constellation (VC), naturally fitting with the 16 degrees of freedom of a four-core fiber (two quadratures, two polarizations, and four cores), is generated by a latticed-based shaping method to provide higher shaping gains. Moreover, combining it with the concatenated two-level MLC can further achieve better performance-complexity trade-off. It is demonstrated by simulation results of long-haul multi-channel RC-MCF transmission that the proposed coded modulation scheme for four-core fiber transmission offers 77% reduction in the number of decoding operations and up to 21% (585 km) reach increase over the conventional bit-interleaved coded modulation scheme for quadrature amplitude modulation.

Ambient temperature monitoring induced by radiation field of four-core fiber optical tweezers

We propose and demonstrate a multi-core fiber optical tweezers system that can automatically monitor ambient temperature. The system uses a four-core fiber frustum cone end to trap small particles such as cells, and four Bragg gratings are written on the cone end of the four-core fiber optical tweezers to monitor the ambient temperature change caused by light radiation at the fiber end of the system. This paper mainly tests the temperature monitoring function of the system when the ambient temperature changes caused by fiber end radiation. Considering that the activity of different cells will be affected when stimulated by the ambient temperature, the monitoring of ambient temperature is particularly important when the operation is carried out for a long time, especially when the radiated laser power is higher than 100 mW. This optical fiber tweezers system provides a better technical solution for the operation and application of living cells through the integration of multi-core fiber grating temperature measurement technology and expands the practical value of optical fiber tweezers.

Study on Characteristics of Coupled-Core Four-Core Fibers With Different Core Pitches

Study on Characteristics of Coupled-Core Four-Core Fibers With Different Core Pitches

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

An axial strain and temperature sensor based on tapered biased four-core fiber (BFCF) operating at the dispersion turning point (DTP) is proposed. The non-adiabatic tapered BFCF (Non-AT BFCF) and adiabatic tapered BFCF (AT BFCF) operating at the DTP were fabricated using the two-step tapering method and the one-step tapering method, respectively, and their axial strain and temperature characteristics were simulated and experimentally investigated. The experimental results show that the maximum sensing sensitivities of Non-AT BFCF are 365.6 pm/με and 2904 pm/°C in the ranges of 0–200 με and 30–70 °C, respectively. The maximum sensing sensitivities of AT-BFCF are 261.14 pm/με and 2280 pm/°C in the ranges of 0–300 με and 30–70 °C, respectively. The sensor is highly sensitive to axial strain and temperature. It has a promising future in measuring physical quantities such as weak strain and temperature.

RI and temperature sensor based on hybrid sensing mechanism of SPR and MZI using a four-core fiber

A dual-parameter sensor based on a hybrid sensing mechanism of surface plasmon resonance (SPR) and Mach–Zehnder interference (MZI) using a four-core fiber (FCF), is proposed and implemented. The designed sensor is fabricated by cascading a sandwich structure of the FCF, multimode fiber and lead-in/out single-mode fiber. The gold-coated FCF as the critical component, enabling the excitation of the SPR and MZI for measuring refractive index (RI) and temperature. The proposed sensor exhibits a high RI sensitivity of 2091 nm/RIU and a temperature sensitivity of 0.0398 nm/°C. The proposed dual-parameter sensor based on FCF provides a new insight for the design of fiber SPR sensor, which can be used to measure multiple physical parameters in various fields such as biochemistry, gene diagnosis, environmental monitoring, and so on.

WaveFlex Biosensor-Using Novel Tri-Tapered-in-Tapered Four-Core Fiber With Multimode Fiber Coupling for Detection of Aflatoxin B1

WaveFlex Biosensor-Using Novel Tri-Tapered-in-Tapered Four-Core Fiber With Multimode Fiber Coupling for Detection of Aflatoxin B1

Cascadable Four-Core Fiber Bragg Gratings Accelerometer for 2-D Low-Frequency Vibration Measurement

Cascadable Four-Core Fiber Bragg Gratings Accelerometer for 2-D Low-Frequency Vibration Measurement

Helical Long-Period Gratings in Four-Core Fiber for Multiparametric Monitoring of Directional Bending, Torsion and Temperature

We demonstrate the multiparametric monitoring of directional bending, torsion, and temperature based on helical long-period gratings (HLPGs) in a triangular four-core fiber (FCF) using CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> laser irradiation. The simulations investigated the stress-relaxing effect of the stress-applying parts due to CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> laser heating. In the experiments, the HLPGs with a period of 435 μm and a period number of 60 induced in FCF have been investigated for multiparametric monitoring. The directional bending sensing characteristics of FCF-HLPGs exhibit that at the curvature ranges A and B, the maximum bending sensitivities are -47.24 and 48.47 dB/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> obtained at -60°, respectively. And their sensitivities show the sine function behavior with curvature directions from -180° to 180°. The torsion sensitivity based on coupling efficiency variation is -0.16%/(rad/m) in the range from -10 to 10 rad/m. The temperature sensitivity based on wavelength variation is 0.123 nm/°C, and the intensity response on temperature can be negligible. The proposed FCF-HLPGs is potential in practical application for multiparametric monitoring.

Field Trial of SDN-Controlled Probabilistic Constellation Shaping Supporting Multiple Rates Over a Coupled-Core Multi-Core Fiber

Space division multiplexing (SDM) is being investigated in support of traffic growth. SDM networks offer multiplexing over space and spectrum dimensions. Probabilistic constellation shaping (PCS) is a solution to optimize spectral efficiency by adapting the constellation of a M-ary quadrature amplitude modulated (QAM) signal to physical layer impairments. At the control plane, in the recent years NETCONF and YANG have been identified as the protocol and the data modeling language, respectively, for the configuration and management of network devices. Significant effort has also been directed to network disaggregation and vendor neutrality: an example is the work done within the OpenConfig consortium. <p xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">In this paper, we present a SDM field trial based on a deployed coupled-core four-core fiber, where a software-defined network (SDN) controller configures probabilistic constellation shaping through NETCONF, by optimizing spectral efficiency either with respect to the path length, or in response to degradations due to soft failures. The NETCONF protocol relies on the OpenConfig YANG data model to configure and manage transceivers. In the field trial the integrated data and control planes are demonstrated with multiple rates (800-850-900-950-1000 Gb/s) for optical reach values ranging from 910 km to 2730 km. Soft failures are also introduced and a characterization of their impact on transmission performance is provided in order to design the recovery strategy deployed by SDN controller. Indeed, depending on the changes in the electrical signal-to-noise ratio, the SDN controller reconfigures the constellation shaping to restore the optical connection affected by the failure with a reduced line rate.

GAWBS Noise in Digital Coherent Transmission

This paper presents recent progress on guided acoustic wave Brillouin scattering (GAWBS) noise in single-core fiber (SCF), multi-core fiber (MCF), and few-mode fiber (FMF). First, we describe theoretical analyses of GAWBS phase noise generated in these various types of fiber. By using three types of SCF, namely ultra-large area fiber (ULAF), standard single-mode fiber (SSMF), and dispersion-shifted fiber (DSF), we show that the GAWBS phase noise depends strongly on the effective core area A <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> . We also describe the GAWBS phase noise in four-core fiber (4CF), where it is shown that GAWBS noise in the off-center core is quite different from that in SCF. Furthermore, we describe the GAWBS phase noise in FMF supporting two LP modes. Then, we compare the GAWBS noise powers induced in SCF, MCF, and FMF. Next, we describe experiments on GAWBS phase noise in various fibers, which agree well with the theory. We also measured and analyzed the GAWBS phase noise correlation between the cores in a 4CF, where it is shown that the correlation between cores strongly depends on the core position. Finally, we describe the influence of GAWBS phase noise on digital coherent transmission. We formulate the GAWBS phase noise based on the Gaussian distribution and evaluate its influence on the BER characteristics in a coherent QAM transmission. We found that it is difficult to realize a transoceanic-class QAM transmission with a QAM multiplicity of higher than 64 even without other impairments. Furthermore, we evaluate the SNR penalty induced by the GAWBS noise in a long-haul transmission by taking account of the amplified spontaneous emission (ASE) and nonlinear interference noise, which are unavoidable in actual systems. The calculated results show that the influence of the GAWBS noise is smaller than the other impairments, but it cannot be neglected in system evaluations.

Structure shape measurement method based on an optical fiber shape sensor

In industry and architecture, real-time and complete measurement of structures has become a research frontier since it is directly related to the safety of life and property. Optical fibers have the potential to monitor constructions due to advantages such as small size, anti-electromagnetic interference, etc. However, existing research on optical fiber sensors pays attention to the sensing fiber itself and ignores the layout of the optical fibers. As a result, currently available fiber sensors are only suitable for monitoring one-dimensional rigid structures such as surgical robots and puncture needles. They may face challenges when measuring the freeform surfaces encountered in industrial and architectural scenarios. In this paper, a cross-orthogonal measurement method based on optical fiber shape sensors is proposed to meet the shape measurement requirements of freeform surfaces. The cross-orthogonal network allows global measurement and performs surface reconstructions more easily as compared to single-fiber arrays. It also divides the sensing fiber into several segments that are reconstructed separately (with different initial frames), avoiding the cumulative error at the end of the sensing fiber. Results of verification experiments using four-core fibers indicate that the presented method can improve measurement accuracy.

3-D Parallel Fiber Bragg Gratings Bending Sensor Based on Single-Channel Measurement

A bending sensor is proposed to demodulate the multichannel bending signals of multicore fiber (MCF) to single-channel signals by using the phase mask method combined with the thermal diffusion technique (TDT). A four-core fiber (FCF) bending sensor was fabricated. Each fiber core of the FCF had different resonant wavelengths through the method of core-by-core inscribed fiber Bragg gratings (FBGs) at the same axial position. The FCF was coupled with a single-mode fiber (SMF) by the TDT method. Finally, the single-channel measurement of the 3-D parallel FCF FBGs signals was realized. The FBGs on four cores of FCF were equivalent to the FBGs on two orthogonal cores by a different operation. The experimental results showed that the maximum bending sensitivities of the equivalent FBGs were 187.2 and −192.6 pm/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}^{-{1}}$ </tex-math></inline-formula> , respectively. This sensor realized single-channel demodulation of MCF signals with the elimination of the crosstalk caused by temperature and strain. The proposed sensor fabrication technology with high integration, high sensitivity, and reduced crosstalk, is expected to be applied in the field of 3-D shape measurement or wearable artificial electronics.