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Photonics, Volume 5, Issue 4 (December 2018)

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Open AccessArticle Design of Silica Multimode Optical Fibers with Extremely Enlarged Core Diameter for Laser-Based Multi-Gigabit Short-Range Optical Networks
Received: 9 September 2018 / Revised: 5 October 2018 / Accepted: 8 October 2018 / Published: 16 October 2018
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Abstract
This work presents an alternative fast and simple method for the design of a refractive index profile of silica multimode optical fibers (MMFs) with extremely enlarged core diameters of up to 100 µm for laser-based multi-gigabit short-range optical networks. We demonstrate some results
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This work presents an alternative fast and simple method for the design of a refractive index profile of silica multimode optical fibers (MMFs) with extremely enlarged core diameters of up to 100 µm for laser-based multi-gigabit short-range optical networks. We demonstrate some results of 100 µm core MMF graded index profile optimization performed by a proposed solution, which provides a selected mode staff differential mode delay (DMD) reduction over the “O”-band under particular launching conditions. Earlier on, a developed alternative model for a piecewise regular multimode fiber optic link operating in a few-mode regime for the computation of laser-excited optical pulse dynamics during its propagation over an irregular silica graded-index MMF with an extremely large core diameter, is utilized to estimate the potentiality of fiber optic links with the described MMFs. Here, we also present the comparison results of the simulation of 10GBase-LX optical signal transmission over 100 µm core MMFs with conventional and optimized graded-index refractive index profiles. Full article
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Open AccessArticle Hairy Polydopamine Particles as Platforms for Photonic and Magnetic Materials
Received: 13 September 2018 / Revised: 9 October 2018 / Accepted: 11 October 2018 / Published: 12 October 2018
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Abstract
By selecting the core materials and grafted-hair polymers, hairy particles with polymer brushes can create various types of functional materials. In recent years, polydopamine (PDA) particles that are obtained by polymerizing dopamine, which is an amino acid derivative, have attracted attention for various
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By selecting the core materials and grafted-hair polymers, hairy particles with polymer brushes can create various types of functional materials. In recent years, polydopamine (PDA) particles that are obtained by polymerizing dopamine, which is an amino acid derivative, have attracted attention for various applications. Herein, we present a novel approach for creating photonic and magnetic materials from hairy PDA particles. By grafting a hydrophilic hair polymer, we have succeeded in producing photonic materials capable of structural color changes. Furthermore, we have demonstrated the preparation of magnetic materials by immobilizing holmium, which is one of the lanthanide elements, by electrostatic interactions onto a cationic hair polymer. These results demonstrate the possibility of hairy PDA particles for a wide range of applications, such as for photonic and magnetic materials. Full article
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Open AccessReview Disaster-Resilient Optical Network Survivability: A Comprehensive Survey
Received: 30 July 2018 / Revised: 3 September 2018 / Accepted: 7 September 2018 / Published: 12 October 2018
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Abstract
Network survivability endeavors to ensure the uninterrupted provisioning of services by the network operators in case of a disaster event. Studies and news reports show that network failures caused by physical attacks and natural disasters have significant impacts on the optical networks. Such
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Network survivability endeavors to ensure the uninterrupted provisioning of services by the network operators in case of a disaster event. Studies and news reports show that network failures caused by physical attacks and natural disasters have significant impacts on the optical networks. Such network failures may lead to a section of a network to cease to function, resulting in non-availability of services and may increase the congestion within the rest of the network. Therefore, fault tolerant and disaster-resilient optical networks have grasped the attention of the research community and have been a critical concern in network studies during the last decade. Several studies on protection and restoration techniques have been conducted to address the network component failures. This study reviews related previous research studies to critically discuss the issues regarding protection, restoration, cascading failures, disaster-based failures, and congestion-aware routing. We have also focused on the problem of simultaneous cascading failures (which may disturb the data traffic within a layer or disrupt the services at upper layers) along with their mitigating techniques, and disaster-aware network survivability. Since traffic floods and network congestion are pertinent problems, they have therefore been discussed in a separate section. In the end, we have highlighted some open issues in the disaster-resilient network survivability for research challenges and discussed them along with their possible solutions. Full article
(This article belongs to the Special Issue Lightwave Communications and Optical Networks)
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Open AccessArticle Holographic Fabrication and Optical Property of Graded Photonic Super-Crystals with a Rectangular Unit Super-Cell
Received: 25 September 2018 / Revised: 9 October 2018 / Accepted: 9 October 2018 / Published: 11 October 2018
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Abstract
Recently developed graded photonic super-crystals show an enhanced light absorption and light extraction efficiency if they are integrated with a solar cell and an organic light emitting device, respectively. In this paper, we present the holographic fabrication of a graded photonic super-crystal with
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Recently developed graded photonic super-crystals show an enhanced light absorption and light extraction efficiency if they are integrated with a solar cell and an organic light emitting device, respectively. In this paper, we present the holographic fabrication of a graded photonic super-crystal with a rectangular unit super-cell. The spatial light modulator-based pixel-by-pixel phase engineering of the incident laser beam provides a high resolution phase pattern for interference lithography. This also provides a flexible design for the graded photonic super-crystals with a different ratio of length over the width of the rectangular unit super-cell. The light extraction efficiency is simulated for the organic light emitting device, where the cathode is patterned with the graded photonic super-crystal. The high extraction efficiency is maintained for different exposure thresholds during the interference lithography. The desired polarization effects are observed for certain exposure thresholds. The extraction efficiency reaches as high as 75% in the glass substrate. Full article
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Open AccessReview New Generation Wearable Antenna Based on Multimaterial Fiber for Wireless Communication and Real-Time Breath Detection
Received: 31 August 2018 / Revised: 20 September 2018 / Accepted: 30 September 2018 / Published: 11 October 2018
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Abstract
Smart textiles and wearable antennas along with broadband mobile technologies have empowered the wearable sensors for significant impact on the future of digital health care. Despite the recent development in this field, challenges related to lack of accuracy, reliability, user’s comfort, rigid form
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Smart textiles and wearable antennas along with broadband mobile technologies have empowered the wearable sensors for significant impact on the future of digital health care. Despite the recent development in this field, challenges related to lack of accuracy, reliability, user’s comfort, rigid form and challenges in data analysis and interpretation have limited their wide-scale application. Therefore, the necessity of developing a new reliable and user friendly approach to face these problems is more than urgent. In this paper, a new generation of wearable antenna is presented, and its potential use as a contactless and non-invasive sensor for human breath detection is demonstrated. The antenna is made from multimaterial fiber designed for short-range wireless network applications at 2.4 GHz frequency. The used composite metal-glass-polymer fibers permits their integration into a textile without compromising comfort or restricting movement of the user due to their high flexibility, and shield efficiently the antenna from the environmental perturbation. The multimaterial fiber approach provided a good radio-frequency emissive properties, while preserving the mechanical and cosmetic properties of the garments. With a smart textile featuring a spiral shape fiber antenna placed on a human chest, a significant shift of the operating frequency of the antenna was observed during the breathing process. The frequency shift is caused by the deformation of the antenna geometry due to the chest expansion, and to the modification of the dielectric properties of the chest during the breath. We demonstrate experimentally that the standard wireless networks, which measure the received signal strength indicator (RSSI) via standard Bluetooth protocol, can be used to reliably detect human breathing and estimate the breathing rate in real time. The mobile platform takes the form of a wearable stretching T-shirt featuring a sensor and a detection base station. The sensor is formed by a spiral-shaped antenna connected to a compact Bluetooth transmitter. Breathing patterns were recorded in the case of female and male volunteers. Although the chest anatomy of females and males is different compared, the sensor’s flexibility allowed recording successfully a breathing rate of 0.3 Hz for the female and 0.5 Hz for the male, which corresponds to a breathing rate of 21 breaths per minutes (bpm) and 30 bpm, respectively. Full article
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Open AccessArticle Mid-Infrared Photonic-Crystal Surface-Emitting Lasers with InGaAs/GaAsSb ‘W’-Type Quantum Wells Grown on InP Substrate
Received: 10 September 2018 / Revised: 28 September 2018 / Accepted: 30 September 2018 / Published: 2 October 2018
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Abstract
InP-based InGaAs/GaAsSb ‘W’-type quantum well (QW) photonic-crystal (PC) surface- emitting lasers (SELs) of 2.2 μm wavelength range are fabricated and room-temperature lasing emissions by optical pumping are demonstrated for the first time. Photonic-crystal surface-emitting laser (PCSEL) devices are investigated in terms of PC
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InP-based InGaAs/GaAsSb ‘W’-type quantum well (QW) photonic-crystal (PC) surface- emitting lasers (SELs) of 2.2 μm wavelength range are fabricated and room-temperature lasing emissions by optical pumping are demonstrated for the first time. Photonic-crystal surface-emitting laser (PCSEL) devices are investigated in terms of PC parameters of etch depth, lattice period, and filling factor. The lasing emissions cover wavelengths from 2182 nm to 2253 nm. The temperature-dependent lasing characteristics are also studied in terms of lattice period. All PCSELs show consistent lasing wavelength shift against temperature at a rate of 0.17 nm/K. The characteristic temperatures of PCSELs are extracted and discussed with respect to wavelength detuning between QW gain peak and PC cavity resonance. Full article
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Open AccessArticle Time- and Phase-Domain Thermal Tomography of Composites
Received: 5 September 2018 / Revised: 24 September 2018 / Accepted: 26 September 2018 / Published: 28 September 2018
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Abstract
Active infrared (IR) thermographic nondestructive testing (NDT) has become a valuable inspection method for composite materials due to its high sensitivity to particular types of defect and high inspection rate. The computer-implemented thermal tomography, based on the analysis of heat diffusion in solids,
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Active infrared (IR) thermographic nondestructive testing (NDT) has become a valuable inspection method for composite materials due to its high sensitivity to particular types of defect and high inspection rate. The computer-implemented thermal tomography, based on the analysis of heat diffusion in solids, involves a specialized treatment of the data obtained by means of active IR thermographic NDT, thus allowing for the “slicing” of materials under testing for a few layers where discontinuity-like defects can be underlined on the noise-free background (binary thermal tomograms). The time-domain thermal tomography is based on the fact that, in a one-sided test, temperature “footprints” of deeper defects appear later in regard to shallower defects. The phase-domain tomography can be applied to collected IR data in a direct way, for instance, by using the Fourier transform, but quantification of results is more difficult because the relationships between phase and defect depth depend on experimental parameters, and the corresponding “phase vs. defect depth” calibration functions are ambiguous. In this study, the time- and phase-domain thermal tomography techniques have been compared on simulated IR thermograms and experimentally applied to the evaluation of carbon fiber reinforced plastic composite containing impact damage defects characterized by impact energy 10, 18, and 63 J. Both tomographic techniques have demonstrated similar results in the reconstruction of thermal tomograms and, in some cases, supplied complementary information about the distribution of single defect zones within impacted areas. Full article
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Open AccessArticle Coupled Chiral Optical Tamm States in Cholesteric Liquid Crystals
Received: 29 August 2018 / Revised: 21 September 2018 / Accepted: 26 September 2018 / Published: 28 September 2018
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Abstract
The modes formed by two coupled chiral optical Tamm states localized at the interfaces between a photonic cholesteric liquid crystal conjugated with polarization-preserving anisotropic mirrors have been analytically and numerically investigated. These modes are only excited at the diffracting polarization of incident light.
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The modes formed by two coupled chiral optical Tamm states localized at the interfaces between a photonic cholesteric liquid crystal conjugated with polarization-preserving anisotropic mirrors have been analytically and numerically investigated. These modes are only excited at the diffracting polarization of incident light. As the cholesteric layer thickness decreases, the spectral splitting of the localized state frequency is predicted. The splitting value depends on the crystal layer thickness. At the nondiffracting circular polarization, the localized modes are not excited, and the system becomes similar to the Fabry–Pérot cavity containing an anisotropic helical structure. Full article
(This article belongs to the Special Issue Nonlinear Dielectric Photonics and Metasurfaces)
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