Guided waves play a crucial role in non-destructive testing, offering a reliable and efficient means for inspecting structures and materials. In this paper, we present the implementation of a wave finite element metho...
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Guided waves play a crucial role in non-destructive testing, offering a reliable and efficient means for inspecting structures and materials. In this paper, we present the implementation of a wave finite element method for extracting dispersion curves, providing a feasible approach for analysing guided wave propagation in structures characterized by complex geometries and diverse material properties. Various numerical examples are investigated, including layered composites, functionally graded materials, rail sections, and metastructures, showcasing the versatility of the method. Mode sorting is a serious problem associated with this method crucial for distinguishing different guided wave modes. A mode sorting algorithm based on modal assurance criteria is implemented which can effectively trace different guided wave modes. To enhance accuracy, dispersion calculations are assisted by incorporating micro -modelling techniques for composite materials. Furthermore, the influence of initial stress on dispersion curves is examined, revealing that the effects of tensile and compressive stresses can vary at different frequencies and for different modes. Attenuation or damping is inherent in every structure and material, significantly influencing wave propagation. The article also investigates viscoelasticity and damping, expanding the method's applicability by introducing a novel approach to calculate attenuation using the frequency domain modulus for computing complex angular frequencies. The present method offers a fast, accurate, and feasible solution for extracting dispersion curves in structures with intricate geometries and material properties.
Nonlinear optical processes lie at the heart of frequency tunable coherent light sources, including entangled photon sources and squeezed states of light, and they have become ubiquitous in fields ranging from ultrafa...
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Nonlinear optical processes lie at the heart of frequency tunable coherent light sources, including entangled photon sources and squeezed states of light, and they have become ubiquitous in fields ranging from ultrafast spectroscopy to quantum information processing. van der Waals materials have recently emerged as dynamically tunable and highly nonlinear optical platforms with ultracompact footprints. In particular, semiconducting materials like transition metal dichalcogenides possess large optical nonlinearity, orders of magnitude higher than standard nonlinear bulk crystals, and promise interesting opportunities toward the miniaturization of nonlinear optical devices down to the nanoscale. In this Perspective, we outline ongoing and future research directions in the field of nonlinear optics with layered semiconductors, with special focus on the control and tunability of their optical nonlinearities.
Valley kink states and valley-polarized chiral edge states, whose topologically protected one-way propagation property provides a promising solution for manipulating light waves, have recently attracted considerable a...
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Valley kink states and valley-polarized chiral edge states, whose topologically protected one-way propagation property provides a promising solution for manipulating light waves, have recently attracted considerable attention in topological photonics. However, it remains a great challenge to realize flexibly tunable dispersion for two different topological states and to develop a dynamically controllable topological photonic platform for switching topological wave routing. In this work, we propose a reconfigurable topological wave routing structure in the telecommunication frequency range, where phase-change material Sb2S3 2 S 3 cylinders with tunable refractive index are embedded into each topological channel to dynamically tune the dispersion of topological edge states. Via switching the phase states of Sb2S3 2 S 3 between amorphous and crystalline, we numerically demonstrate some unique applications of the proposed topological photonic crystals, such as topological optical switches, dual-channel selective transport, and controllable multi-channel intersection waveguides. More importantly, by digitally encoding each waveguide channel without the requirement of controlling each unit cell in the bulk domain, the proposed topological photonic platform provides a convenient and easy-to-implement solution for achieving dynamically reconfigurable topological wave routing propagation. Besides, the unique features of immunity against bending interface with disorders demonstrate the robustness of the topological wave propagation. Our proposed topological photonic platform has potential applications for designing intelligent photonic devices and opens up an avenue for advanced integrated photonic systems with reconfigurability. (c) 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement
We investigate the quasi-coherent radiation from a train of electron bunches moving along the axis of a cylindrical waveguide, assuming that a part of the waveguide is filled with a dielectric medium. For the permitti...
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We investigate the quasi-coherent radiation from a train of electron bunches moving along the axis of a cylindrical waveguide, assuming that a part of the waveguide is filled with a dielectric medium. For the permittivity of the latter, the general case of dispersion is considered. It is shown that under certain conditions on the permittivity of the medium and on the values of the problem parameters, the waveguide modes become equidistant. As a consequence, quasi-coherent Cherenkov radiation from the train of bunches may be generated on the first several waveguide modes simultaneously. An example of dispersion law is provided for which the corresponding Cherenkov radiation is suppressed.
Interest is rising in improving efficiency and productivity by increasing the received signal power, which is driven by the proliferation of wireless local area networks and the increasing use of portable computing de...
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Interest is rising in improving efficiency and productivity by increasing the received signal power, which is driven by the proliferation of wireless local area networks and the increasing use of portable computing devices such as laptops and PDAs. waveguides comprising frequency selective surfaces are suggested for use in indoor wireless environments, and their impact on the propagation of radio waves is examined in this paper. Additional battery power and a link budget buffer are required for the obstructed (OBS) path because the received power is more attenuated than the line-of-sight path. Additionally, this study proposes a novel model for selectively improving radio propagation in confined spaces under OBS circumstances by reflecting channel radio waves into target regions, thus avoiding significant propagation loss. Finally, a small-scale interior environment has been built and tested in a half-wave chamber and a real room to demonstrate the idea in practice using ray tracing techniques.
Terahertz (THz) modulators are crucial components in terahertz high-speed communications and interconnections. In this article, we demonstrate a high-efficiency broadband terahertz graphene composite modulator. The mo...
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Terahertz (THz) modulators are crucial components in terahertz high-speed communications and interconnections. In this article, we demonstrate a high-efficiency broadband terahertz graphene composite modulator. The modulator is composed of a double-layer graphene integrated Si slot waveguide on a SiO2 substrate, which significantly enhances in-plane polarization matching and interaction between graphene and the THz wave. The transmission characteristics of the guided THz wave can be flexibly tuned by controlling the chemical potential of graphene. The modulator achieves excellent amplitude modulation performance, with a modulation depth of 99%, insertion loss of 0.0051 dB/mu m, modulation length of 300 mu m, modulation bandwidth of 19.59 GHz, and energy consumption of 384.5 pJ/bit at 1 THz. This work offers a potential solution for designing high-performance graphene-based THz modulators, with promising applications in future high-speed THz telecommunication and interconnect systems.
The laser generation characteristics of microdisc lasers with optically coupled waveguide operating in continuous wave mode at elevated temperatures are investigated. Laser generation and waveguide effect at temperatu...
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The laser generation characteristics of microdisc lasers with optically coupled waveguide operating in continuous wave mode at elevated temperatures are investigated. Laser generation and waveguide effect at temperatures up to 92.5 degrees C were demonstrated. The measured characteristic temperature of microlasers was 65 K in the range of 25-92.5 degrees C.
We report a Ta2O5 photonic platform with a propagation loss of 0.49 dB/cm at 1550 nm, of 0.86 dB/cm at 780 nm, and of 3.76 dB/cm at 2000 nm. The thermal bistability measurement is conducted in the entire C -band for t...
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We report a Ta2O5 photonic platform with a propagation loss of 0.49 dB/cm at 1550 nm, of 0.86 dB/cm at 780 nm, and of 3.76 dB/cm at 2000 nm. The thermal bistability measurement is conducted in the entire C -band for the first time to reveal the absorption loss of Ta2O5 waveguides, offering guidelines for further reduction of the waveguide loss. We also characterize the Ta2O5 waveguide temperature response, which shows favorable thermal stability. The fabrication process temperature is below 350 degrees C, which is friendly to integration with active optoelectronic components.
We investigate the formation of multipole topological solitons at the edges of two and three coupled parallel Su-Schrieffer-Heeger (SSH) waveguide arrays. We show that independent variations of waveguide spacing in th...
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We investigate the formation of multipole topological solitons at the edges of two and three coupled parallel Su-Schrieffer-Heeger (SSH) waveguide arrays. We show that independent variations of waveguide spacing in the unit cells (dimers) in coupled waveguide arrays result in the emergence at their edges of several topological edge states with different internal symmetries. The number of emerging edge states is determined by how many arrays are in topologically nontrivial phase. In the presence of nonlinearity, such edge states give rise to families of multipole topological edge solitons with distinct stability properties. Our results illustrate that coupling between quasi-onedimensional topological structures substantially enriches the variety of stable topological edge solitons existing in them. (c) 2024 Optica Publishing Group. All rights, including for text and data nologies, are reserved.
This paper reports on the fabrication and characterization of waveguides inside of a dye doped-organic/inorganic bulk material using femtosecond laser microfabrication. Rhodamine B-doped GPTS/TEOS-derived organic/sili...
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This paper reports on the fabrication and characterization of waveguides inside of a dye doped-organic/inorganic bulk material using femtosecond laser microfabrication. Rhodamine B-doped GPTS/TEOS-derived organic/silica monolithic xerogels with excellent optical quality were prepared by sol-gel method. The influence of the dye concentration on the samples optical properties was also investigated in order to choose the proper one to be used for producing the waveguides. After investigation of parameters to fabrication in xerogels, such as, scan speed effects and pulse energy, we produced waveguides in bulks doped with 0.5 mmol/L of Rhodamine B. Propagation losses in the single mode waveguides, at 632.8 nm wavelength, were obtained. (C) 2015 Elsevier B.V. All rights reserved.
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