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Multi-parameter sensor based on single Long Period Grating in Panda fiber for the simultaneous measurement of SRI, temperature and strain
摘要： In this work, a three-parameter sensor for the simultaneous measurement of surrounding refractive index (SRI), temperature and strain is presented. It is based on a single Long Period Grating (LPG) written in a polarization-maintaining Panda fiber, by means of a simple technique based on Electric Arc Discharge. For the purpose, it is performed the monitoring of the wavelength shift of three different resonances, each one associated to a different cladding mode. Moreover, the set of resonances is acquired for two polarizations of the input light, i.e. aligned to the slow and fast axis of the fiber. The three-parameter sensing is promoted by the fact that the resonance dips show different sensitivities to SRI, temperature and strain, which change their magnitudes and signs when the polarization is switched. It was demonstrated that the sensor can be applied to simultaneously measure SRI in range 1.33–1.40, temperatures comprised in 20–60 °C, and strain of hundreds of με. This device could find application in the fields of materials science and structural health monitoring.
关键词： Refractive index sensor,Temperature sensor,Fiber grating sensor,Strain sensor,Multi-parametric sensor,Long period grating
更新于2025-11-28 14:24:03
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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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Refractive index sensor based on ultrafine tapered single-mode nocladding single-mode fiber structure
摘要： A refractive index (RI) sensor based on a tapered no cladding fiber (NCF) is proposed theoretically and experimentally. The RI sensor is fabricated by splicing a NCF in the middle of two single mode fibers (SMF), and then the NCF is tapered to get lower waist diameter. Due to the lack of cladding, surrounding refractive index (SRI) can directly affect the light propagation of NCF, and the decrease of diameter can further improve the RI sensitivity by strengthening the evanescent field. The sensitivity with different lengths and waist diameters of NCF is investigated. It is observed that there are different linear relationships in different refractive interval and the RI sensitivity increases obviously with the waist diameter decreasing, especially when it is below 30 μm. RI sensitivity of the sensor reaches 686 nm/RIU when the waist diameter is 13 μm and SRI is at the range of 1.333–1.350. The sensor can be widely used in biosensing for its simple operation and high sensitivity at low SRI.
关键词： Refractive index sensor,Multimode interference,No cladding fiber,Tapering
更新于2025-11-28 14:23:57
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Ultrasensitive refractive index sensor based on parallel-connected dual Fabry-Perot interferometers with Vernier effect
摘要： A kind of ultrasensitive refractive index sensor based on parallel-connected dual Fabry-Perot interferometers (FPIs) with Vernier effect is proposed and demonstrated. The open and closed cavity FPIs are used as the sensing and reference units, respectively. The Vernier effect is realized by superimposing the reflective comb spectra of the dual FPIs, which have slightly different free spectral ranges. The open groove of the open cavity FPI provides a convenient, efficient and economical method for filling in or draining out the cavity. The stability, repeatability and temperature response of the structures are investigated. Experimental results indicate that the proposed sensing structure features high sensitivity, good stability, quick and accurate measurement.
关键词： Refractive index sensing,Fabry-Perot interference,Vernier effect,Fiber-optic sensor
更新于2025-11-28 14:23:57
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Simultaneous Measurement of Refractive Index and Temperature Based on a Peanut-Shape Structure In-Line Fiber Mach–Zehnder Interferometer
摘要： We proposed a peanut-shape structure in-line fiber Mach–Zehnder interferometer (MZI) for simultaneous measurement of refractive index (RI) and temperature. Two kinds of demodulation methods were investigated and compared. The wavelength-related and phase-related character matrices of the in-line fiber MZI were determined for simultaneous measurement of RI and temperature, respectively. For the wavelength-related measurement, the highest temperature and RI sensitivities were 0.0709 nm/°C and ?47.3620 nm/RIU, respectively. The phase-related measurement was with a lower measuring errors compared to the wavelength-related measurement, and the highest temperature and RI sensitivities were ?0.0632rad/°C (0.0764 nm/°C) and 77.0995rad/RIU (?93.2429 nm/RIU), respectively. The minimum measuring errors of temperature and RI were 0.3800 °C and 0.0004 RIU, respectively.
关键词： Mach–Zehnder interferometer,simultaneous measurement of refractive index and temperature,Optical fiber sensor,peanut-shape structure
更新于2025-11-28 14:23:57
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Monolithic metal dimer-on-film structure: new plasmonic properties introduced by the underlying metal
摘要： Dimers -two closely-spaced metallic nanostructures- are one of the primary nanoscale geometries in plasmonics, supporting high local field enhancements in their interparticle junction under excitation of their hybridized “bonding” plasmon. However, when a dimer is fabricated on a metallic substrate, its characteristics are changed profoundly. Here we examine the properties of an Au dimer on an Au substrate. This structure supports a bright “bonding” dimer plasmon, screened by the metal, and a lower energy magnetic charge transfer plasmon. Changing the dielectric environment of the dimer-on-film structure reveals a broad family of higher-order hybrid plasmons in the visible region of the spectrum. Both the localized surface plasmons resonances (LSPR) of the individual dimer-on-film structures as well as their collective surface lattice resonances (SLR) show a highly sensitive refractive index sensing response. Implementation of such all-metal magnetic-resonant nanostructures offers a promising route to achieve higher-performance LSPR- and SLR-based plasmonic sensors.
关键词： Plasmonics,localized surface plasmon resonance,surface lattice resonance,LSPR sensing,refractive index sensing
更新于2025-11-21 11:24:58
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The impact of ZnO configuration as an external layer on the sensitivity of a bi-layer coated polymer optical fiber probe
摘要： Salinity magnitude changes are a critical factor for determining the chemistry of natural water bodies and biological processes. Label-free refractive index sensors are promising devices for detecting these changes. A polymer optical fiber (POF) sensor modified with cladding treatment and a bi-layer zinc oxide/silver (ZnO/Ag) nanostructure coating to determine sodium chloride concentration changes through refractive index variations in water is experimentally demonstrated. The use of three ZnO nanostructure shapes, nanoparticles and horizontally and vertically oriented nanorods, as an external layer and a broad spectrum light source from the visible (Vis) to the near infrared (NIR) region are investigated to achieve optimum sensitivity. The rms roughness, optical band-gap and zeta potential (ZP) value for the vertically oriented sample are 148 nm, 3.19 eV and 5.96 mV, respectively. In the NIR region the wavelength–intensity sensitivity values of probes coated with ZnO nanoparticles and horizontally and vertically oriented nanorods are 104 nm RIU?1–12 dB RIU?1, 63 nm RIU?1–10 dB RIU?1 and 146 nm RIU?1–22 dB RIU?1, respectively, and in the Vis area the values are 65 nm RIU?1–14 dB RIU?1, 58 nm RIU?1–11 dB RIU?1 and 89 nm RIU?1–23 dB RIU?1, respectively. The maximum amplitude sensitivity is obtained for the probe coated with vertically aligned ZnO nanorods in the NIR area due to the deeper penetration of evanescent waves, a higher surface-volume ratio, better crystallinity, more adhesive interactions with salt molecules, larger surface roughness and higher-order dispersion compared to the other coated ZnO nanostructures.
关键词： sensitivity,salinity,nanorods,refractive index sensors,ZnO/Ag nanostructure,polymer optical fiber,nanoparticles
更新于2025-11-14 15:25:21
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Measurement of Optical Constants of TiN and TiN/Ti/TiN Multilayer Films for Microwave Kinetic Inductance Photon-Number-Resolving Detectors
摘要： We deposit thin titanium nitride (TiN) and TiN/Ti/TiN multilayer ?lms on sapphire substrates and measure the re?ectance and transmittance in the wavelength range from 400 to 2000 nm using a spectrophotometer. The optical constants (complex refractive indices), including the refractive index n and the extinction coef?cient k, have been derived. With the extracted refractive indices, we propose an optical stack structure using low-loss amorphous Si (a-Si) anti-re?ective coating and a backside aluminum (Al) re?ecting mirror, which can in theory achieve 100% photon absorption at 1550 nm. The proposed optical design shows great promise in enhancing the optical ef?ciency of TiN-based microwave kinetic inductance photon-number-resolving detectors.
关键词： TiN,Optical constants,Microwave kinetic inductance detectors,Refractive index
更新于2025-11-14 15:25:21
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[IEEE 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC) - Waikoloa Village, HI, USA (2018.6.10-2018.6.15)] 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC) - Prediction and validation of solar cell-to-module and environmental losses based on refractive index data for various encapsulation materials
摘要： Updated complex refractive index data (n and (cid:2)(cid:3)(cid:4) are compiled for various commercial and research solar module encapsulants. The data are used as inputs to ray-tracing simulations to predict CTM loss for standard screen print solar modules and compared to calculations of CTM loss from actual IV and EQE measurements made at the cell and module levels. It is found that this method results in adequate predictions, with important encapsulant (cid:5)(cid:6)(cid:7)(cid:8)(cid:7)(cid:5)(cid:9)(cid:10)(cid:8)(cid:11)(cid:12)(cid:9)(cid:11)(cid:5)(cid:4)(cid:13)(cid:14)(cid:8)(cid:4)(cid:15)(cid:11)(cid:16)(cid:11)(cid:15)(cid:11)(cid:17)(cid:11)(cid:16)(cid:18)(cid:4)(cid:19)(cid:20)(cid:21)(cid:4)(cid:5)(cid:22)(cid:8)(cid:8)(cid:10)(cid:16)(cid:9)(cid:4)(cid:23)(cid:14)(cid:12)(cid:12)(cid:24)(cid:4)(cid:4)(cid:20)(cid:6)(cid:10)(cid:4)(cid:16)(cid:4)(cid:7)(cid:16)(cid:25)(cid:4)(cid:2)(cid:4)(cid:7)(cid:8)(cid:10)(cid:4) also used to predict CTM current loss following damp-heat cycling of modules.
关键词： solar module,CTM loss,encapsulant,ray-tracing,refractive index
更新于2025-10-22 19:40:53
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Investigation of an in-line fiber Mach–Zehnder interferometer based on peanut-shape structure for refractive index sensing
摘要： An in-line fiber Mach–Zehnder interferometer (MZI) for refractive index (RI) sensing was proposed, and the interferometer was fabricated by cascading two peanut-shape structures in the single mode fiber using the commercial fusion splicer. A model of the peanut-shape profile was used to calculate the power distribution of the modes in the device. The RI sensing performances of the peanut-shape structure in-line fiber MZIs with two different arm length (30 and 100 mm) were investigated. As the sensor with a short arm length of 30 mm, the RI sensitivity of ?67.355 nm/RIU was achieved for the RI range of 1.33–1.37. As the sensor with a long arm length of 100 mm, the simultaneous RI and temperature measurement was realized to eliminate the temperature and RI cross sensitivity, and the highest RI and temperature sensitivities of ?67.953 nm/RIU and 0.073 nm/?C were obtained, respectively.
关键词： Simultaneous refractive index and temperature measurement,Optical fiber sensor,Refractive index measurement,Mach–Zehnder interferometer,Peanut-shape structure
更新于2025-09-23 15:23:52