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Fabrication of gold nanorod arrays on a cylindrical surface of optical fibers by using in-situ electrodeposition
摘要： Optical fiber is an excellent light-coupled substrate, which has the characteristics of large a length-diameter ratio with a cylindrical surface. Recently, various methods have been reported in order to improve the ability of local optical fields. In particular, methods aimed to address the efficient coupling and optical resonances by modifying metal nanostructures on the light-coupled substrate have been developed. However, existing methods are largely applicable to planar or tip substrates, and it remains a significant challenge to prepare metal nanostructures on a cylindrical substrate. In this study, we proposed a novel strategy to fabricate gold nanorods arrays (AuNRs) by electrodepositing them in anodized aluminum oxide (AAO) templates on the cylindrical surface of optical fibers. Briefly, AAO templates were prepared in-situ by using a constant current density secondary oxidation method on the cylindrical surface of optical fibers, and then the AuNRs were in-situ deposited in the AAO templates by electrodeposition. The features of the AuNRs such as diameter, nanorod pitch, and height could be easily regulated by adjusting the parameters of electrodeposition and the anode oxidation. The SEM images demonstrates that AuNRs exhibit a satisfactory consistency with a uniform diameter and favorable self-supporting properties. The relationships between the current density, pore diameter and pore distribution were explored, combined with the voltage-time curve during anodic oxidation. Furthermore, the surface plasmon resonance (SPR) optical properties of the AuNRs on the cylindrical surface were analyzed using the Finite-difference Time-domain Algorithm (FDTD) method. Results suggest that this alternative in-situ electrodeposition strategy has the potentials to be applied to SPR optical fiber sensing.
关键词： Gold nanorods arrays,Finite-difference time-domain algorithm,In-situ electrodeposition,Cylindrical surface of optical fibers,Anodized aluminum oxide templates
更新于2025-09-19 17:13:59
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Transient and Steady-State Radiation Response of Phosphosilicate Optical Fibers: Influence of H2 Loading
摘要： The radiation response of a phosphorus-doped multimode optical fiber is investigated under both transient (pulsed X-rays) and steady state (γ-rays and X-rays) irradiations. The influence of a H2 pre-loading on the fiber radiation induced attenuation (RIA) in the 300 nm - 2000 nm wavelength range has been characterized. To better understand the impact of this treatment, online behaviors of fiber samples containing different amounts of gas are compared from glass saturation (100%) to less than 1%. In addition to these in situ experiments, additional post-irradiation spectroscopic techniques have been performed such as electron paramagnetic resonance or luminescence measurements to identify the different point defects responsible for the induced losses and their H2 dependence. All our data at room temperature (RT) highlight a strong positive impact of H2, even at very low concentrations, on the RIA. Hydrogen quickly passivates (t<1 s) most of the defects responsible for the visible – near-IR RIA, mainly phosphorus oxygen hole centers (POHC) and P1 defects. However, one year after the H2-loading at RT or when operating at liquid nitrogen temperature, the RIA levels of the not-treated and H2-loaded fiber become comparable. The obtained results provide a better understanding of the potential and limitations of H2-loading treatment to design radiation hardened fiber links.
关键词： temperature,point defects,phosphorus,H2-loading,X-rays,radiation effects,optical fibers,pulsed X-rays
更新于2025-09-19 17:13:59
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Thermal Poling of Optical Fibers: A Numerical History
摘要： This review gives a perspective of the thermal poling technique throughout its chronological evolution, starting in the early 1990s when the first observation of the permanent creation of a second order non-linearity inside a bulk piece of glass was reported. We then discuss a number of significant developments in this field, focusing particular attention on working principles, numerical analysis and theoretical advances in thermal poling of optical fibers, and conclude with the most recent studies and publications by the authors. Our latest works show how in principle, optical fibers of any geometry (conventional step-index, solid core microstructured, etc) and of any length can be poled, thus creating an advanced technological platform for the realization of all-fiber quadratic non-linear photonics.
关键词： thermal poling,numerical analysis,non-linear photonics,optical fibers
更新于2025-09-19 17:13:59
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Structural and spectroscopic studies on the concentration dependent erbium doped lithium bismuth boro tellurite glasses for optical fiber applications
摘要： High gain and better optical properties are the key requirement for the optical fibers and amplifiers to meet the current technological demand. In this regard, in the present investigation, erbium doped lithium bismuth boro tellurite glasses are prepared using melt-quenching technique. The prepared glasses were extensively characterized through, XRD, DSC, UV–Vis-NIR and also Luminescence and Decay techniques to study the concentration dependent structural, optical and luminescence properties. Prepared glasses are amorphous in nature and the corresponding band gap energy decreases with erbium concentration indicates increase of metallicity of the glasses. FTIR studies show different vibration modes majorly borate groups. In addition, Judd-Oflet theory is employed to derive different optical parameters such as intensity parameters, oscillatory strength, branching ratio, stimulated emission cross section and time decay to validate the experimental results of prepared glasses towards optical fiber applications. Estimated values of Stimulated emission, effective band width and gain band width values found higher when compared with other host glasses. Results also show that, 100% branching ratio is obtained for the highest intense peaks corresponds to the transition 4I13/2 → 4I15/2 in NIR luminescence spectra for 1.53 μm broad band. For power dependent 980 nm excitation, up-conversion spectra shows two transitions, namely 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 at 541 and 655 nm corresponds to green and red emission respectively. From the McCumber’s theory, the absorption and emission cross section more comaprable values are obtained for 1 mol% erbium doped glass. About 40% population inversion is obtained with C band from 1500 to 1550 nm. The results suggests that, the prepated glasses are the potential candidates for optical fiber applications.
关键词： Band gap energy,Judd-Oflet,NIR emission,Optical fibers,Boro-tellurite glasses
更新于2025-09-19 17:13:59
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Distributed Fiberoptic Sensor for Simultaneous Humidity and Temperature Monitoring Based on Polyimide-Coated Optical Fibers
摘要： Along temperature, humidity is one of the principal environmental factors that plays an important role in various application areas. Presented work investigates possibility of distributed fiberoptic humidity monitoring based on humidity-induced strain measurement in polyimide (PI)-coated optical fibers. Characterization of relative humidity (RH) and temperature response of four different commercial PI- and one acrylate-coated fiber was performed using optical backscattering reflectometry (OBR). The study addresses issues of temperature-humidity cross-sensitivity, fiber response stability, repeatability, and the influence of annealing. Acrylate-coated fiber exhibited rather unfavorable nonlinear RH response with strong temperature dependence, which makes it unsuitable for humidity sensing applications. On the other hand, humidity response of PI-coated fibers showed good linearity with fiber sensitivity slightly decreasing at rising temperatures. In the tested range, temperature sensitivity of the fibers remained humidity independent. Thermal annealing was shown to considerably improve and stabilize fiber RH response. Based on performed analysis, a 20 m sensor using the optimal PI-coated fibers was proposed and constructed. The sensor uses dual sensing fiber configuration for mutual decoupling and simultaneous measurement of temperature and RH variations. Using OBR, distributed dual temperature-RH monitoring with cm spatial resolution was demonstrated for the first time.
关键词： fiberoptic sensors,distributed humidity sensing,polyimide-coated optical fibers,optical frequency-domain reflectometry,dual sensing
更新于2025-09-16 10:30:52
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Investigation of UV Irradiation Response of Optical Fiber Sensors for Radiation Dosimetry
摘要： In this work, the investigation of radiation response for modified cladding multimode optical fibres exposed to UV radiation (N2 Laser) in terms of Radiation-Induced Attenuation (RIA) had been presented. The optical fibres were tapered to 65 and 60 μm then dipped into (5wt % of Germanium to modify the cladding region. By exposing these fibres to different energies of UV irradiation, the transmission spectra were online monitored and recorded every ten seconds to analyze the attenuation changes with the increasing of the radiation dose. The experimental results revealed two points: the first point is that the sensor undergoes the RIA effect which is resulted from the interaction between the radiation and the dopant material, and the second point shows that the sensitivity increases as the diameter of the sensor decrease. From these outcomes, we can conclude that such a sensor can be employed in different dosimetry applications.
关键词： Radiation Dosimeters,Radiation-Induced Absorption,Optical Fiber Sensors,Germanium Doped Optical Fibers
更新于2025-09-16 10:30:52
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Novel Gd3+-doped silica-based optical fiber material for dosimetry in proton therapy
摘要： Optical fibers hold promise for accurate dosimetry in small field proton therapy due to their superior spatial resolution and the lack of significant Cerenkov contamination in proton beams. One known drawback for most scintillation detectors is signal quenching in areas of high linear energy transfer, as is the case in the Bragg peak region of a proton beam. In this study, we investigated the potential of innovative optical fiber bulk materials using the sol-gel technique for dosimetry in proton therapy. This type of glass is made of amorphous silica (SiO2) and is doped with Gd3+ ions and possesses very interesting light emission properties with a luminescence band around 314 nm when exposed to protons. The fibers were manufactured at the University of Lille and tested at the TRIUMF Proton Therapy facility with 8.2–62.9 MeV protons and 2–6 nA of extracted beam current. Dose-rate dependence and quenching were measured and compared to other silica-based fibers also made by sol-gel techniques and doped with Ce3+ and Cu+. The three fibers present strong luminescence in the UV (Gd) or visible (Cu,Ce) under irradiation, with the emission intensities related directly to the proton flux. In addition, the 0.5 mm diameter Gd3+-doped fiber shows superior resolution of the Bragg peak, indicating significantly reduced quenching in comparison to the Ce3+ and Cu+ fibers with a Birks’ constant, kB, of (0.0162 ± 0.0003) cm/MeV in comparison to (0.0333 ± 0.0006) cm/MeV and (0.0352 ± 0.0003) cm/MeV, respectively. To our knowledge, this is the first report of such an interesting kB for a silica-based optical fiber material, showing clearly that this fiber presents lower quenching than common plastic scintillators. This result demonstrates the high potential of this inorganic fiber material for proton therapy dosimetry.
关键词： Bragg peak,dosimetry,Gd3+-doped silica,optical fibers,quenching,sol-gel technique,proton therapy
更新于2025-09-16 10:30:52
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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) - Polarization Organisation Hidden in the Middle Point of an Optical Fiber
摘要： Since the pioneering studies on polarization dynamics of two counter-propagating beams in nonlinear optical fibers, different processes of polarization attraction have been identified in isotropic fiber, but also in highly, weakly and randomly birefringent fibers. In this framework, the polarization attraction requires a fully polarized pump wave, which plays the role of a natural attractor for an arbitrary polarized incoming beam. Subsequently, this phenomenon has been observed using a single wave interacting with its own back-reflected wave in a feedback loop configuration. Here, we report a new configuration of polarization self-organization with two uncorrelated arbitrary polarized waves that occurs in the middle point of an optical isotropic fiber. The state of polarization (SOP) of the two counterpropagating waves evolves and fluctuates over the surface of the Poincaré sphere with a coherence time τc. During the propagation, the SOP is deeply modified by the nonlinear interaction: While the injected SOPs fluctuate all over the Poincaré spheres, the SOPs in the middle point of the fiber are attracted toward the poles of the spheres, which correspond to the circular polarization states of the fields. Then both waves recover a random state at their corresponding fiber outputs. This effect has been demonstrated experimentally considering 256 randomly distributed initial pulses in an 200-m long isotropic fiber.
关键词： coherence time,optical fibers,polarization attraction,Poincaré sphere,polarization dynamics
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Economical Solution for Cladding Etched Optical Fibers
摘要： We demonstrate an economical wet etching solution for optical fibers using glass etching cream. The etching performance and surface quality on optical fibers are investigated. The solution offers good controllability and repeatable outcomes.
关键词： optical fibers,glass etching cream,Chemical wet etching
更新于2025-09-16 10:30:52
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Depth-resolved fiber photometry with a single tapered optical fiber implant
摘要： Fiber photometry is increasingly utilized to monitor fluorescent sensors of neural activity in the brain. However, most implementations are based on flat-cleaved optical fibers that can only interface with shallow tissue volumes adjacent to the fiber. We exploit modal properties of tapered optical fibers (TFs) to enable light collection over an extent of up to 2 mm of tissue and multisite photometry along the taper. Using a single TF, we simultaneously observed distinct dopamine transients in dorsal and ventral striatum in freely moving mice performing a simple, operant conditioning task. Collection volumes from TFs can also be engineered in both shape and size by microstructuring the nonplanar surface of the taper, to optically target multiple sites not only in the deep brain but, in general, in any biological system or organ in which light collection is beneficial but challenging because of light scattering and absorption.
关键词： neural activity,tapered optical fibers,dopamine transients,fiber photometry,multisite photometry
更新于2025-09-16 10:30:52