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An interferometric structure with a dual-resonance long period grating for strain sensing
摘要： Spectral characteristics and amplitude tunability of a long period grating with a dual-resonance inside fiber loop mirror are studied in terms of applied stress caused by elongation. Inserting the polarization controller between grating and part of polarization maintaining fiber in the loop structure enables tuning of resonance and interferometric peaks. The maximum sensitivity of demonstrated sensor is of 1.943 dB/mε for the range of 1.1–4.4 mε. Combination of these two optical components allows to measure strain in a wider range comparing with sensors based on standard long period grating.
关键词： Fiber loop mirror,Polarization controller,Polarization maintaining fiber,Strain sensor,Long period grating
更新于2025-09-23 15:23:52
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Surface plasmon resonance on blue GaN-based VCSEL with Al-grating
摘要： Based on the research of surface plasmon (SP) applied to Vertical-Cavity Surface-Emitting Lasers (VCSEL), we proposed a new 465 nm GaN-based VCSEL to enhance illumination by deposit Al rectangular grating onto p-i-n layer. Meanwhile, an increase in the e?ective radiated power was obtained by the control of a surface plasmon mode, which depends strongly on the structural parameters such as material, period, depth and dipole location. Compared to conventional structure, we have a 30% improvement in e?ective radiated power. Such advantages make surface Al-grating be an alternative low-cost and simple technique used in SP-coupled VCSEL for the blue range.
关键词： Finite-di?erence time-domain method,Metal grating,Surface plasmon,Vertical-cavity surface-emitting laser (VCSEL)
更新于2025-09-23 15:23:52
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Metrology of Nanostructures by Tomographic Mueller-Matrix Scatterometry
摘要： The development of necessary instrumentation and metrology at the nanoscale, especially fast, low-cost, and nondestructive metrology techniques, is of great significance for the realization of reliable and repeatable nanomanufacturing. In this work, we present the application of a homemade novel optical scatterometer called the tomographic Mueller-matrix scatterometer (TMS), for the measurement of photoresist gratings. The TMS adopts a dual rotating-compensator configuration and illuminates the nanostructure sequentially under test conditions by a plane wave, with varying illumination directions and records. For each illumination direction, the polarized scattered field along various directions of observation can be seen in the form of scattering Mueller matrices. That more scattering information is collected by TMS than conventional optical scatterometry ensures that it achieves better measurement sensitivity and accuracy. We also show the capability of TMS for determining both grating pitch and other structural parameters, which is incapable by current zeroth-order methods such as reflectometry- or ellipsometry-based scatterometry.
关键词： inverse scattering,ellipsometry,pitch measurement,diffraction grating,scatterometry,Mueller matrix
更新于2025-09-23 15:23:52
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AIP Conference Proceedings [Author(s) 4TH ELECTRONIC AND GREEN MATERIALS INTERNATIONAL CONFERENCE 2018 (EGM 2018) - Bandung, Indonesia (27–28 July 2018)] - Design and analysis of fiber Bragg grating tunable filter utilizing thermal technique
摘要： In this paper a tunable filter based on fiber Bragg grating (FBG) utilizing thermal technique is theoretically investigated and experimentally validated. According to the results, a tuning range is achieved about 1.5 nm in C-band region. While, for L-band region the wavelength shift is slightly greater than in the C-band region about 1.6 nm. This shifting is due to changing in thermo-optic and thermal expansion of fiber, which causes changing in refractive index and then Bragg wavelength. The experimental validation is done at wavelength 1552.7 nm, the tunability is about 1.2428 nm when the temperature is varied from 21°C to 61°C.
关键词： thermal expansion,fiber Bragg grating,thermo-optic effect,thermal technique,tunable filter
更新于2025-09-23 15:23:52
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Fiber Bragg grating-based experimental and numerical investigations of CO <sub/>2</sub> migration front in saturated sandstone under subcritical and supercritical conditions
摘要： Carbon dioxide (CO2) can be at risk of leakage during its storage in deep saline aquifers due to stress field changes in the reservoir. The aim of this study was to investigate the effects of CO2 injection pressure on dynamic strain response of the reservoir and the CO2 migration process. A series of core flooding experiments was performed with the-state-of-art fiber Bragg grating sensors. The results show that the surface strain response was linearly correlated with CO2 injection pressure. Carbon dioxide migration velocity can be estimated from the strain response time differences among three gratings. The migration velocity of supercritical CO2 is higher than that of liquid CO2 but lower than gaseous CO2. Finally, numerical simulation was applied to model the CO2 migration process and the simulated values were compatible with those of experiments.
关键词： reservoir sandstone,core flooding,CO2 geological storage,CO2 migration front,fiber Bragg grating,strain response
更新于2025-09-23 15:23:52
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Torsion‐dependent spectral response of long‐period fiber grating based on electric arc technique with axial rotation of the fiber
摘要： We present a novel technique for manufacturing a long-period fiber grating (LPFG) with enhanced torsion sensitivity based on electric arc technique. The proposed method rotates the fiber around its axis of rotation at each electric arc discharge. We experimentally investigated the torsion-dependent spectral response of the produced grating and the results showed that an enhanced linear torsion sensitivity up to 0.197 nm/(rad/m) was achieved, which is higher than that of the conventional arc-induced LPFGs.
关键词： long-period fiber grating,torsion sensing,electric arc discharge
更新于2025-09-23 15:23:52
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A novel fiber Bragg grating system for eye tracking
摘要： Eye movement evaluation is vital for diagnosis of various ophthalmological and neurological disorders. The present study proposes a novel, noninvasive, wearable device to acquire the eye movement based on a Fiber Bragg Grating (FBG) Sensor. The proposed Fiber Bragg Grating Eye Tracker (FBGET) can capture the displacement of the eyeball during its movements in the form of strain variations on a cantilever. The muscular displacement generated by the eyeball over the lower eyelid, by its swiveling action while moving the gaze on a target object, is converted into strain variations on a cantilever. The developed FBGET is investigated for dynamic tracking of the eye- gaze movement for various actions of the eye such as fixations, saccades and main sequence. This approach was validated by recording the eye movement using the developed FBGET as well as conventional camera-based eye tracker methodology simultaneously. The experimental results demonstrate the feasibility and the real-time applicability of the proposed FBGET as an eye tracking device. In conclusion, the present study illustrates a novel methodology involving displacement of lower eyelid for eye tracking application along with the employment of FBG sensors to carry out the same. The proposed FBGET can be utilized in both clinical and hospital environment for diagnostic purposes owing to its advantages of wear-ability and ease of implementation making it a point of care device
关键词： Eye Tracker,Fiber Bragg Grating Sensor,Eye muscular movement detection
更新于2025-09-23 15:23:52
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[IEEE 2018 3rd International Conference On Internet of Things: Smart Innovation and Usages (IoT-SIU) - Bhimtal (2018.2.23-2018.2.24)] 2018 3rd International Conference On Internet of Things: Smart Innovation and Usages (IoT-SIU) - Fiber Bragg Grating basedLandslide Early Warning System
摘要： Landslides are natural hazards which are known to cause loss of life and infrastructural damage. Landslide Early Warning System (LEWS) is intended to predict the occurrence of the landslide which provides ample time to initiate necessary protective measures. In the present study, a Fiber Bragg Grating (FBG) sensor based vibration sensor which can acquire the seismic vibrations is proposed as an LEWS. The proposed Fiber Bragg Grating Vibration Sensor (FBGVS) works on a specially designed cantilever structure, through which the seismic vibrations can be obtained in the form of strain variations on the cantilever. The strain variations over the cantilever will be acquired by the FBG sensor bonded over it. The cantilever is specially designed such that the strain sensitivity of the FBGVS is enhanced, by the appending of torsional strain along with the axial strain. Experimental trials have been carried out which prove the efficacy of the FBGVS to acquire the seismic vibrations. FBGVS acts as the sensing element for an IoT system to ensure the landslide warning signal is transmitted to all remote locations, effectively making an efficient LEWS.
关键词： Fiber Bragg grating sensor,Landslide Early Warning System,Fiber Bragg Grating Vibration Sensor
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Chengdu, China (2018.5.7-2018.5.11)] 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Grating Lobe Suppression of Planar Array with Large Inter-Element Spacing by Using Genetic Algorithm
摘要： In this paper, a method using genetic algorithm to suppress the grating lobe of a wideband planar array is presented. With the alteration of operating frequency point, the electrical size of distance between two adjacent elements will change thereupon. This approach achieves the suppression of grating lobe at high operating frequency point, whose highest sidelobe level is around -10 dB, with little influence to array’s radiation characteristic of lower frequency point. For this approach’s practicability, simple dipole antenna is adopted as the array’s element to check out whether the approach keeps validity by simulation.
关键词： Grating lobe suppression,distance optimization,sparse array,genetic algorithm
更新于2025-09-23 15:22:29
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Fibre Bragg grating sensor applications for structural health monitoring
摘要： Purpose – Structural health monitoring (SHM) has become an attractive subject in aerospace engineering ?eld considering the opportunity to avoid catastrophic failures by detecting damage in advance and to reduce maintenance costs. Fibre Bragg Grating (FBG) sensors are denoted as one of the most promising sensors for SHM applications as they are lightweight, immune to electromagnetic effects and able to be embedded between the layers of composite structures. The purpose of this paper is to research on and demonstrate the feasibility of FBG sensors for SHM of composite structures. Design/methodology/approach – Applications on thin composite beams intended for SHM studies are presented. The sensor system, which includes FBG sensors and related interrogator system, and manufacturing of the beams with embedded sensors, are detailed. Static tension and torsion tests are conducted to verify the effectiveness of the system. Strain analysis results obtained from the tests are compared with the ones obtained from the ?nite element analyses conducted using ABAQUS? software. In addition, the comparison between the data obtained from the FBG sensors and from the strain gauges is made by also considering the noise content. Finally, fatigue test under torsion load is conducted to observe the durability of FBG sensors. Findings – The results demonstrated that FBG sensors are feasible for SHM of composite structures as the strain data are accurate and less noisy compared to that obtained from the strain gauges. Furthermore, the convenience of obtaining reliable data between the layers of a composite structure using embedded FBG sensors is observed. Practical implications – Observing the advantages of the FBG sensors for strain measurement will promote using FBG sensors for damage detection related to the SHM applications. Originality/value – This paper presents applications of FBG sensors on thin composite beams, which reveal the suitability of FBG sensors for SHM of lightweight composite structures.
关键词： Torsion test,Tension test,Structural health monitoring,Composite beams,Fibre Bragg grating sensors
更新于2025-09-23 15:22:29