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A combination of asymptotic and rigorous methods is used to compute the radar cross section of an aircraft with engine inlets that include fan blades. The engine inlet and the blades are solved rigorously with an integral-equation method while the aircraft is analyzed with an asymptotic method. A two-step process is proposed that is both accurate and fast.
We present the ultrashort pulse generation of sub-300 fs from a mode-locked Erbium doped fiber laser by using spin-coated graphene oxide and reduced graphene oxide saturable absorbers deposited onto polished surface of D-shaped optical fibers.
This paper presents a full three-dimensional carpet cloak design, whose invisibility is independent of the incident wave direction. The device is developed with transformation optics and three-dimensional quasi-conformal coordinate transformation, which is obtained through parametrization and numerical optimization. The anisotropy reduction was sufficient to consider the medium as isotropic and to...
We propose and experimentally demonstrate a spatially tunable phase-OTDR based distributed microphone for listening to the sound of multiple machines. The distributed acoustic sensing capability, allied with the real-time spatial tuning, enables listening to a drill and to a cooling water system pump placed in two different sections along a single optical fiber, one at a time. The recorded acoustic...
Experimental results of refractive index response of cascaded long period grating (CLPG) coated with polymethyl methacrylate (PMMA) are presented in this work. The response of the grating to environmental refractive index changes is investigated by grating immersion into glycerin-water blends with several concentrations. The results indicate that CLPG refractometers with PMMA nanocoating allow refractive...
In a recent study, a process for the generation of Extremely Low Frequency (ELF) waves in the range of 1–12 Hz produced by diamagnetic currents generated by heat in ionosphere by high frequency (HF) waves has been proposed. HF waves that reach the ionosphere can be generated, for example, on the Earth's surface by the High Frequency Active Auroral Research Program (HAARP) instruments or solar processes...
Delivery time of products for satellite payloads is increasingly becoming a key competitive factor for companies in the relevant industry sector. This paper discusses a new approach of joining standard waveguide segments such as flanges, bends and straight segments. With the combination of using both a pulsed laser system and wire freed drive along with a special holding mechanism, a complex aluminum...
We propose a new uniaxial chiral metamaterial which is composed of four crescent shaped split-ring resonators mutually twisted by 90° and patterned on opposite sides of a dielectric substrate. It illustrates a strong optical activity and circular dichroism in the range from 5 GHz to 10 GHz. The presented design can be fabricated more easily due to its efficient metallic structures. Furthermore, chirality...
The technique recommended to achieve adhesion of composites to the enamel and dentine in dentistry is incremental with gradual photo-activation. Bulk fill composites were developed to reduce the clinical time and shrinkage polymerization. There are two types of bulk fill composites according the viscosity. The present study evaluates the shrinkage and temperature change during the polymerization of...
We present the ultrashort pulse generation of 250 fs from a mode-locked Erbium doped fiber laser by using mechanically exfoliated graphite saturable absorbers deposited onto side-polished surface of a D-shaped optical fiber.
We present a low-cost embedded Optical Time Domain Reflectometer (OTDR) solution for link monitoring of direct modulation analog Radio over Fiber (a-RoF) systems transporting Long Term Evolution Advance (LTE-A) signals. Experimental results show that monitoring can be performed in-service and offline in order to detect fiber faults and quantify losses. A trade-off between the OTDR peak power and the...
We present a field demonstration of a distributed high birefringence localization based in POTDR-C (Polarization Optical Time Domain Reflectometer Converter). In such conception, a low cost converter is used after a commercial OTDR (Optical Time Domain Reflectometer) to reduce spectral line width of OTDR laser. This ensures high sensitivity to SOP (State of Polarization) changes due to local birefringence...
We experimentally demonstrate transmission of 20×50-Gb/s WDM PAM-4 channels over an 80-km uncompensated fiber link, based on reduced complexity DSP and hardware. BER values below pre-FEC limit of 3.8×10·3 are reported, validating the proposed architecture for low-cost, high-capacity short-reach connectivity.
This paper describes optimization of the constructive parameters of a high loss microstrip line using HFSS (High Frequency Structural Simulator) for the development of a hydrogen sensor. Palladium changes its conductivity with the absorption of H2. Thus, this work proposes the optimization of a high loss line of Pd for hydrogen detection. The detection is made considering the propagated signal variations...
In this investigation we report, to the best of our knowledge, the first realization of air-core optical fibers obtained by drawing a 3D printed preform. Two different optical fibers are presented. Descriptions on the preform preparation and fiber drawing are provided, and our preliminary results are presented.
With the rapid growth of wireless systems, studies involving electromagnetic wave absorbers have attracted great attention from researchers. Their applications range from indoor systems to military applications. In parallel with this growth, increasing studies on Frequency Selective Surfaces (FSS) allow their filtering properties to be applicable in several systems, such as reflecting antennas, bandpass...
Analog Radio-over-Fiber (a-RoF) has gained increasing attention in the context of next-generation optical networks due to its spectral efficiency and lower deployment cost. However, electro-optical conversion of the information signal is delicate since the non-linear characteristic of the electro-optical modulator's transfer function causes inter-channel interference and poses a severe limitation...
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