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The finite-element method (FEM) and eigenmode expansion method (EEM) were adopted to analyze the guided modes and spectrum of phase-shift fiber Bragg grating at five phase-shift degrees (including zero, 1∕4π, 1∕2π, 3∕4π, and π). In previous studies on optical fiber grating, conventional coupled-mode theory was crucial. This theory contains abstruse knowledge about physics and complex computational processes, and thus is challenging for users. Therefore, a numerical simulation method was coupled with a simple and rigorous design procedure to help beginners and users to overcome difficulty in entering the field; in addition, graphical simulation results were presented. To reduce the difference between the simulated context and the actual context, a perfectly matched layer and perfectly reflecting boundary were added to the FEM and the EEM. When the FEM was used for grid cutting, the object meshing method and the boundary meshing method proposed in this study were used to effectively enhance computational accuracy and substantially reduce the time required for simulation. In summary, users can use the simulation results in this study to easily and rapidly design an optical fiber communication system and optical sensors with spectral characteristics. [ABSTRACT FROM AUTHOR]

In this study, a numerical simulation method was employed to investigate and analyze superstructure fiber Bragg gratings (SFBGs) with five duty cycles (50%, 33.33%, 14.28%, 12.5%, and 10%). This study focuses on demonstrating the relevance between design period and spectral characteristics of SFBGs (in the form of graphics) for SFBGs of all duty cycles. Compared with complicated and hard-to-learn conventional coupled-mode theory, the result of the present study may assist beginner and expert designers in understanding the basic application aspects, optical characteristics, and design techniques of SFBGs, thereby indirectly lowering the physical concepts and mathematical skills required for entering the design field. To effectively improve the accuracy of overall computational performance and numerical calculations and to shorten the gap between simulation results and actual production, this study integrated a perfectly matched layer (PML), perfectly reflecting boundary (PRB), object meshing method (OMM), and boundary meshing method (BMM) into the finite element method (FEM) and eigenmode expansion method (EEM). The integrated method enables designers to easily and flexibly design optical fiber communication systems that conform to the specific spectral characteristic by using the simulation data in this paper, which includes bandwidth, number of channels, and band gap size. [ABSTRACT FROM AUTHOR]

This paper proposes a novel design for a highly sensitive high-resolution localized surface plasmon resonance (LSPR) biochemical sensor. The geometrical structure of the sensor consists of three segments. The first segment comprises single-mode fibers located in the output and input ends of the sensor. The second and third segments comprise rectangular nanometal arrays and serve as the analyte regions of the sensor; the amount of displacement between these two segments is one rectangular nonmetal particle. We integrated two breakthrough methods, the object meshing method and the boundary meshing method, with the finite element method to effectively improve the accuracy of simulation outcomes and reduce the amount of time and memory required for performing calculations. Subsequently, we constructed the proposed LSPR biochemical sensor, and the results indicated that the proposed sensor exhibited excellent geometric structure and spectral characteristics. Specifically, the sensor is short (approximately 250 μm) and features high resolution (approximately −130 dB) and high sensitivity (approximately 126,849.1333 nm/RIU). [ABSTRACT FROM AUTHOR]

To enhance further the performance of the current localized surface plasmon resonance (LSPR) biochemical fiber sensor, a novel design model for a short length, high resolution, and high sensitivity was developed in this study. Based on a cross-sectional view of the component, the proposed new LSPR biochemical fiber sensor comprises a single-mode fiber and two types of nano-metal gears. The difference between these two types of nano-metal gears is the angular displacement of a single pitch. In a cylindrical coordinate system, if the φ axis is considered a straight, the LSPR fiber sensor exhibits a clear tessellation array. The numerical simulation method that combines the finite element method (FEM) and eigenmode expansion method (EEM) was used to design and analyze the sensor. In addition, to increase the accuracy of the numerical simulation results, the proposed numerical simulation method included a perfectly matched layer (PML) and a perfectly reflecting boundary condition (PRB). After the design procedures had been performed, the LSPR biochemical fiber sensor designed in this study possesses the advantageous attributes of a short length (74.34779 μm), high resolution (−110 dB), and high sensitivity (93 987 nm/RIU). As far as I know, up to present it possesses the best resolution and sensitivity compared with the other LSPR sensors. [ABSTRACT FROM AUTHOR]

To reduce the error between actual operations and numerical simulations, thereby enabling effective design parameters to be obtained during the sensor production process and increasing the precision of simulated results, we integrated theories relevant to the perfectly matched layer and perfectly reflecting boundary condition with the finite element method and eigenmode expansion method. In addition, the modified simulation method was used to design and research a high-performance nanometal ring-array localized surface plasmon resonance (LSPR) sensor, comprising single-mode fibers (SMFs) and nanometal ring arrays. The existence of LSPR waves is the primary reason that determines whether LSPR sensors exhibit high sensitivity; thus, we examined the ability of the sensor structure to trigger LSPR waves by using the electric field Er of the core mode HE11 on the optical fiber. After employing the relevant algorithms, the resulting images demonstrated the excitation of the LSPR. This nanometal ring-array LSPR fiber sensor is advantageous because of its short length (393.59788 µm), high resolution (approximately -90 dB), and high sensitivity (approximately 38,600 nm/RIU). [ABSTRACT FROM AUTHOR]

Abstract: Utilizing the outstanding-sensitivity characteristic of localized surface plasmon resonance (LSPR), this study developed a new high-performance sensor design model. Based on a cross-sectional view of the component, the proposed new LSPR fiber sensor comprises a single-mode fiber (SMF), nano-metal rings, and nano-metal gears. The numerical simulation method that combines the finite element method (FEM) and eigenmode expansion method (EEM) was used to design and analyze the sensor. In addition, to increase the accuracy of the numerical simulation results, the proposed numerical simulation method included a perfectly matched layer (PML) and a perfectly reflecting boundary condition (PRB). In other words, the FEM and EEM numerical methods involve not only discrete guided modes and discrete LSPR modes in the simulation and design process, but also discrete radiation modes, that is, continuous radiation modes converted using PML and PRB. This study found that the current metallic patterns in the fiber sensor can trigger the LSPR by the electric field E r of the core mode HE11, which is the main reason the novel fiber sensor yields a high performance. After algorithms were performed, images showed evident excitation of the LSPR. The LSPR fiber sensor designed in this study possesses the advantageous attributes of a short length (77.01764μm), high resolution (approximately −80dB), and high sensitivity (approximately 45,062nm/RIU). [Copyright &y& Elsevier]

To enhance sensor sensitivity and resolution, the present study proposes a biochemical sensor utilizing localized surface plasmon resonance to detect minute changes in the refractive index of the analyte. This sensor comprises a single-mode fiber located on the front and back ends of the sensor, which is responsible for the input and output of fiber optic signals, and two geometrical objects arranged in an interwoven pattern in the sensing region at the center of the sensor. In particular, the rectangular metal nanoparticles are arranged in a rectangular fashion and plated in the etched cladding layer to increase the number of nanosized metal particles on the X–Y plane. In addition, to decrease the calculation time and memory capacity while increasing the precision of simulations, a numerical calculation approach with power functions was employed. This approach comprises the finite element method, eigenmode expansion method, perfectly matched layer, perfectly reflecting boundary condition, boundary meshing method, and object meshing method. Triangular meshes were employed as the basis and sensors were divided into object boundaries, small-sized objects, medium-sized objects, and large-sized objects. The meshing ratio was set to 1:9:181:1810. Numerical simulation results indicate that the proposed localized surface plasmon resonance sensor achieved superior length (approx. 170 μm), resolution (approx. −155 dB), and sensitivity (approx. 137,664.4 nm/RIU). [ABSTRACT FROM AUTHOR]

To enhance sensor sensitivity and resolution, the present study proposes a biochemical sensor utilizing localized surface plasmon resonance to detect minute changes in the refractive index of the analyte. This sensor comprises a single-mode fiber located on the front and back ends of the sensor, which is responsible for the input and output of fiber optic signals, and two geometrical objects arranged in an interwoven pattern in the sensing region at the center of the sensor. In particular, the rectangular metal nanoparticles are arranged in a rectangular fashion and plated in the etched cladding layer to increase the number of nanosized metal particles on the X–Y plane. In addition, to decrease the calculation time and memory capacity while increasing the precision of simulations, a numerical calculation approach with power functions was employed. This approach comprises the finite element method, eigenmode expansion method, perfectly matched layer, perfectly reflecting boundary condition, boundary meshing method, and object meshing method. Triangular meshes were employed as the basis and sensors were divided into object boundaries, small-sized objects, medium-sized objects, and large-sized objects. The meshing ratio was set to 1:9:181:1810. Numerical simulation results indicate that the proposed localized surface plasmon resonance sensor achieved superior length (approx. 170 μm), resolution (approx. −155 dB), and sensitivity (approx. 137,664.4 nm/RIU). [ABSTRACT FROM AUTHOR]