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[IEEE 2018 IEEE 7th International Conference on Photonics (ICP) - Langkawi, Malaysia (2018.4.9-2018.4.11)] 2018 IEEE 7th International Conference on Photonics (ICP) - Design and Modelling of PANDA Ring Resonator Structure
摘要： We propose a PANDA ring resonator structure based on silicon on insulator material. Modelling is carried out using FDTD based simulation tool. The miniaturized structure of the proposed device makes it suitable for on chip nanophotonic applications. The effect of variation of ring radius and gap separation between the rings of the PANDA resonator structure on transmission characteristics is analyzed.
关键词： PANDA resonator,Ring resonator,Silicon photonics,Integrated photonics,FDTD
更新于2025-09-10 09:29:36
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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) - Accelerating Passive and Active Silicon Photonics Design using Multiple Numerical Techniques
摘要： This work compares three numerical techniques for modeling the optics of passive and active silicon photonic devices. A comparison of computation time revealed that a judicious choice of technique can lead to the reduction of design cycle time by orders of magnitude.
关键词： Waveguide Photodetector,Silicon Photonics,Spot size converter,EME,MMI,BPM,FDTD
更新于2025-09-10 09:29:36
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Ultracompact ultrafast-switching-speed all-optical 4?×?2 encoder based on photonic crystal
摘要： A novel two-dimensional photonic-crystal-based all-optical encoder was designed, tested, and optimized. The structure is built on a linear square-lattice photonic crystal platform. An ultracompact, simple design occupying an area of only 128.52 μm2 is constructed, 50 % smaller than the smallest design known to date. Ultrafast switching speed with the lowest known delay time is achieved. The proposed design consists of one ring resonator with cylindrical silicon rods suspended in air. No auxiliary or bias input is required for its operation. The proposed platform is not sensitive to the applied input phase shift. Finite-difference time-domain and plane-wave expansion methods were used to analyze the structure and optimize the radius of the rods at 1.525 μm, with radius of the inner rods of 0.19a, for successful operation, resulting in ultrafast switching speed of 10 THz and shorter delay time reaching 0.1 ps. This maximum switching speed is two times faster than recent literature reports. The contrast ratio is calculated to reach an acceptable record of 7.1138 dB. The trade-off between the switching speed and contrast ratio was also examined.
关键词： Line defect,Photonic crystal,Plane-wave expansion (PWE),Switching speed,Ring resonator,All-optical encoder,Finite-difference time-domain (FDTD) analysis
更新于2025-09-10 09:29:36
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EXTENSION OF THIN WIRE TECHNIQUES IN THE FDTD METHOD FOR DEBYE MEDIA
摘要： There are applications of the ?nite di?erence time domain (FDTD) method, which need to model thin wires in dispersive media. However, existing thin wire techniques in the FDTD method are developed only for the conductive and dielectric media. The article presents a modi?cation of oblique thin wire formalism proposed by Gui?aut et al. and a minor modi?cation for the technique proposed by Railton et al. for applications with Debye media. The modi?cations are based on auxiliary di?erential equation (ADE) method. The modi?cations are validated by calculations of grounding potential rise (GPR) of a horizontal electrode buried in soil with dispersive properties.
关键词： grounding potential rise,auxiliary di?erential equation,thin wires,Debye media,FDTD method
更新于2025-09-10 09:29:36
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Enhanced photocatalytic H2 evolution and phenol degradation over sulfur doped meso/macroporous g-C3N4 spheres with continuous channels
摘要： S-doped meso/macroporous g-C3N4 spheres (SMCN) were successfully synthesized via an in situ novel method utilizing millimeter-scale porous silica spheres as template and thiourea as precursor and S source. Such SMCN possessed millimeter-scale spherical morphology with continuous channels at 20e80 nm in the interior of the spheres, and exhibited increased H2 generation rate (15 times) and phenol degradation rate (5 times) under visible light irradiation compared with that over pristine g-C3N4, mainly due to the enlarged surface area, enhanced mass transfer and improved ef?ciency of charges separation all stemming from the synergetic effects of the S doping and pore creating. Notably, density functional theory (DFT) calculations were employed to further understand the mechanism of the photocatalytic enhancement with regard to the optical absorption property at atomic level. Combined with the ?nite difference time domain (FDTD) simulations aiming at evaluating the effect of the nanoscale pore architecture on the optical absorption ability, it was revealed that not only the S doping but also the meso/macroporous structure resulted in the enhancement of the optical absorption, which was considered to be an essential role for the enhanced photocatalytic performances over SMCN.
关键词： Continuous channels,FDTD simulation,Optical absorption,DFT,S-doping
更新于2025-09-10 09:29:36
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3D-FDTD modelling of optical biosensing based on gold-coated nanoporous anodic alumina
摘要： The suitability of using gold-coated nanoporous anodic alumina structures as a platform for reflectometry-based plasmonic biosensors is investigated by numerical simulation. Reflectance spectra of such structures has been obtained using 3D-FDTD while the sensing capabilities have been evaluated as the change in spectra upon the adsorption of a layer of a biological-related molecule (biolayer) on the gold coating and inner pore surface. Results show that the gold-coated nanoporous structure enables the coupling of normally incident light to a localized surface plasmon resonance, and that such resonance shifts upon the adsorption of the biolayer. A sensitivity can be defined as the resonance wavelength shift with the biolayer refractive index. It is demonstrated that smaller gold coating thicknesses result in an increase in sensitivity, but at the cost of a decrease in the resonance sharpness, what suggests the existence of an optimal gold coating thickness.
关键词： Gold-coated nanoporous anodic alumina,Biolayer,FDTD simulation,Reflectometry-based plasmonic biosensor
更新于2025-09-10 09:29:36
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Design of freely suspended photonic crystal microfiber cavity sensors array in a general single mode fiber
摘要： We propose a novel design of refractive index (RI) sensor array based on ultrahigh sensitivity one dimensional (1D) photonic crystal microfiber (PCMF) cavities, which is referred as photonic crystal microfiber cavity sensors array (PCMF-CSA). The proposed PCMF-CSA consists of multiple channels connected in parallel. A transmission only containing the fundamental mode (FM) resonance of the PCMF cavity sensor for sensing purpose is created by connecting an additional PCMF bandgap filter to a PCMF cavity sensor in series on each channel. Due to the photonic bandgap (PBG) of the PCMF bandgap filter, the other high-order resonances are filtered out. With proper engineering of the PBG, multiple ultrahigh sensitivity PCMF cavity sensors can be integrated into microarrays without resonance overlap, and be detected simultaneously between a single input optical fiber and a single output optical fiber without the need for complicated coupling systems. The concept was demonstrated with 7-channel PCMF cavity sensor array containing PCMF bandgap filters. By using three-dimensional finite-difference time-domain (3D-FDTD) method, the performance of the device was investigated theoretically. The simulation results showed that the sensors on each channels can be monitored simultaneously from a single output spectrum. The numerical calculated RI sensitivities (S) for each sensing channel of the proposal 7-channel PCMF-CSA as high as 647.33 nm/RIU, 666.67 nm/RIU, 662.00 nm/RIU, 676.00 nm/RIU, 674.67 nm/RIU, 659.33 nm/RIU, 679.99 nm/RIU can be achieved, respectively. The average RI sensitivity as high as 666.57 nm/RIU can be obtained. Moreover, the extinction ratios of all resonant peaks exceed 20.0 dB. The crosstalk of all channels is lower than ?24.5 dB. To the best of our knowledge, this is the first silica PCMF sensors array geometry based on conventional single mode fiber (SMF) that features both high Q and S, and thus is potentially a promising platform for ultra-sensitive RI-based gas sensing with high parallel-multiplexing capability.
关键词： Ultrahigh sensitivity,Photonic crystal,Multiplexing,Microfiber cavity,Sensors array,3D-FDTD
更新于2025-09-10 09:29:36
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Fast method for analysing nonlinear composite right/left-handed transmission lines based on finite-difference time-domain method
摘要： In this study, a new finite-difference time-domain (FDTD) scheme is presented for analysing nonlinear composite right/left-handed (CRLH) transmission lines, with reduction of the central processing unit time. A step by step analysis is demonstrated to solve the equations for nonlinear CRLH transmission lines based on the FDTD method. The proposed method is applied to a nonlinear CRLH transmission line as an example and the results are confirmed by those of the conventional FDTD method. The comparisons reveal that the presented solution efficiently decreases by about 82% of the computational time consumption.
关键词： finite-difference time-domain (FDTD),computational time reduction,nonlinear composite right/left-handed (CRLH) transmission lines
更新于2025-09-10 09:29:36
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One-Step Leapfrog LOD-FDTD Method With CPML for Periodic Structures
摘要： For high efficient analysis of an obliquely incident plane wave on periodic structures, one-step leapfrog locally one-dimensional (LOD-FDTD) method is proposed in this letter. Firstly, by applying the LOD scheme into the improved split-field algorithm, unconditional stability can be achieved. And then, by introducing three auxiliary variables, the one-step leapfrog implementation for the LOD scheme is derived. Finally, the implementation of the convolutional perfectly matched layer (CPML) for the proposed method is derived. At last, numerical results are given to verify the accuracy and efficiency of the proposed method.
关键词： leapfrog scheme,periodic structures,locally one-dimensional finite-difference time-domain (LOD-FDTD) method,unconditional stability
更新于2025-09-09 09:28:46
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Finite-difference time-domain method for calculating photoexcited molecular vibration wave-packet dynamics
摘要： We propose a simple numerical calculation method for solving molecular vibrational dynamics. A finite-difference time-domain (FDTD) method is utilized to solve the Schr?dinger equation for wave packet dynamics driven by incident light pulses. Vibrational wave function is discretized and divided into real and imaginary parts, and then the Schr?dinger equation is solved by temporally and alternately calculating the real and imaginary parts, in a similar manner to the conventional FDTD method. Taking generation of a hot molecule by pump-dump scheme and multi-photon excitation process as examples, we show the validity and usefulness of the proposed method. The dynamics of the vibrational wave packets in the pump-dump scheme and transient virtual excitations of intermediate vibronic state in the three-photon absorption can be easily visualized, and the intensity dependence of excitation population for ultra-high intensity beyond the perturbation theory can be accurately calculated.
关键词： pump-dump scheme,molecular wave-packet dynamics,multi photon absorption,FDTD method for quantum dynamics
更新于2025-09-09 09:28:46