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[IEEE 2018 IEEE Sensors - New Delhi (2018.10.28-2018.10.31)] 2018 IEEE SENSORS - Highly Sensitive Refractometer Using a Fiber Bragg Grating Fabricated by Femtosecond Laser
摘要： A highly localized fiber Bragg grating is inscribed using point-by-point femtosecond laser direct writing technique. By monitoring the location of the cut off wavelength, we demonstrate that the FBG has a highly-linear sensitivity for refractive index (RI) measurement. By monitoring the “peak-to- dip” intensity change near the cut-off wavelength, an ultra-high refractive index sensitivity of 2924.3dB/RIU and a RI resolution of 3.4×10-7 are achieved. As different surrounding refractive index corresponds to different location of the cut off wavelength, this FBG based refractometer can measure RI with wide range measurement range together with high sensitivity.
关键词： Femtosecond laser,Fiber Bragg grating,Refractive index sensors
更新于2025-11-28 14:23:57
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Widely Wavelength-tunable Mode-locked Fiber Laser Based on a 45° Tilted Fiber Grating and Polarization Maintaining Fiber
摘要： We present a passively mode-locked Erbium-doped fiber laser with tunable parameters including central wavelength, 3dB bandwidth and pulse duration. The mode-locking mechanism of the laser is realized by using single-walled carbon nanotubes polyvinyl alcohol (SWCNTs-PVA) composite film as saturable absorber. The tunable operation is implemented via a fiber birefringence filter consisting of a polarization maintaining (PM) fiber and a Brewster fiber grating. The laser achieves a maximum spectral tuning range of 36 nm with 8 cm PM fiber. The maximum spectral width variation of 5.19 nm is acquired when the PM fiber is 12 cm. Simultaneously, the spectral widths of pulses at different central wavelengths are also adjustable. Furthermore, the total cavity length is 8.28 m, which is the shortest cavity length to obtain such wide tuning range in an Erbium-doped fiber laser based on SWCNTs.
关键词： Passively mode-locked fiber laser,spectral width,wavelength-tunable,pulse width,tilted fiber grating
更新于2025-11-28 14:23:57
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Ultrasensitive tantalum oxide nano-coated long-period gratings for detection of various biological targets
摘要： In this work we discussed a label-free biosensing application of long-period gratings (LPGs) optimized in refractive index (RI) sensitivity by deposition of thin tantalum oxide (TaOx) overlays. Comparing to other thin film and materials already applied for maximizing the RI sensitivity, TaOx offers good chemical and mechanical stability during its surface functionalization and other biosensing experiments. It was shown theoretically and experimentally that when RI of the overlay is as high as 2 in IR spectral range, for obtaining LPGs ultrasensitive to RI, the overlay’s thickness must be determined with subnanometer precision. In this experiment the TaOx overlays were deposited using Atomic Layer Deposition method that allowed for achieving overlays with exceptionally well-defined thickness and optical properties. The TaOx nano-coated LPGs show RI sensitivity determined for a single resonance exceeding 11,500 nm/RIU in RI range nD=1.335-1.345 RIU, as expected for label-free biosensing applications. Capability for detection of various in size biological targets, i.e., proteins (avidin) and bacteria (Escherichia coli), with TaOx-coated LPGs was verified using biotin and bacteriophage adhesin as recognition elements, respectively. It has been shown that functionalization process, as well as type of recognition elements and target analyte must be taken into consideration when the LPG sensitivity is optimized. In this work optimized approach made possible detection of small in size biological targets such as proteins with sensitivity reaching 10.21 nm/log(ng/ml).
关键词： protein detection,label-free biosensing,optical fiber sensor,tantalum oxide,bacteria detection,long-period grating,atomic layer deposition
更新于2025-11-28 14:23:57
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Refractive Index Measurement of Lithium Ion Battery Electrolyte with Etched Surface Cladding Waveguide Bragg Gratings and Cell Electrode State Monitoring by Optical Strain Sensors
摘要： In this scientific publication, a new sensor approach for status monitoring, such as state of charge and state of health, of lithium ion batteries by using special Bragg gratings inscribed into standard optical glass fibers is presented. In addition to well-known core gratings, embedded into the anode of 5 Ah lithium ion pouch cells as a strain monitoring unit, the manufacturing of a surface cladding waveguide Bragg grating sensor incorporated into the cell’s separator, that is sensitive to changes of the refractive index of the surrounding medium, is demonstrated. On the basis of the experiments carried out, characteristics of the cell behavior during standard cyclization and recognizable marks in subsequent post-mortem analyses of the cell components are shown. No negative influence on the cell performance due to the integrated sensors have been observed; however, the results show a clear correlation between fading cell capacity and changes of the interior optical signals. Additionally, with the novel photonic sensor, variations in the electrolyte characteristics are determinable as the refractive index of the solution changes at different molar compositions. Furthermore, with the manufactured battery cells, abuse tests by overcharging were conducted, and it was thereby demonstrated how internal battery sensors can derive additional information beyond conventional battery management systems to feasibly prevent catastrophic cell failures. The result of the research work is an early stage photonic sensor that combines chemical, mechanical and thermal information from inside the cell for an enhanced battery status analysis.
关键词： lithium ion,battery aging,cladding waveguide,battery electrolyte,optical sensors,battery safety,fiber Bragg grating,electrode active material,status monitoring
更新于2025-11-28 14:23:57
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Young’s Modulus Measurement of Metal Wires Using FBG Sensor
摘要： A novel Young’s modulus measurement scheme based on fiber Bragg gratings (FBG) is proposed and demonstrated experimentally. In our method, a universal formula relating the Bragg wavelength shift to Young’s modulus is derived and metal wires are loaded strain by using the static stretching method. The Young’s modulus of copper wires, aluminum wires, nickel wires, and tungsten wires are separately measured. Experimental results show that the FBG sensor exhibits high measurement accuracy, and the measurement errors relative to the nominal value is less than 1.0%. The feasibility of the FBG test method is confirmed by comparing it with the traditional charge coupled device (CCD) imaging method. The proposed method could find the potential application in the material selection, especially in the field that the size of metal wires is very small and the strain gauges cannot be qualified.
关键词： Young’s modulus,static stretching method,metal wire,Fiber Bragg grating
更新于2025-11-28 14:23:57
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An Optical MEMS Acoustic Sensor Based on Grating Interferometer
摘要： Acoustic detection is of great signi?cance because of its wide applications. This paper reports a Micro-Electro-Mechanical System (MEMS) acoustic sensor based on grating interferometer. In the MEMS structure, a diaphragm and a micro-grating made up the interference cavity. A short-cavity structure was designed and fabricated to reduce the impact of temperature on the cavity length in order to improve its stability against environment temperature variations. Besides this, through holes were designed in the substrate of the grating to reduce the air damping of the short-cavity structure. A silicon diaphragm with a 16.919 μm deep cavity and 2.4 μm period grating were fabricated by an improved MEMS process. The fabricated sensor chip was packaged on a conditioning circuit with a laser diode and a photodetector for acoustic detection. The output voltage signal in response to an acoustic wave is of high quality. The sensitivity of the acoustic sensor is up to ?15.14 dB re 1 V/Pa @ 1 kHz. The output signal of the high-stability acoustic sensor almost unchanged as the environment temperature ranged from 5 ?C to 55 ?C.
关键词： interferometry,stability,acoustic sensors,MEMS,grating
更新于2025-11-28 14:23:57
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Pressure measurement in combusting and non-combusting gases using laser-induced grating spectroscopy
摘要： The measurement of pressure using laser-induced thermal grating spectroscopy, LITGS, with improved accuracy and precision is reported. Pressure values are derived from the record of the time-profile of LITGS signals by fitting of modelled signals to experimental data. The procedure is described for accurate modelling of the LIGS signals involving a sequence of calculation steps with appropriate weighting and calibration to determine the best-fit value of pressure-dependent parameters for averaged and single-shot measurements. Results are reported showing application of this model-fitting method to measurements of pressure in static cells using LITGS generated from NO in mixtures containing N2 at pressures in the range 0.5–5.0 bar with accuracy of 1–3% and single-shot precision of 4–7%. Time-resolved measurements of pressure, using LITGS signals generated in toluene-seeded fuel vapour, during the compression and expansion strokes of a motored optically accessible engine are reported with pressure-dependent accuracy ranging from better than 10 to around 20% over the cycle and single-shot precision in the range 5–15% over the same range. Measurements in the engine under firing conditions were obtained over a limited range and slightly increased uncertainties associated with varying composition resulting from exhaust gas residuals. The method was found to be of limited utility for measurements in high temperature flames at around ambient pressures.
关键词： Combustion,Laser-induced thermal grating spectroscopy,Non-combusting gases,Pressure measurement,LITGS
更新于2025-11-25 10:30:42
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Hydrogen peroxide detection with a silver nanoparticle grating chip fabricated by plasmonic plating
摘要： An optical detection of hydrogen peroxide (H2O2) is proposed, using grating structures of silver nanoparticles (AgNPs). Periodic line structures of AgNPs are deposited on a gold nanoparticle (AuNP)-decorated glass plate using an interference exposure with a green laser beam, based on the plasmonic plating method. This AgNP grating chip diffracts incident light, and the diffraction efficiency is dependent on the amount of AgNPs. By applying a drop of H2O2 solution onto the chip, the diffraction intensity declines due to the autocatalytic decomposition of AgNPs. A portable measurement system of the diffraction intensity change is constructed, and the H2O2 detection in the concentration range 6.7 – 668 μmol/L is performed in 2 min simply by dropping the H2O2 solution onto the substrate.
关键词： silver nanoparticles,plasmonic plating,optical sensor,hydrogen peroxide detection,diffraction grating
更新于2025-11-25 10:30:42
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Triple-Junction Optoelectronic Sensor with Nanophotonic Layer Integration for Single Molecule Level Decoding
摘要： Interest in developing a rapid and robust DNA sequencing platform has surged over the past decade. Various next-/third-generation sequencing mechanisms have been employed to replace the traditional Sanger sequencing method. In sequencing by synthesis (SBS), a signal is monitored by a scanning charge-coupled device (CCD) to identify thousands to millions of incorporated dNTPs with distinctive fluorophores on a chip. Because one reaction site usually occupies dozens of pixels on a CCD detector, a bottleneck related to the bandwidth of CCD imaging limits the throughputs of the sequencing performance and causes tradeoffs among speed, accuracy, read length, and the numbers of reaction sites in parallel. Thus, current research aims to align one reaction site to a few pixels by directly stacking nanophotonic layers (NPLs) onto a CMOS detector to minimize the size of the sequencing platforms and accelerate the processing procedures. This article reports a custom integrated optoelectronic device based on a triple-junction photodiode (TPD) CMOS sensor in conjunction with NPL integration for real-time illumination and detection of fluorescent molecules.
关键词： planar waveguide,nanophotonic layer,CMOS,triple-junction photodiode (TPD),filter,grating
更新于2025-11-25 10:30:42
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Coordination between Surface Lattice Resonances of Poly(glycidyl Methacrylate) Line Array and Surface Plasmon Resonances of CdS Quantum on Silicon Surface
摘要： In this work, a unique hybrid system is proposed for one-dimensional gratings comprising of poly(glycidyl methacrylate) (PGMA) brushes and CdS quantum dots (CQDs). Generally, the emission of QDs is too weak to be observed in a dry state. Plasmonic resonances of the grating structures can be used to enhance the light emission or absorption of CQDs. The interaction between PGMA plasmonic nanostructures and inorganic CQDs plays a crucial role in engineering the light harvest, notably for optoelectronic applications. Extinction measurements of the hybrid system consisting of a PGMA grating and CQDs are reported. We designed one-dimensional gratings with various resolutions to tune the absorptance peaks of grating. PGMA grating grafted from a 1.5 μm resolution of trench arrays of photoresist exhibited absorptance peak at 395 nm, close to the absorption peak of CQDs, resulting in the photoluminescence enhancement of CQDs on the grating due to high charge carriers’ recombination rate. Generally, the emission of quantum dots occurs under irradiation at characteristic wavelengths. Immobilizing QDs on the grating facilitates the emission of QDs under irradiation of full-wavelength light. Furthermore, the PGMA gratings with CQDs were immersed in various solvents to change the geometries resulting the shift of absorptance peak of grating. The proposed method could be applied for sensing the nature of the surrounding media and vice versa, as well as for various media of solvents.
关键词： one-dimensional grating,CdS quantum dots,PGMA brush
更新于2025-11-14 17:03:37