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Optical filtering devices in SiO2/AlGaAs superlattice structures
摘要： In this work, the properties of the photonic bandgap (PBG) and Omni-directional photonic bandgap (Omni-PBG) of a quasi-one-dimensional photonic crystal (PC) are studied, in both TE and TM polarization modes. The PC is made of SiO2 and AlxGa1?xAs layers, alternatively, where x is the content of aluminum atoms in the GaAs slab. Using the transfer matrix method (TMM), the calculations are carried out within Maxwell’s equation framework, to express the magnetic field of each medium in terms of electric. This model reduces the numerical calculation time and enables us to investigate the PBG and the Omni-PBG properties in the superlattices. We show that by varying the content and geometrical parameters, one can easily block the transmittance of the electromagnetic wave in the PC. The numerical results may be useful in designing of optical filtering nano-devices.
关键词： Omni-directional photonic bandgap (Omni-PBG),Photonic crystal (PC),Photonic bandgap (PBG),Transfer matrix method (TMM)
更新于2025-09-23 15:21:21
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Optimization of PBG-Waveguides for Terahertz-Driven Electron Acceleration
摘要： The properties of 2-D photonic bandgap dielectric structures, also called photonic crystals, are numerically investigated to assist the design of waveguides for terahertz (THz)-driven linear electron acceleration. Given the broadband nature of the driving pulses in THz acceleration regimes, one design aim is to maximize the photonic bandgap width to allow propagation of the relevant frequencies within the photonic crystal linear defect waveguide. The proposed design is optimized to provide the best compromise between effective acceleration bandwidth and strong beam–wave interaction at the synchronism central frequency. Considerations on achieved acceleration bandwidth, accelerating voltage, and surface magnetic field are given to compare the proposed geometry to one of the main counterparts in the literature—the dielectric-lined waveguide.
关键词： Photonic crystals,terahertz (THz) electron acceleration,photonic-bandgap waveguides (PBG-Ws)
更新于2025-09-23 15:21:01
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Parasitic-coupled high-gain graphene antenna employed on PBG dielectric grating substrate for THz applications
摘要： In THz frequency region, the high-gain miniaturized patch antenna is essential to overcome the atmospheric losses. A novel dual-band miniaturized graphene antenna array with parasitic-coupled feed and mounted on PBG dielectric grating substrate is proposed in the operating frequency band from 0.85 to 1.04 THz. The analysis of graphene surface conductivity, surface wave polariton (SPP) of photonic band gap (PBG) substrate, and the dielectric grating substrate has been done for the verification of a projected design. Parametric analysis of PBG radius, periodic perturbation of dielectric grating substrate, and mutual coupling distance has been verified to achieve the enhanced radiation characteristics of the antenna. The minimum return loss of ?52.58 dB, VSWR of 1.005, impedance bandwidth of 33.34 GHz, the peak gain of 16.4 dB, and peak directivity of 17 dBi the projected design. The parasitic-coupled method is suitable to reduce the complexity of the antenna array and proposed design is useful in imaging, security using spectroscopy, and wireless communication applications.
关键词： parasitic coupling,PBG,dielectric grating,graphene,THz band
更新于2025-09-11 14:15:04
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Quantitative Analysis of Photon Density of States for One-Dimensional Photonic Crystals in a Rectangular Waveguide
摘要： Light propagation in one-dimensional (1D) photonic crystals (PCs) enclosed in a rectangular waveguide is investigated in order to achieve a complete photonic band gap (PBG) while avoiding the difficulty in fabricating 3D PCs. This work complements our two previous articles (Phys. Rev. E) that quantitatively analyzed omnidirectional light propagation in 1D and 2D PCs, respectively, both showing that a complete PBG cannot exist if an evanescent wave propagation is involved. Here, we present a quantitative analysis of the transmission functions, the band structures, and the photon density of states (PDOS) for both the transverse electric (TE) and transverse magnetic (TM) polarization modes of the periodic multilayer heterostructure confined in a rectangular waveguide. The PDOS of the quasi-1D photonic crystal for both the TE and TM modes are obtained, respectively. It is demonstrated that a “complete PBG” can be obtained for some frequency ranges and categorized into three types: (1) below the cutoff frequency of the fundamental TE mode, (2) within the PBG of the fundamental TE mode but below the cutoff frequency of the next higher order mode, and (3) within an overlap of the PBGs of either TE modes, TM modes, or both. These results are of general importance and relevance to the dipole radiation or spontaneous emission by an atom in quasi-1D periodic structures and may have applications in future photonic quantum technologies.
关键词： TE,PDOS,photonic crystals,waveguide,photonic band gap,TM,complete PBG
更新于2025-09-11 14:15:04
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[IEEE 2018 International Conference on Current Trends towards Converging Technologies (ICCTCT) - Coimbatore, India (2018.3.1-2018.3.3)] 2018 International Conference on Current Trends towards Converging Technologies (ICCTCT) - Design and Analysis of Optical Logic Gate using Two Dimension Photonic Crystal
摘要： In this paper, AND Logic gate functions are realized in a hexagonal lattice using 2D photonic crystal. The proposed logic gate is formed by the combination interference resonance phenomenon. Initially, the AND gate is designed without reference input which is considered as a two input logic gate and followed by another structure of photonic crystals with reference input is designed and its named as three input logic gate. The performance of proposed AND Logic gate structure is simulated by using 2D FDTD method. The simulation results show that the contrast ratio for two input AND gate and three input AND gate are 6.64 dB and 10.96 dB, respectively.
关键词： AND,Interference,Resonance,PBG Logic gates,Photonic crystal
更新于2025-09-09 09:28:46