- 标题
- 摘要
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- 实验方案
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Full wave analysis of plane wave diffraction by a finite sinusoidal grating: E-polarization case
摘要： Plane wave diffraction studies of a finite sinusoidal grating have previously assumed that the grating length is large in wavelengths and the depth of its corrugations is small compared to a wavelength. This paper introduces a rigorous technique, the Method of Analytical Regularization (MAR), which removes these restrictions. The solution obtained by this method is free from limitations on the parameters of sinusoidal grating and possesses the capability to achieve predetermined accuracy of computations uniformly in a wide frequency band. The results of previous studies, which employed the Wiener-Hopf technique combined with a perturbation method, are compared with those obtained by the MAR; excellent concordance of results in the common parameter regimes of applicability of both methods is found. The different regimes of applicability of each approach are identified; within these, the MAR provides effective and efficient solutions to benchmark problems for testing other approximate techniques.
关键词： efficient computational algorithm in wide frequency band,scattering of E-polarized plane wave,method of analytical regularization,Floquet modes for finite grating,finite sinusoidal grating,Wiener-Hopf technique combined with perturbation method
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE 7th International Conference on Photonics (ICP) - Kuah (2018.4.9-2018.4.11)] 2018 IEEE 7th International Conference on Photonics (ICP) - Experimental Analyses of Confined Thermal Effect on Chirped Fiber Bragg Grating
摘要： Chirped fiber Bragg gratings (C-FBGs) have found various important applications in the field of optical communication and sensing. These applications manipulated the distinctive refractive index structures, wherein its spectral response is modifiable by variation of its local physical property. This paper specifically analyzes the effect of localized thermal effect on C-FBG using a micro-size heating element to achieve confined heating. The results reveal that localized thermal effect will produce a phase-shift dip in the spectrum, whose depth, linewidth and center wavelength are correlated to the magnitude and position of the applied heat. This knowledge unveils the possibility of elastic spectral shaping of C-FBG, which will allow it to further find new applications.
关键词： fiber Bragg grating,Chirped fiber Bragg grating,confined heating
更新于2025-09-23 15:23:52
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Temperature fiber sensing of Li-ion batteries under different environmental and operating conditions
摘要： In this work, a network of fiber sensors has been developed for real time, in situ, and in operando multipoint monitoring the surface temperature distribution on a smartphone Li-ion battery (LiB). Different temperature and relative humidity conditions are considered, in order to mimic the LiB response in the dry, temperate, and cold climates. In total, the temperature variations that occur in five different locations of the LiB are monitored, during constant current charge and different discharge rates, under normal and abusive operating conditions, performing a thermal spatial mapping of the battery surface. In general, the sensors detect temperature variations according to the voltage signal change and faster variations of voltage usually translate in higher temperature rise at the LiB surface. For instance, under abusive discharge, where the voltage drop is fast, the temperature increases at least twice when compared to the normal operating conditions. Absolute temperature values as high as (65.0 ± 0.1) °C are detected by the optical sensor located near the electrodes, under the higher discharge rate (5.77 C) and dry climate. A thermal gradient is identified from the top to the bottom on the LiB surface during the experimental tests. A lower battery performance is observed when it operates under the cold climate, with maximum temperature variations of (30.0 ± 0.1) °C for the higher discharge rate. These results can be helpful to design of next generation of LiBs, improving a faster cooling in critical areas, in order to reduce accumulated heat and preventing consequences such as thermal runaway and failure.
关键词： Fiber Bragg grating sensors,Temperature monitoring,Abnormal operating conditions,Environment,Safety,Li-ion batteries
更新于2025-09-23 15:23:52
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Low-power-consumption Fiber-optic Anemometer based on Long-period Grating with SWCNT Coating
摘要： We report a low-power-consumption fiber-optic 'hot wire' anemometer (HWA) based on long-period grating (LPG) with single-wall carbon nanotubes (SWCNTs) coating. A uniform SWCNT film is deposited on a bare LPG acting as both light coupling and sensing element. By carefully selecting the order of the cladding mode and operating wavelength, the LPG shows a much higher temperature sensitivity than that of a regular fiber Bragg grating (FBG). Besides, SWCNT is a single-wall cylindrical nanostructure material with excellent absorption in the infrared range and high thermal conductivity. Due to these two features, the proposed sensor has extremely low power consumption and simple operation by utilizing a broadband light source (BBS) as both heating source and probing light source. A sensitivity of 102.5 pm/(m/s) at the wind speed of 1 m/s was obtained experimentally with 1.6-μm-thick SWCNT film.
关键词： Temperature.,Fiber-optic anemometer,long-period fiber grating,Carbon nanotube
更新于2025-09-23 15:23:52
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Inverse design and demonstration of broadband grating couplers
摘要： We present a gradient-based optimization strategy to design broadband grating couplers. Using this method, we are able to reach, and often surpass, a user-specified target bandwidth during optimization. The designs produced for 220 nm silicon-on-insulator are capable of achieving 3 dB bandwidths exceeding 100 nm while maintaining central coupling efficiencies ranging from -3.0 dB to -5.4 dB, depending on partial-etch fraction. We fabricate a subset of these structures and experimentally demonstrate gratings with 3 dB bandwidths exceeding 120 nm. This inverse design approach provides a flexible design paradigm, allowing for the creation of broadband grating couplers without requiring constraints on grating geometry.
关键词： inverse design,optimization,broadband,fiber-packaging,grating couplers
更新于2025-09-23 15:23:52
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Electromagnetically induced holographic imaging with Rydberg atoms
摘要： Electromagnetically induced holographic imaging using strongly interacting Rydberg atoms is investigated via electromagnetically induced grating (EIG). We consider two schemes, i.e., by direct detection of holographic imaging pattern, known as electromagnetically induced classical holographic imaging (EICHI), and by employing entangled photon pairs for imaging which is called as electromagnetically induced quantum holographic imaging (EIQHI). Both the schemes are employed to obtain 1D and 2D holographic imaging. In EICHI and EIQHI, amplitude and phase information of EIG can be imaged with controllable image variation in size. It is noticed that holographic imaging is influenced by van der Waals (vdW) effect present in Rydberg atoms.
关键词： Electromagnetically induced grating,Rydberg atoms,Quantum imaging,Electromagnetically induced holographic imaging,van der Waals effect
更新于2025-09-23 15:23:52
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High-precision FBG demodulation using amplitude ratio curve with sharp peak
摘要： For the fiber Bragg grating (FBG) sensor based on the reflection peak position searching demodulation algorithms, a key problem is that the demodulation precision of measurement signal is seriously limited by the full width half maximum (FWHM) of the FBG reflection spectrum. In this paper, in order to overcome this problem and enhance the measurement precision, we proposed a high-precision demodulation method based on amplitude ratio curve to instead of the FBG reflection spectrum, which can increase the sensing precision significantly. In this method, the Bragg wavelength of FBG is modulated periodically with a sinusoidal function to obtain a series of reflection spectra. Then at each wavelength the amplitude ratio between second harmonic frequency component and fundamental frequency component is calculated to create the amplitude ratio curve. Here, we present a comprehensive theoretical analysis and experimental demonstration to verify the advantages of this method. Comparing with the demodulation method based on the FBG reflection spectrum, the average maximum measure error (MME) of Bragg wavelength is reduced from ± 1.54 pm to ± 0.15 pm, which improved by 10.3 times. In addition, the influence of the modulation amplitude and sampling frequency on demodulation accuracy are also studied in this paper.
关键词： Amplitude ratio curve,High precision temperature measurement,Fiber Bragg grating
更新于2025-09-23 15:23:52
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Deformation sensing and electrical compensation of smart skin antenna structure with optimal fiber Bragg grating strain sensor placements
摘要： Skin antenna structure is a kind of multifunctional composite structure in which printed antennas are integrated. This paper proposes a new smart skin antenna structure with embedded fiber Bragg grating (FBG) strain sensors. Utilizing the measured strains from limited FBG strain sensors, the deformation shapes are reconstructed by using a strain–displacement transformation, and the deteriorated radiation patterns caused by the deformations are compensated by using a strain-electromagnetic coupling mode which is derived and validated for the first time in the paper. Moreover, a two-step sensor placement method considering the information redundancy is proposed to determine optimal FBG strain sensor locations. The comparisons show that the two-step sensor placement method is advantageous in terms of the sensor distribution and computational cost. The fabrication process of the smart skin antenna structure was presented, and an experimental system with optimal sensor placements was developed. The measured results demonstrate that the reconstructed shapes agree well with the real ones, and that the deteriorated radiating patterns were almost completely restored to the desired ones. The proposed smart skin antenna structure which can provide the electromagnetic receiving-sending, structural deformation monitoring and electrical correction functions has a potential application prospect in the future mobile vehicle.
关键词： Fiber Bragg grating,Deformation sensing,Electrical compensation,Smart skin antenna,Optimal sensor placement
更新于2025-09-23 15:23:52
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Optical and Digital Key Enabling Techniques for SDM-Based Optical Networks
摘要： In order to support, in a cost-effective way, the data capacity demand in the context of future 5G networks, a new set of advanced technologies need to be explored, as it is the case of space-division multiplexing (SDM) along with energy efficient coherent detection based modulation formats. This paper presents the recent results on enabled optical networks based on SDM for high capacity optical networks compatible with 5G network infrastructure and data center connectivity. In particular, we demonstrate the viability of using Long-Period Gratings (LPGs) in multi-core fibers (MCFs) to develop different components for multicore-based SDM systems, such as pump couplers and core/wavelength selective multi-core switches and couplers. Moreover, we also present and characterize the performance of different digital signal processing (DSP) algorithms and subsystems supporting optical coherent detection in SDM systems.
关键词： Coherent detection,long period grating,generalized Stokes space,digital signal processing,space-division multiplexing,space-division demultiplexing
更新于2025-09-23 15:23:52
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Grating coupler with reduced back reflection using λ/4 offset at its grating sub-teeth
摘要： We demonstrate a grating coupler with reduced back reflection on silicon-on-insulator (SOI) platform. Each grating tooth of the grating coupler is uniformly divided into multiple sub-teeth with λ/4 offset between two adjacent sub-teeth, reducing the Fresnel reflection from interfaces between core and cladding materials in transmission direction. The back reflection can be theoretically suppressed from ?12 dB to below ?30 dB for a focusing grating coupler working at TM polarization. Experimental results show that the effect of Fresnel reflection on transmission spectrum of the proposed grating coupler is significantly reduced compared to conventional grating coupler. Furthermore, a microring resonator using the proposed focusing grating coupler to couple light into and out of waveguide is fabricated. The measured spectra show that fluctuations on transmission spectra of the ring resonator are effectively suppressed, especially for the drop-port, a well-shaped resonance peak is clearly observed, making the resonance wavelength easily distinguishable, which is highly required in sensing applications using wavelength interrogation.
关键词： Fresnel reflection,grating coupler,waveguide,ring resonator
更新于2025-09-23 15:23:52