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AIP Conference Proceedings [AIP Publishing PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON MATHEMATICAL SCIENCES AND TECHNOLOGY 2018 (MATHTECH2018): Innovative Technologies for Mathematics & Mathematics for Technological Innovation - Penang, Malaysia (10–12 December 2018)] PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON MATHEMATICAL SCIENCES AND TECHNOLOGY 2018 (MATHTECH2018): Innovative Technologies for Mathematics & Mathematics for Technological Innovation - Numerical study of the evanescent field coupling effect on two optical fiber sensors
摘要： In this paper, multi-sensor is proposed based on the evanescent field coupling effect on two optical fibers. The waveguide aligned side by side were numerically simulated using the beam propagation method (OptiBPM) simulator. Optical rays are confined within a waveguide by total internal reflection and closely visualized at the waveguide’s cladding interface via electromagnetic wave theory model. Distinct distances between optical fibers are considered for optical power loss and the sensor operation is explained in terms of these effects. The coupling coefficient express the products between the evanescent part of the field and the propagative part guided in the core. The performance of the device is found satisfactory to build higher order multi-sensor.
关键词： optical fiber sensors,beam propagation method,coupling effect,evanescent field
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) - On-demand design of nanophotonic gratings using artificial neural network
摘要： The design of nanophotonic structures relies on solving the Maxwell’s equation and sweeping parameters in order to obtain the desired properties. The inverse problem, the retrieval of the appropriate parameters from the required electromagnetic responses, remains challenging and time consuming. Here we report on-demand design of photonic gratings using a recurrent neural network. By using back propagation neural network model, we show that a nanophotonic grating can be designed and optimized with predesignated responses. We expect this work will advance the applications of deep learning algorithms in the design of nanophotonic devices.
关键词： nanophotonic structures,nanophotonic grating,back propagation neural network
更新于2025-09-16 10:30:52
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Generating autofocused aberration laser beams with different spectral performance
摘要： We present a flexible approach for generating autofocused aberration laser beams (ALBs) of different wavelengths based on the diffractive optical element (DOE) design with distinct phase transmittance that has radial power q and periodic angular dependence sin(mφ). The diffraction pattern of ALBs strongly depends on the periodic angular power controlled phase of the DOE. During free-space propagation, the ALBs with different wavelengths convert into different light distributions that have mth-order symmetry (for odd m) and 2mth-order symmetry (for even m). The ALBs exhibit autofocusing properties that significantly differ at longer wavelengths relatively with smaller wavelengths. The formation of light intensity distributions in free-space propagation has a sharp focusing feature that strongly depends on the radial power q. The numerically simulated results are presented for wavelengths in the infrared, visible, and ultra-violet regimes. The experimental findings measured at a wavelength of λ = 1064 nm, show good agreement with the numerically simulated results and thus verifying our approach.
关键词： propagation,laser beam shaping,diffractive optics
更新于2025-09-16 10:30:52
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A Novel Plant Propagation-Based Cascaded Fractional Order PI Controller for Optimal Operation of Grid-Connected Single-Stage Three-Phase Solar Photovoltaic System
摘要： Grid-connected photovoltaic (PV) inverters are gaining attention all over the world. The optimal controller setting is key to the successful operation of a grid-connected PV system. In this paper, a novel plant propagation algorithm-based fractional order proportional-integrator (FOPI) controller for cascaded DC link voltage and inner current control of a grid-connected PV controller has been proposed, which outperforms particle swarm optimization-based PI and elephant herding optimization-based FOPI in terms of multicriteria-based analysis. The performance of the proposed controller also has been measured in terms of total harmonic distortion to maintain the appropriate power quality. Also, the proposed controllers were tested under various solar irradiance and voltage sag conditions to show the effectiveness and robustness of the controllers. The whole system is developed in OPAL-RT using MATLAB/Simulink and RT-LAB as a machine-in-loop (MIL) system to validate the performance in real time.
关键词： DC link voltage controller,inner current controller,elephant herding optimization,plant propagation algorithm,grid-connected PV,particle swarm optimization,fractional order PI controller
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE High Power Diode Lasers and Systems Conference (HPD) - Coventry, United Kingdom (2019.10.9-2019.10.10)] 2019 IEEE High Power Diode Lasers and Systems Conference (HPD) - Simulation of the slow-axis beam properties of broad-area lasers and its use in the development of high-brightness sources
摘要： The objective of this work is to demonstrate that the slow-axis beam properties of broad-area diode lasers can be predicted by numerical modeling and that the results guide design decisions in the semiconductor laser development. We present a numerical study for 6 different semiconductor laser single emitter designs and compare the computed results to experimental values. The devices differ in width of the contact opening, cavity length, position and depth of an index trench, and facet re?ectivity.
关键词： Semiconductor Lasers,Index-Guided,Beam Propagation Method,Lasers,Modeling,Gain-Guided,Frequency Domain,Simulation,Thermal Lens,Diode Lasers,Broad-Area
更新于2025-09-16 10:30:52
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Tuning SPP propagation length of hybrid plasmonic waveguide by manipulating evanescent field
摘要： Exploring hybrid plasmonic waveguide is a major breakthrough for achieving low-loss lightwave propagation at subwavelength size. Various types of passive hybrid plasmonic waveguides have been reported, but research on active hybrid plasmonic waveguides is very limited. In this study, we propose a tunable hybrid plasmonic waveguide in which its modal characteristics could be dynamically tuned by manipulating the evanescent field of a dielectric waveguide using a closely suspended tuning waveguide. The device can obtain a long-distance lightwave propagation at centimeter scale while maintaining the propagation mode at deep-subwavelength size (2.44??2/105). Using the proposed tuning method, the propagation length can be tuned more than 100% at the same propagation mode area. The proposed device with a propagation length that can be tuned in a wide range is a promising candidate for building active photonic components.
关键词： Tunable hybrid plasmonic waveguide,Long-distance lightwave propagation,Deep-subwavelength mode size,Evanescent field manipulation
更新于2025-09-16 10:30:52
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A New Hybrid Finite Element Method: Electromagnetic Propagation in Bent Waveguides
摘要： A new hybrid ?nite element method (HFEM) was developed, using basis functions of ?rst and second order, to analyse the electromagnetic wave propagation in three types of waveguides: disk waveguides, ring waveguides and cylindrical waveguides. For validation purposes, results obtained with the HFEM method were compared with those obtained with a recursive ?nite element method (RFEM) and with two different analytical methods. The domain discretization effect on the results of the new HFEM method was examined using either a uniform distribution of nodes or a Delaunay distribution method. The results show that the Delaunay method, used in the mesh de?nition, is important, not only to assure the reliability of the method but also to signi?cantly reduce the computation time and memory consumption. Also, the in?uence of the distance between the ?ctitious boundary and the waveguide core was analysed showing an important effect on the result numerical accuracy. In conclusion, results show that the new hybrid ?nite element method presented has a signi?cant advantage on calculation time over the recursive ?nite element method.
关键词： electromagnetic ?eld propagation,?nite element method,Bent waveguides
更新于2025-09-16 10:30:52
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Effects of channel alternating corrugation on a laser beam propagation in plasmas
摘要： The propagation of an intense laser beam in an alternating corrugated plasma channel, which has a wide region and a narrow region in one corrugated space period, is investigated. Compared with the usual corrugated plasma channel, it is found that there are many more resonance peaks and many more abundant beat-like wave phenomena for the laser beam in this extended channel. Moreover, the much narrower region in some special alternating corrugated channels can play the role like a plasma lens for some laser beams, i.e., it can obviously change the laser spot size from small (large) to large (small) amplitude when the laser passes through the narrow region. These results are well confirmed by the final numerical simulations of wave equation and particle-in-cell approach.
关键词： Laser beam,Conversion,Resonance,Corrugated plasma channel,Propagation characteristics,Beat-like wave
更新于2025-09-16 10:30:52
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Numerical Investigation on the Influence of Water Vapor Ionization on the Dynamic and Energy Deposition of Femtosecond Ultraviolet Laser Filamentation in Air
摘要： The e?ects of water vapor ionization on the nonlinear propagation of femtosecond laser pulses with a 248 nm wavelength are numerically investigated in this paper. It is found that ionization of H2O molecules plays a signi?cant role in air ionization, which seriously a?ects the dynamic and energy deposition of ?lamentation. The propagation of femtosecond pulses in air with di?erent humidity levels are compared. The total number of electrons and total deposited pulse energy increase with the humidity increases. However, they tend to be saturated in high humidity conditions. Results presented here are conducive to characterizing the long-range propagation of ?laments under atmospheric conditions.
关键词： multiphoton absorption,atmospheric propagation,self-focusing,water vapor,ultrafast nonlinear optics
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Spontaneous bremsstrahlung of ultrarelativistic electrons within the resonant conditions in the field of a nucleus and external electromagnetic field
摘要： We have developed small-sized terahertz free-electron lasers by using low-cost and compact microtrons combining with magnetrons as high-power RF sources. We could stabilize the bunch repetition rate by optimizing a modulator for the magnetron and by coupling the magnetron with an accelerating cavity in the microtron. By developing high-performance undulators and low-loss waveguide-mode resonators having small cross-sectional areas, we could strengthen the interaction between the electron beam and the THz wave inside the FEL resonators to achieve lasing even with low-current electron beams from the microtron. We used a parallel-plate waveguide in a planar electromagnet undulator for our ?rst THz FEL. We try to reduce the size of the FEL resonator by combining a dielectric-coated circular waveguide and a variable-period helical undulator to realize a table-top THz FEL for applying it to the security inspection on airports.
关键词： submillimeter wave technology,free electron lasers,submillimeter wave propagation,electron beams,undulators,Electromagnetic radiation
更新于2025-09-16 10:30:52