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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Plasma-Mirror FROG using Liquid-Sheet Water Jet in Ultraviolet Region
摘要： Mobile fronthaul is an important network segment that bridges wireless baseband units and remote radio units to support cloud radio access network. We review recent progresses on the use of frequency-division multiplexing to achieve highly bandwidth-efficient mobile fronthaul with low latency. We present digital signal processing (DSP) techniques for channel aggregation and deaggregation, frequency-domain windowing, adjacent channel leakage ratio reduction, and synchronous transmission of both the I/Q waveforms of wireless signals and the control words (CWs) used for control and management purposes. In a proof-of-concept experiment, we demonstrate the transmission of 48 20-MHz LTE signals with a common public radio interface (CPRI) equivalent data rate of 59 Gb/s, achieving a low round-trip DSP latency of <2 μs and a low mean error-vector magnitude (EVM) of ～2.5% after fiber transmission. In a follow-up experiment, we further demonstrate the transmission of 32 20-MHz LTE signals together with CPRI-compliant CWs, corresponding to a CPRI-equivalent data rate of 39.32 Gb/s, in single optical wavelength channel that requires an RF bandwidth of only ～1.6 GHz. After transmission over 5-km standard single-mode fiber, the CWs are recovered without error, while the LTE signals are recovered with an EVM of lower than 3%. Applying this technique to future 5G wireless networks with massive multiple-input multiple-output is also discussed. This efficient mobile fronthaul technique may find promising applications in future integrated fiber/wireless access networks to provide ultrabroadband access services.
关键词： fifth-generation (5G),frequency-division multiplexing (FDM),common public radio interface (CPRI),Cloud radio access network (C-RAN),optical fiber transmission,mobile fronthaul
更新于2025-09-19 17:13:59
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Photothermal Effect in Plasmonic Nanotip for LSPR Sensing
摘要： The influence of heat generation on the conventional process of LSPR based sensing has not been explored thus far. Therefore, a need exists to draw attention toward the heat generation issue during LSPR sensing as it may affect the refractive index of the analyte, leading to incorrect sensory conclusions. This manuscript addresses the connection between the photo-thermal effect and LSPR. We numerically analyzed the heat performance of a gold cladded nanotip. The numerical results predict a change in the micro-scale temperature in the microenvironment near the nanotip. These numerical results predict a temperature increase of more than 20 K near the apex of the nanotip, which depends on numerous factors including the input optical power and the diameter of the fiber. We analytically show that this change in the temperature influences a change in the refractive index of the microenvironment in the vicinity of the nanotip. In accordance with our numerical and analytical findings, we experimentally show an LSPR shift induced by a change in the input power of the source. We believe that our work will bring the importance of temperature dependence in nanotip based LSPR sensing to the fore.
关键词： refractive index,electromagnetic heating,localized surface plasmon resonance,optical fiber sensors,nanotip
更新于2025-09-19 17:13:59
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A novel periodically tapered structure-based gold nanoparticles and graphene oxide a?? Immobilized optical fiber sensor to detect ascorbic acid
摘要： This work presents a study, analysis, design, and characterization of a localized surface plasmon resonance (LSPR) based ascorbic acid (AA) sensor with improved sensitivity compared to those already reported. Various multi-tapered (four, five, and eight tapered) optical fiber sensors (OFSs) have been developed and characterized in this study. Along with these, different nanomaterials (NMs), such as gold nanoparticles (AuNPs) and graphene oxide (GO), are immobilized over the bare probe. Further, NMs immobilized probes are functionalized with ascorbate oxidase. The AuNPs are well studied in the past with the variation in size, shape and surface functionalization and have been found to be well-suited NMs for biosensing applications. On the other hand, GO-based material is equally promising in the nanostructure-based optical sensing due to their broad surface area, high electrical conductivity, good chemical stability, and excellent mechanical behavior. The performance parameters of the proposed sensor, such as sensitivity (8.3 nm/mM), correlation correlator (0.9724), and limit of detection (51.94 μM) are greatly improved over the previous designs. A wide range of characterization and validation of NMs immobilized structures are reported here. It indicates a great potential in the practical implementation of LSPR based OFSs for routine diagnostics.
关键词： Multi-tapered optical fiber sensor,Ascorbic acid,Gold nanoparticles,Ascorbate oxidase,Graphene oxide
更新于2025-09-19 17:13:59
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Selective Ultrasensitive Optical Fiber Nanosensors Based on Plasmon Resonance Energy Transfer
摘要： The facet of optical fibers coated with nanostructures enable the development of ultraminiature and sensitive (bio)chemical sensors. The reported sensors until now lack of specificity and the fabrication methods offer poor reproducibility. Here, we demonstrate that by transforming the facet of conventional multimode optical fibers onto plasmon resonance energy transfer (PRET) antenna surfaces the specificity issues may be overcome. To do so, a low cost chemical approach was developed to immobilize gold nanoparticles on the optical fiber facet in a reproducible and controlled manner. Our nanosensors are highly selective as PRET is a nanospectroscopic effect that only occurs when the resonant wavelength of the nanoparticles matches that of the target parameter. As an example, we demonstrate the selective detection of picomolar concentrations of copper ions in water. Our sensor is 1,000 times more sensitive than state of the art technologies. An additional advantage of our nanosensors is their simple interrogation; it comprises of a low-power light emitting diode, a multimode optical fiber coupler, and a miniature spectrometer. We believe that the PRET-based fiber optic platform reported here may pave the way of the development of a new generation of ultra-miniature, portable, and hypersensitive and selective (bio)chemical sensors.
关键词： plasmonics,chemosensor,nanoparticles,optical fiber,metal ion
更新于2025-09-19 17:13:59
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Crack monitoring in reinforced concrete beams by distributed optical fiber sensors
摘要： This paper investigates the use of distributed optical fiber sensors (DOFS) based on Optical Frequency Domain Reflectometry of Rayleigh backscattering for Structural Health Monitoring purposes in civil engineering structures. More specifically, the results of a series of laboratory experiments aimed at assessing the suitability and accuracy of DOFS for crack monitoring in reinforced concrete members subjected to external loading are reported. The experiments consisted on three-point bending tests of concrete beams, where a polyamide-coated optical fiber sensor was bonded directly onto the surface of an unaltered reinforcement bar and protected by a layer of silicone. The strain measurements obtained by the DOFS system exhibited an accuracy equivalent to that provided by traditional electrical foil gauges. Moreover, the analysis of the high spatial resolution strain profiles provided by the DOFS enabled the effective detection of crack formation. Furthermore, the comparison of the reinforcement strain profiles with measurements from a digital image correlation system revealed that determining the location of cracks and tracking the evolution of the crack width over time were both feasible, with most errors being below ±3 cm and ±20 mm, for the crack location and crack width, respectively.
关键词： crack monitoring,structural health monitoring,damage assessment,reinforced concrete,Concrete beams,distributed optical fiber sensors
更新于2025-09-19 17:13:59
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Development of measurement system for microstructures using an optical fiber probe: improvement of measurable region and depth
摘要： The precise measurement of microstructures and other micron-sized materials has garnered considerable interest in recent years. However, a limited measurement region and unavailability of miniaturized probes are the major issues in the realization of such systems. In this study, we have presented a system for microstructures based on a small-diameter optical fiber probe. In the improved measurement system, the prism was installed near the stylus shaft to expand the measurable region and depth. It means that there is no limitation on the width of the measurement object. The standard deviation of the repeatability of the point measurement in the X-, Y-, and Z-directions were 31, 38, and 19 nm, respectively. A pin gauge with a diameter of 100 μm was measured 10 times for assessing the repeatability of measurements in the X-, and Y-directions. The standard deviation of diameter in these measurements was 25 nm. A step height standard with a calibrated height of 189.6 nm was measured 10 times for assessing the repeatability of measurement in the Z-direction. The average height in these measurements was obtained as 200.2 nm with the expanded uncertainty of 49.3 nm (Coverage factor k = 2). We confirmed this system enabled accurate measurement in the X-, Y- and Z-directions.
关键词： Probe,Microstructure measurement,Repeatability,Optical fiber
更新于2025-09-19 17:13:59
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Deep learning method for detection of structural microcracks by Brillouin scattering based distributed optical fiber sensors
摘要： Brillouin scattering (BS)–based distributed optical fiber sensors (DOFS) provide distributed sensing capabilities by monitoring the strain along entire segments of structures. Large cracks, such as those with large crack opening displacements (COD) can be detected by strain peaks or singularities along the measurement length of distributed sensors. Microcracks do not provide visible pronounced local peaks along the length of measured distributed strains. The peaks corresponding to microcracks are submerged within the measurement noise due to low signal-to-noise ratio (SNR) of BS systems. Deep learning (DL) methods have the potential to automatically extract feature representations from data exhibiting lower SNRs, and improve the crack detection sensitivity of the BS-based DOFS. Development of the proposed DL method includes construction of model architecture, design of a training algorithm and the detection process. A 15-m-long wide-flange steel beam with artificial defects is built and employed in this study. A comprehensive experimental program is undertaken in order to train, validate and test the generality of the proposed DL method. Experimental results demonstrate that the DL method is capable of extracting highly discernable microcrack features from the distributed strains, and distinguish the crack-induced local peaks from the noise. Microcracks with CODs as small as 23 microns are accurately detected in the present work.
关键词： Structural health monitoring,optical fiber sensors,Brillouin Scattering,crack detection,deep learning
更新于2025-09-19 17:13:59
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A Refractive Index Sensor Based on H-Shaped Photonic Crystal Fibers Coated with Ag-Graphene Layers
摘要： An Ag‐graphene layers‐coated H‐shaped photonic crystal fiber (PCF) surface plasmon resonance (SPR) sensor with a U‐shaped grooves open structure for refractive index (RI) sensing is proposed and numerically simulated by the finite element method (FEM). The designed sensor could solve the problems of air‐holes material coating and analyte filling in PCF. Two big air‐holes in the x‐axis produce a birefringence phenomenon leading to the confinement loss and sensitivity of x‐polarized light being much stronger than y‐polarized. Graphene is deposited on the layer of silver in the grooves; its high surface to volume ratio and rich π conjugation make it a suitable dielectric layer for sensing. The effect of structure parameters such as air‐holes size, U‐shaped grooves depth, thickness of the silver layer and number of graphene layers on the sensing performance of the proposed sensor are numerical simulated. A large analyte RI range from 1.33 to 1.41 is calculated and the highest wavelength sensitivity is 12,600 nm/RIU. In the linear RI sensing region of 1.33 to 1.36; the average wavelength sensitivity we obtained can reach 2770 nm/RIU with a resolution of 3.61 × 10?5 RIU. This work provides a reference for developing a high‐sensitivity; multi‐parameter measurement sensor potentially useful for water pollution monitoring and biosensing in the future
关键词： H‐shaped optical fiber,graphene,liquid refractive index,photonic crystal fibers,surface plasmon resonance
更新于2025-09-19 17:13:59
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Secure 100 Gb/s IMDD Transmission Over 100 km SSMF Enabled by Quantum Noise Stream Cipher and Sparse RLS-Volterra Equalizer
摘要： In this paper, we have experimentally demonstrated a secure 100 Gb/s intensity-modulation and direct-detection transmission over 100 km standard single-mode fiber (SSMF) based on quantum noise stream cipher (QNSC) for the first time. The original 4-level pulse-amplitude modulation (PAM4) data is mapped to M-level data sequence randomly, and quantum noise such as the generated amplified spontaneous emission noise and the shot noise in the channel can mask these adjacent signal levels. The legitimate receiver needs to distinguish not M-level encrypted data but 4-level data with the shared key. In our scheme, a calculated detection failure probability of 98.72% is achieved. Apparently, more quantum noise contributes to higher security but the worse signal to noise ratio. To balance algorithm complexity, transmission performance and security performance, a sparse regularization based on recursive least square (RLS) algorithm is proposed and firstly used in Volterra equalizer. To eliminate the power fading induced by fiber dispersion, a dual-drive Mach-Zehnder modulator is used to achieve single-sideband modulation, and no dispersion compensation is required. By these means, 100Gb/s PAM4-QNSC signal transmission over 100 km SSMF with the bit error rate (BER) below the 7% overhead hard-decision forward error correction threshold of 3.8x10-3 is achieved, and >59% complexity reduction of Volterra equalizer is realized. Moreover, the measured BER of 150 Gb/s PAM8-QNSC signal transmission over 50 km SSMF could go below the 20% overhead soft-decision forward error correction threshold of 2.0×10-2. The results validate that the proposed scheme is effective to realize low-cost, high-speed (>100 Gb/s), and secure optical fiber transmission in the data center.
关键词： quantum noise cipher stream,Optical fiber communication,sparse RLS-Volterra equalizer
更新于2025-09-19 17:13:59
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Experimental Study on the Movement and Evolution of Overburden Strata Under Reamer-Pillar Coal Mining Based on Distributed Optical Fiber Monitoring
摘要： Focusing on the deterioration of the surface ecological environment caused by large-scale exploitation of the Jurassic coal field in northern Shaanxi, the three-dimensional similar material test model is made to simulate the extraction of shallow coal seam. Using Brillouin optical time-domain analysis (BOTDA) optical fiber distributed sensing technology, this paper studied the strain distribution rule and movement characteristics of strata under reamer-pillar mining, analyzed the stability of the remaining coal pillars in the mining area, and obtained the strain contour graph of strata through calculations. The research result shows that the deformation of coal pillars in a safety-critical state under reamer-pillar mining experiences three stages. The stratum deformation is distributed in the shape of a pyramid with the mining area as the center. On the basis of the strain distribution of strata, the settlement curve and subsidence curve of strata deformation are determined to obtain the rupture angle and angle of draw. After being compared with the measured data, the angle values are almost the same.
关键词： BOTDA,reamer-pillar mining,stratum movement,optical fiber sensing,shallow coal seam
更新于2025-09-19 17:13:59