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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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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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High-resolution refractometry using phase shifting interferometry based on spatial light modulator and vortex probe
摘要： We present a spatial light modulator (SLM) based phase shifting interferometry (PSI) using an optical vortex for sensing the refractive index (RI) of liquids. The vortex phase rotates according to the phase shift introduced by a medium, and its rotation angle quantifies the index of refraction of the sample. An interferometer modified with the SLM is designed to obtain reliable results. We experimentally demonstrate the stability of the SLM-based system by measuring interference and phase fluctuation. Experimental results show that the proposed system keeps the fluctuation small. The vortex probe PSI combined with the SLM-based interferometer enables not only detecting extremely small changes in concentration but also precisely measuring the RI with high resolution of ～10?? refractive index unit.
关键词： Refractive index sensing,Spatial light modulator,Optical vortex,Interferometry
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 15th International Conference on Group IV Photonics (GFP) - Cancun (2018.8.29-2018.8.31)] 2018 IEEE 15th International Conference on Group IV Photonics (GFP) - Phase-Shifted Multimode Bragg Gratings in Silicon-on-Insulator for Sensing Applications
摘要： In this paper, we experimentally characterize the sensitivity of different types of multimode Bragg gratings in Silicon-On-Insulator and demonstrate a high sensitivity of 120 nm per refractive index unit using Bragg gratings for TM polarized light.
关键词： Bragg gratings,refractive index sensing,multimode
更新于2025-09-23 15:22:29
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INVESTIGATION ON PLASMON INDUCED TRANSPARENCY AND ITS APPLICATION IN AN MIM TYPECOMPOUND PLASMONIC WAVEGUIDE
摘要： In this paper, the investigation about a metal-insulator-metal (MIM) compound plasmonic waveguide is reported, which possesses the transmission property of plasmon induced transparency (PIT) and exhibits the potential application of refractive index sensing. The waveguide structure consists of an MIM-type bus waveguide, a horizontally placed asymmetric H-type resonator (AHR), and a circular ring resonator (CRR). The AHR is directly coupled with the bus waveguide, while the CRR is directly coupled to the AHR, but is indirectly coupled to the bus waveguide. Due to the destructive interference between two di?erent transmission paths, PIT e?ect can be observed in the transmission spectrum. The ?nite element method (FEM) is used to study the PIT e?ect in detail. The results show that the transmission characteristics can be ?exibly adjusted by changing the geometric parameters of the structure, and the proposed waveguide structure has potential application prospects in the area of temperature and refractive index sensing with higher sensitivity, better ?gure of merit, and in the area of slow light photonic devices.
关键词： plasmon induced transparency,slow light,MIM waveguide,refractive index sensing
更新于2025-09-23 15:19:57
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Gold-Film-Thickness Dependent SPR Refractive Index and Temperature Sensing with Hetero-Core Optical Fiber Structure
摘要： A simple hetero-core optical ?ber (MMF-NCF-MMF) surface plasmon resonance (SPR) sensing structure was proposed. The SPR spectral sensitivity, full width of half peak (FWHM), valley depth (VD), and ?gure of merit (FOM) were de?ned to evaluate the sensing performance comprehensively. The e?ect of gold ?lm thickness on the refractive index and temperature sensing performance was studied experimentally. The optimum gold ?lm thickness was found. The maximum sensitivities for refractive index and temperature measurement were obtained to be 2933.25 nm/RIU and ?0.91973 nm/? C, respectively. The experimental results are helpful to design the SPR structure with improved sensing performance. The proposed SPR sensing structure has the advantages of simple structure, easy implementation, and good robustness, which implies a broad application prospect.
关键词： hetero-core ?ber structure,optical ?ber sensor,surface plasmon resonance,refractive index sensing,temperature sensing
更新于2025-09-19 17:13:59
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An Ag-assisted silicon slot waveguide sensor model for mid-infrared spectra gas detection with micro-ring air pressure compensation
摘要： In this paper, we introduced a metal assisted silicon slot waveguide for highly sensitive gas detection. Considering the shortage of refractive index sensing and the influence of air pressure, we choose infrared absorption as the concentration sensing mechanism instead of traditional refractive index sensing on silicon device. Because of the thin metal layer under slot waveguide, the sensitivity of sensor is significantly enhanced. Meanwhile, an air pressure detection based on refractive index sensing is realized for signal compensation, which improves the accuracy of sensor when compared with single mechanism sensor. The simulation results of designed waveguide and sensing application have shown the feasibility and improvement of this new gas sensor.
关键词： on-chip sensor,slot waveguides,refractive index sensing,infrared gas absorption
更新于2025-09-19 17:13:59
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Toroidal metasurfaces integrated with microfluidic for terahertz refractive index sensing
摘要： A terahertz refractive index sensor consisting of toroidal dipole resonance metasurface integrated with microfluidic channel is proposed. The excitation of toroidal dipole resonance in this metasurface and the localized electromagnetic field enhancement in microfluidic channel are investigated comprehensively. Numerical results show that the calculated quality factor and the corresponding figure of merit can reach 1103 and 244, much higher than previously reported terahertz metamaterials sensors. Moreover, the refractive index sensing capabilities of non-polar and polar liquids are also investigated, which demonstrate the resonant frequency shift does not depend on the losses of analytes and show this device can be used for sensing various materials, including highly absorptive materials. This proposed structure can be extended to work in other frequency regions and has potential applications in high performance gases, liquids and biological materials sensing.
关键词： toroidal dipole,metasurfaces,microfluidic,refractive index sensing,terahertz
更新于2025-09-19 17:13:59
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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) - Fabrication of surface corrugated Long Period Gratings on Plastic Optical Fibers for Refractive Index Sensing
摘要： We use a simple way to fabricate surface corrugated long period gratings (LPGs) on commercial plastic optical fibers (POFs) by die press print method. The so-obtained LPGs are proposed as refractive index (RI) sensors in this work. The LPGs imprinted on the POFs with different diameters are evaluated, and it shows that an LPG imprinted on a thin POF (with a diameter of 0.25mm) exhibits better RI sensing performance than that of the ones on thick POFs (with diameters of 0.5 and 1.0mm). When the LPG with period of 100μm, groove depth of 45μm was imprinted on the POF with a diameter of 0.25mm, the RI sensitivity of 1998%/RIU with a resolution of 2.70×10-4 RIU is obtained. The sensor is a low-cost solution for RI sensing purpose and with the features of simple structure, easy fabrication and intensity modulation at visible wavelengths.
关键词： Refractive index sensing,Long period grating,Plastic optical fiber
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) - Sensitivity-enhanced refractive index sensor based on series structure of two microfiber knot resonators with Vernier effect
摘要： This paper proposes and experimentally demonstrates a sensor for sensitivity-enhanced refractive index (RI) sensing based on Vernier effect. The Vernier effect achieved by connecting two microfiber knot resonators (MKRs) in series. The sensing principles and spectrum of the structure are studied theoretically and then verified experimentally. The results exhibit that the RI sensor has high sensitivity up to 3301.76 nm/RIU and it is detection resolution is 6.057×10?6 RIU. That is because the microfiber has high proportional evanescent field and Vernier effect multiplies the spectrum of individual MKR. The proposed series structure of two MKRs with high sensitivity, easy fabrication and low cost can be extensively applied to physical, chemical and biological signal detection.
关键词： series structure,microfiber knot resonators,Vernier effect,sensitivity-enhanced,refractive index sensing,easy fabrication
更新于2025-09-16 10:30:52