- 标题
- 摘要
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- 实验方案
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Highly Sensitive, Affordable, and Adaptable Refractive Index Sensing with Silicon‐Based Dielectric Metasurfaces
摘要： A sensing platform is presented that uses dielectric Huygens source metasurfaces to measure refractive index changes in a microfluidic channel with experimentally measured sensitivity of 323 nm RIU?1, a figure of merit (FOM) of 5.4, and a response of 8.2 (820%) change in transmittance per refractive index unit (T/RIU). Changes in the refractive index of liquids flown through the channel are measured by single-wavelength transmittance measurement, requiring only a simple light source and photodetector, significantly reducing device expense in comparison to state-of-the-art refractive index sensing technologies. A technoeconomic analysis predicts a device costing ≈$2400 that is capable of detecting refractive index changes of the order of 2*10?8. The metasurfaces utilized are low profile, scalable, and use materials and fabrication processes compatible with CMOS and other technologies making them suitable for device integration. The Huygens metasurface system, characterized by spectrally overlapping electric and magnetic dipole modes, offers a high degree of customizability. Interplay between the two resonances may be controlled via metasurface geometry, leading to tunability of device sensitivity and measurement range. Ultrahigh sensitivity of 350 nm RIU?1 with FOM of 219, corresponding to single-wavelength sensitivity of 360 RIU?1, is demonstrated computationally through use of antisymmetric resonances of a Huygens metasurface illuminated at small incidence angles.
关键词： metasurface,refractive index sensing,subwavelength structures,biosensing,nanophotonics
更新于2025-09-04 15:30:14
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DESIGNING PLANE WAVE MODULATORS USING 1DPC NANOSTRUCTURE WITH R-GRIN DEFECT LAYER
摘要： In this paper, we introduce plane wave modulators that are designed using one-dimensional photonic crystals (1DPC) containing radial gradient refractive index (r-GRIN) defect layers. Three kinds of r-GRIN materials with di?erent refractive index distribution functions are applied in numerical analysis. The properties of the phase and intensity of the transmitted plane wave beam through proposed structures are studied using the transfer matrix method. Radially-dependent defect modes, modulated phase and intensity are obtained according to the refractive index distribution functions. The results are predictable by regarding the Bragg condition and destructive interference, which are the origins of the photonic band gap (PBG). Due to the radial-dependency of the defect layer’s refractive index, the rays passing through di?erent transverse positions experience di?erent optical pathways. Therefore, the defect modes and transmitted spectrum (phase and amplitude) vary transversely. This study demonstrates another ability of the arti?cial PC structures to design plane wave modulators and manipulate its phase and intensity.
关键词： radial gradient refractive index,transfer matrix method,one-dimensional photonic crystals,plane wave modulators,photonic band gap
更新于2025-09-04 15:30:14
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2018) - Nagoya (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Experimental Characterization of Artificial Human Skin with Melanomas for Accurate Modelling and Detection in Healthcare Application
摘要： A preliminary investigation is carried out on the artificial human skin tissues with and without metastatic melanomas using Terahertz Time Domain Spectroscopy (THz-TDS). Both the refractive indexes and absorption coefficients of artificial skin with melanomas are higher than the normal artificial skin samples over the entire frequency range between 0.2 THz to 1.6 THz. The reason is that tumour cells degrade the in contraction of fibroblasts causing more water content malignant tissues. This study quantifies the impact of melanomas on the optical parameters of artificial skin tissue and can help in techniques that will diagnose and prevent tumours at the early stage.
关键词： artificial human skin,absorption coefficient,Terahertz Time Domain Spectroscopy,refractive index,melanomas
更新于2025-09-04 15:30:14
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DESIGN OF A PYRAMIDAL HORN ANTENNA WITH LOW E-PLANE SIDELOBES USING TRANSFORMATION OPTICS
摘要： Transformation optics is a convenient way to control the pattern of electromagnetic ?elds. In this paper, using a novel transformation, we propose the design procedure of a horn antenna having low backlobe and sidelobe levels in its E-plane. By applying conformal transformation, the rectangular horn proposed in this paper can be realized with isotropic materials. This proposed antenna can be easily implemented by both ordinary dielectric materials and isotropic graded refractive index (GRIN) materials. In the ?rst proposed design, in addition to the isotropy, homogeneity is furthermore introduced into the horn, and only four kinds of isotropic materials are required throughout. In the second design, it is demonstrated that the designed structure can also be implemented by graded photonic crystals (GPCs) operating in metamaterial regime. They have low loss as well as broad frequency band and are easy to implement. Simulation results are presented to validate the design approach.
关键词： low sidelobes,horn antenna,graded refractive index,graded photonic crystals,Transformation optics,isotropic materials,conformal transformation
更新于2025-09-04 15:30:14
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Real-Time Study of the Disequilibrium Transfer in Vanadium Flow Batteries at Different States of Charge via Refractive Index Detection
摘要： Studying the disequilibrium transfer of the electrolyte in vanadium redox ?ow batteries is essential for the application of the batteries. Due to the lack of proper detection techniques, the real-time study of the disequilibrium transfer is di?cult. In this paper, a real-time refractive index detector with high resolution is developed to study the material transfer in the positive electrolyte at di?erent states of charge. It is found that the rapid imbalance of the electrolyte occurs at the initial state of battery operation, and the disequilibrium transfer rate of materials in the electrolyte accelerates with an increase of the state of charge. During the charge/discharge process, the disequilibrium transfers of vanadium and sulfate show di?erent behaviors. This real-time refractive index detector is bene?cial for studying the electrochemical process of vanadium ?ow batteries and helpful to the optimization of the operational parameter.
关键词： vanadium redox ?ow batteries,electrochemical process,refractive index detection,state of charge,disequilibrium transfer
更新于2025-09-04 15:30:14
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Estimation of refractive index for biological tissue using micro-optical coherence tomography
摘要： The refractive index of biological tissue is required for investigating the tissue’s optical properties. Efforts have been made to characterize refractive indices of biological tissues at a single wavelength, but it is more convenient to know the Cauchy’s coefficients, which provide refractive index over a wide range of wavelengths. We demonstrate a method to noninvasively provide the Cauchy’s dispersion coefficients of biological tissues using micro-optical coherence tomography. Using short-frequency Fourier transforms, the relative optical thickness of the sample in the wavelength range of the broadband source was obtained from interferograms. The coefficients of Cauchy’s equation were estimated based on the wavelength-dependent sample thickness. We validated the proposed method using distilled water and fresh rat cornea ex vivo, and the experimental results were consistent with the reference data.
关键词： Cauchy’s formula,Refractive index,Optical coherence tomography,Cauchy’s dispersion coefficients
更新于2025-09-04 15:30:14