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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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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - On the Possibility of Structural Characterisation of Hollow Core Fibres using Whispering Gallery Modes Excited by Laser and Broadband Light
摘要： Significant progress has been made in recent years in driving down the loss of hollow core fibres (HCFs), such as photonic bandgap fibres (PBGF), antiresonant nodeless fibres (ANF), and nested antiresonant nodeless fibres (NANF) towards that of their conventional solid single mode counterparts. In order to achieve the ultimate performance of HCFs, an accurate control of the dimensions and symmetry of the internal constituent elements is key in both the assembled preforms and drawn canes and fibres. Non-destructive optical methods to monitor and assess the internal features of HCFs over the entire fabrication process are therefore of great interest. Previously, morphology dependent resonances [1] and whispering gallery modes (WGMs) [2], excited by side illumination of the fibre, have been used to enable the precise measurement of cladding diameter variations with an accuracy greater than that of competing interferometric approaches. Motivated by this earlier work we have started studies into the opportunities provided by side illumination of HCF canes and fibres being drawn, and report some of our initial observations, which we hope will ultimately provide useful information on the internal features of HCFs.
关键词： whispering gallery modes,nested antiresonant nodeless fibres,hollow core fibres,photonic bandgap fibres,antiresonant nodeless fibres
更新于2025-09-12 10:27:22
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Photonic Bandgap Bragg Waveguide-based Terahertz Microfluidic Sensor
摘要： A 3D printed photonic bandgap Bragg waveguide-based resonant fluidic sensor operating in the THz spectral range is theoretical analyzed and experimental studied. The liquid analytes injected into a microfluidic channel inside the reflector region result in anticrossing of the dispersion relation between the core-guided mode and the defect state. By tracking the spectral positions of the induced absorption dips and phase changes on the transmission spectra, the fluidic sensor exhibits a sensitivity of 110 GHz/RIU and a resolution of 0.0045 RIU. The sensor provides a non-contact measurement method for real-time monitoring of the refractive index change of liquid flow in practical applications.
关键词： 3D Printing,Photonic Bandgap,Microfluidic Sensor,Bragg Waveguide,Terahertz
更新于2025-09-11 14:15:04
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Integrated Metamaterial Interfaces for Self-Aligned Fiber-to-Chip Coupling in Volume Manufacturing
摘要： Improving the scalability and cost efficiency of photonic packaging is central to fulfilling the silicon photonic promise of low-cost devices with unprecedented optical complexity. A key enabler towards this goal is an efficient, large-mode, integrated fiber coupler and mode converter. Using standard fiber modes at fiber-to-chip junctions avoids expensive in-fiber mode conversion and relaxes alignment tolerances for low-cost assembly and improved reliability. Metamaterial waveguides, also called subwavelength gratings, are particularly useful for such structures. They provide unmatched design flexibility and, counter-intuitively, are more forgiving to fabrication tolerances than solid-core waveguides. Here, we summarize our work on interfacing self-aligned, standard cleaved fibers to rectangular Si routing waveguides. Fiber V-grooves are integrated on chip with metamaterial converters embedded in suspended oxide membranes to prevent coupler-mode leakage to the substrate. We show optical results from first integration of V-grooves with metamaterial converters to commercial structures fabricated in 300 mm CMOS production facilities. We demonstrate a peak transmission of -0.7 dB on the TE polarization and -1.4 dB on the TM polarization with a respective spectral roll-off of 0.3 and 0.4 dB over the 60 nm bandwidth measured.
关键词： photonic bandgap materials,packaging,optical fiber communication,integrated optoelectronics
更新于2025-09-11 14:15:04
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Gas Sensing Mechanism of Silica with Photonic Bandgap Shift
摘要： Two physical models, Replacing model and Filling model, have been proposed to explain the mechanism of effective refractive index change of photonic crystals (PCs). Theoretically, photonic bandgap (PBG) would shift when PCs are exposed to different environment, which leads to change of effective refractive index of PCs. However, the mechanism of effective refractive index change is distinct when PCs are placed in different gases or vapors. Here, silica PCs were successfully fabricated by self-assembled method. The PGB of silica PCs exhibit similar redshift in volatile organic compounds (VOCs) or small-molecule gases. We propose Replacing model to elaborate silica PCs exposed to VOCs, while Filling model to explain silica PCs exposed to small-molecule gases. Additionally, the redshift of PBG was transformed into volume fraction of adsorbed gas in order to achieve selective sensing of silica PCs. The approach could be exploited for application in sensing.
关键词： refractive index,photonic crystals,photonic bandgap,silica,gas sensing
更新于2025-09-10 09:29:36