Optical Poster — 01 / Tuesday, August 29th / 11:20—13:00 / Esmeralda Room
We experimentally demonstrate a 56-GBd PAM4 transmission in a single wavelength at 1550 nm, without chromatic dispersion compensation in the optical domain, focusing on short-reach intra data center applications. We obtained an extended-reach of 33% employing low-complexity digital equalizers and maximum likelihood sequence estimation, achieving an error-free operation up to 4 km, considering 7% of FEC-overhead.
This paper presents an experimental demonstration of an all optical fast Fourier transform (FFT) technique, based on optical interferometry, applied for the dropping of an optical orthogonal frequency division multiplexing (OFDM) carrier. The OFDM signal, comprising an aggregate rate of 75 Gb/s quadrature phase shift keying (QPSK) modulation, was generated from an optical comb, with 12.5 GHz channel spacing, provided by the gain-switching of a semiconductor laser. The experimental results were then used to calibrate a system simulator where an all-optical Inverse FFT was included for the adding of an optical OFDM carrier. A synchronism mechanism was also configured in the simulation setup. The obtained bit error rate (BER) performance below the forward error corrector (FEC) limit for both, experimental and simulated, implementations demonstrate the node architecture potentiality for the optical processing of a superchannel with carrier spectral overlapping.
In this paper we investigate the impact of the fiber types arrangement on the performance of bidirectional mixed-fiber optical links. It is shown how to compose an optical link given a set of different fiber types in order to optimize the transmission bit error rate (BER). To this aim, a nonlinear interference noise (NLIN) theoretical prediction model was adapted to take into account different fiber types and their positions in the optical link. The analysis was performed considering a coherent wavelength-division multiplexing (WDM) transmission systems scenario, with no inline dispersion compensation.
The impact of the electrical phase modulation index 2πh in the performance of coherent detection optical OFDM systems based on electrical constant-envelope signals is analytically and numerically evaluated in this paper. A compromise between 2πh and system performance, that considers the effect of non-linearities inserted by Mach-Zehnder optical modulators, is established. Moreover, it is shown that this type of peak-toaverage power ratio (PAPR) reduction technique reduces the impact of the optical modulation index in the performance.
We show the design of a DAC-less PAM-4 optical modulator operating at 1550 nm wavelength based on integrated silicon waveguides embedded with graphene in capacitor-like structures on the top and below the waveguide's core. By balancing the optical modal distribution interacting with the graphene through the waveguide design, it is possible to perform direct modulation of PAM-4 signals aiming the next generation of integrated photonic devices for datacenters and interconnections. We evaluate the device's performance through numerical simulations taking into account the modulation depth, bandwidth, footprint, drive voltages and power consumption. These parameters are functions of graphene's length along the device and for a compact device with a 40 µm-long waveguide, 6 dB modulation depth and >50 Gb/s bitrates with sub-pJ per bit power consumption was calculated. The results achieved are promising for the next generation of integrated photonic devices, showing higher bit rates, smaller footprints and lower power consumption compared to the so far proposed DAC-less modulators based on silicon photonics.
Physical layer encryption (PLE) is a promising technology for increasing the security of communication networks. An important goal of PLE is to establish a mechanism that allows authorized users to understand cyphered messages. In this work, we show that this objective may be successfully accomplished by applying a double-lock strategy to the recently proposed optical spectral phase and delay encoding (SPDE) technique. The main feature of this strategy is that authorized users do not need to exchange a cryptographic key to achieve a safe communication. Computer simulation results suggest this double lock approach may be effectively used by metropolitan area network end users deploying SPDE encrypted 100 Gb/s signals.
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.
The acousto-optic properties of a double-core optical fiber are numerically investigated. The behavior of the power propagation, the transmission spectrum and the acoustically induced strain in the fiber is simulated using the 3D finite element method. The results indicate a promising first approach for the design of acousto-optic devices in complex fiber geometries.
In this paper, a two-dimensional polarization beam splitter based on transformation optics is proposed. A quasi-conformal mapping is applied resulting in a medium with inhomogeneous uniaxial permittivity and without magnetic response, which can facilitate the manufacturing process. The developed technique allows the design of arbitrary polarization splitting geometries, including asymmetrical geometries for each polarization independently. An example design of a compact splitter with 110 µm2 and orthogonally oriented outputs is presented and validated through numerical simulations, showing insertion loss below 0.03 dB.
Integrated optical phase modulators based on silicon waveguides with graphene are optimized through the design of the waveguide for operation with quasi-TE or quasi-TM modes using numerical simulations. Higher performance is achieved for quasi-TM mode operation with VπL=0.5 V.mm and for the quasi-TE mode VπL=0.9 V.mm, electro-optical bandwidths up to 2.85 GHz is achieved.
This manuscript presents computational modeling of the transducer elements of temperature sensors using the surface plasmon resonance (SPR) effect in a D-shaped single-mode fiber (SMF). The modeling is made in two independent ways: i) an analytical model based on the Fresnel's formulation and ii) a numerical model based on the finite element method. Both models describe the modulation of the transmitted optical signal within the D-shaped SMF using the attenuated total internal reflection method. Results show the modulation of the optical signal as a function of temperature on the D-shape, which is composed of a metallic thin film and liquid fluids. The obtained results show a good agreement between the models and an estimated measurement temperature resolution of 0.035 °C for an operating dynamic range of about 20 °C at different central temperatures, depending on the liquid fluid used.
The transient and steady state performances of optical space switches based on semiconductor optical amplifiers (SOAs) switching an optical carrier modulated in amplitude through several switching techniques and operating parameters were characterized. The analysis was focused on the switch's guard time, resulting from the sum of its rise time and ringing time, and the switching amplitude, related with the modulated bits vertical opening when the switch is at ON or OFF operating states and the switching pulse optical amplitude. The results point to the SOA optimum operating region, in relation to the analyzed parameters, which is defined by low bias current (between 60 mA and 80 mA) and high step amplitude (above 2 V).
In this work, we present a numerical design of an air-core vortex polymer optical fiber in CYTOP (Cyclic Transparent Optical Polymer) with a diameter of 16 um that can stably propagate up to 14 OAM states at a visible wavelength of 633 nm. The coupling coefficients are lower than -50 dB considering ellipticities less than 2% that could come from diameter variations induced in the fabrication process. Our vortex fiber seeks to be an alternative for increasing the capacity of short-range optical communication systems multiplexed by modes, in which there is a huge demand of low cost and easy to handled fibers.
In this work we analyse properties of symmetric devices with magnetic media by using magnetic group tools. The point-group theory has been used frequently to describe electromagnetic responses of nonmagnetic symmetric components. In a structure with magnetic medium biased by a magnetic field, usually some of the symmetry transformations of the corresponding nonmagnetic component are lost and non-unitary transformations appear. This changes the algebraic structure of the group and also changes its representations. We develop method of application of the theory of corepresentations of magnetic groups using as an example a current density modes in a magnetized graphene array described by magnetic symmetry C2v(C2).
We present a heuristic algorithm to address the optimization problem of routing and spectrum allocation, aimed at traffic protection and restoration in an elastic optical network. The algorithm searches for working and backup disjoint paths, using the shared path protection scheme. It divides the spectrum into two partitions and prioritizes slots in one of them to backup path traffic. The way the algorithm occupies slots of the working and backup paths resembles the behavior of two inverted stacks in which their slots are filled from the extremities toward the center. This scheme is effective in improving the blocking probability of connection requests, spectrum utilization ratio, and average size of slot groups. Comparison with reported algorithms shows good performance of the proposed approach.
We present a novel shared backup path protection algorithm for all-optical networks which considers the physical layer impairments and limits for the number of times that a backup wavelength can be used to protect a set of active lightpaths. Moreover, we propose a strategy to evaluate the trade-off between the vulnerability ratio, protection ratio and blocking probability using the dominance criterion. Our proposal outperformed three other well known approaches presented in the literature.
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 data transmission power has been identified; nevertheless, it is proven that with proper configuration of the system, the required values of Error Vector Magnitude (EVM) for different modulation formats are not surpassed. Offline monitoring using this configuration setup showed a Dynamic Range of ~24 dB with 10 meters spatial resolution.
In this work we demonstrate how the formalism of Hopf fibration can be useful in the context of classical coherent optical communications. We have found that the Hopf maps can provide complementary information on the geometry of four-dimensional signal space through explicit and concise relations. Using the sampled discrete Hopf fibration, we designed a dense 4D modulation called 14PolSK-8QAM and for practical purposes we demonstrate the close relationship between the Hopf maps and the transfer function of the Polarization Multiplexed Quadrature Mach-Zehnder modulators.
In this paper, we propose an approach to separate the temperature and strain information in a single fiber BOTDA system. The basis of this method is a mathematical theory to invert non-square matrices, called as Moore-Penrose pseudo-inverse. The system was tested both theoretically and experimentally in order to compare the use of a single optical band used to make a multi-wavelength measurement with other reference, which used two optical bands (O and C). The results demonstrated that this approach is suitable for recovering the temperature and strain data.
RF Poster — 01 / Tuesday, August 29th / 11:20—13:00 / Esmeralda Room
In this paper a frequency selective surface, FSS, based on open trapezoidal rings geometry is presented. Composed of four independent open rings, the geometry's characteristics are described and its frequency response discussed, including the polarization effects and how the pairs of rings are excited. Initial project equations are proposed for the first two resonant frequencies. Although these equations are an approximation, a first step for a numerical optimization, differences less than 6% were obtained, when compared to measured resonant frequencies. One advantage of the proposed FSS is the possibility of adjust almost separately the frequency response associated to each pair of open trapezoidal rings. Four FSS were fabricated and characterized, with numerical and measured results verifying a very good agreement. The ease of design, the achieved results, as well the possibility of integrating the open trapezoidal rings with other geometries, instigate the use of the proposed FSS in application such as smart electromagnetic buildings, reconfigurable FSS and so forth.
A novel single-layer dual-band FSS with angular stability is proposed in this paper. The proposed FSS is a junction of the Koch curve with the Ericampos multifractal geometry. The FSS functioning as stop band filter for satellite application at S- and X-Bands. The proposed FSS exerts high angular stability and the same response for both TE and TM operation modes because of it's inherently symmetry. The validation of the proposed structure was verified through measurements. A good agreement between numerical and experimental results is obtained.
Superluminal group velocities, i. e., velocities greater than the speed of light in vacuum, infinite or even negative, have been experimentally observed in the optical, electronic, and microwave domains. Such velocities in no way contradict special relativity because group velocity does not represent, in general, the velocity of a signal or information. Although it may seem counterintuitive, superluminal phenomena and the resulting negative-group-delay (NGD) effects find a variety of applications such as ultra-wide-band phase shifters, high-speed microelectronic interconnections, pulse shaping, delay control, dispersion compensations, and wave-packet switching, for instance. This paper reports for the first time negative group velocities in a lumped C-L line, where capacitors C and inductors L connected to resistors are placed, respectively, in the series and shunt branches of the periodic line. The NGD effects are induced by ohmic dissipation due to the resistors which establish a frequency range in which NGD propagation is allowed. This finding is numerically demonstrated by injecting into the line a 180 kHz modulated Gaussian pulse, with a full width at half maximum of 22.20 µs, for which the negative time delay of -1.26 µs determined from the numerical solution of circuit equations is in good agreement with that predicted by the analytical dispersion relation of the periodic structure.
In this paper we present an analysis of the properties and applicability of the complementary frequency selective surfaces (CFSS), which have multiband behavior and great angular stability as main characteristics. Computational simulations are done by proposing a new design CFSS for satellite communication with dual-passband response and angular stability considering a wide range of angles of incidence. Parametric analyzes and discussion of results finalize this study.
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 radomes and electromagnetic wave absorbers. This work aims to study the use of FSS to design microwave absorbers. For the analysis the ANSYS HFSS software will be used, which provides transmission characteristics of the structure for a flat wave. Initial results will be presented, demonstrating the understanding of the effects analyzed.
This contribution will demonstrate that the use of Laplace transform allows for analyzing the reflected distorted thin pulse stemming from a dissipative dielectric interface. Its energy evaluation allows the synthesis of a perfect effective pulse that can be applied directly to TLM-SCN (Transmission Line Modelling — Symmetrical Condensed Node) time domain algorithm. This prevents the use of Green's function approach that usually requires a large amount of memory. The theory is validated by applying it to the analysis of a transmission line terminating in another infinite line filled with dissipative dielectric. The resulting standing wave provides the signal response behavior in the time domain. The results will compare with those obtained from harmonic analysis.
In this paper, we present the design, fabrication and calibration of a passive UHF RFID tag based soil moisture and environment temperature sensor. The inter-digital double-sided capacitive sensor developed modifies its capacitance as the soil moisture changes, due to modification of the soil permittivity. The implemented smart tag includes an external sensor front-end that is capable to process analog sensors and send digitized measurements to the reader. In order to obtain reliable readings, a process of calibration was performed and described. The used RFID chip also includes a built-in temperature sensor. The developed sensor tag presented a 6.95 ADC LSB variation per soil water content percentage and the capability to measure temperatures in a range of 0.3-59.6 ºC with a 0.058ºC resolution.
In this work we present the performance of metallic (copper and aluminum) and graphene buckypaper based microstrip transmission lines and the comparison between these device configurations. The graphene buckypapers were deposited by a simple vacuum filtration method, leading to freestanding paper with 350 um thickness and diameter up to 1.2 inches. After deposition and drying, the graphene paper and the metallic bands were strips cut by UV laser. The transmission line strips were fixed over alumina substrates with gold backside metallic ground. The S-parameter of these graphene microstrips allows to know the conductivity behavior of carbon electronics when compared with copper and aluminum transmission lines over a wide band of frequencies (from 0.5 to 10 GHz).
This paper proposes the use of frequency selective surfaces as electromagnetic shielding on 5G communication devices. This technique intends to enhance the susceptibility from external radiated fields while decreases the radiation emissions in out of communication band, improving the overall electromagnetic compatibility performance of the device. Besides the shielding effect, the frequency selective surface structure should have minimal interference on 5G communication. In order to address this concern, the effects of the FSS shielding in a 28GHz 5x5 patch antenna array installed on a generic smart phone was investigated. Numerical results shows that this technique blocks electromagnetic fields generated at lower frequencies as intended, such as those produced by a DDR4 system operating at 3.2GHz, while decreasing the main lobe of the antenna array in less than 0.9dB for a theta scan angle ranging from 0 to 30 deg.
In this paper, we present a radio frequency (RF) transmitter front-end that can be used in analog beamforming applications with achieved gain of 11.1dB. The proposed system is modular and can be used in different frequency bands. Using low-cost components and substrates, this design makes analog beamforming affordable also for commercial applications. We demonstrate the system performance in terms of S-parameters and measurements with frequency translation to C-band. Reproducibility of the achieved results is shown by analyzing multiple front-end prototypes.
Gyromagnetic nonlinear transmission lines are interesting new devices used for RF generation since they are all solid state, lightweight and compact, neither requiring vacuum nor thermionic filament as in electronic tubes. Experiments with these lines have demonstrated their successful operation at L and S bands, thereby enabling them for applications in UWB pulsed radars in space vehicles and defense systems. There is also a great interest in compact solid-state high power microwave sources for applications in small defense platforms (boats, trucks, etc.) to destroy the enemy electronic systems. Although the operation of these devices has been demonstrated exhaustively in recent years, their working principle is not quite well understood so far as it has been expected that the precession of the magnetic dipoles in the ferrite material given by the Larmor frequency, which predicts a proportional increase with the magnetic field bias. However, as observed experimentally the opposite occurs and the frequency decreases with the increasing of the magnetic field applied. Thus, the objective of this paper is to address this problem using the Landau-Lifshitz-Gilbert (LLG) equation with boundary conditions on the TEM mode propagation in the coaxial line. The formulation obtained for the precession frequency will be used to compare with experimental data found in the literature.
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 along a microstrip conductor made out of palladium.
This paper presents a simple, compact, and reconfigurable patch element geometry for multiband FSS applications. The patch element reconfigurability enables the development of reconfigurable FSS structures. The proposed FSS reconfigurability is theoretically and experimentally investigated through the use of small thin conducting strips on the FSS patch element geometry. Simulation is performed using Ansoft HFSS software. It is shown that the proposed FSS structure in different configurations can be used to cover a wide frequency range, with very good angular stability (with respect to the oblique incidence of plane waves), being suitable for wireless communication applications and cognitive radio. Simulation and measurements results are compared and a good agreement is verified.
This work presents the design of a compact antenna using microstrip patch based on a fractal model for use in Internet-of-Things (IoT) wireless communication in sub-GHz bands. The proposed antenna was implemented on a low cost FR-4 substrate and work in the 433 MHz and 915 MHz or 868 MHz frequencies that are ISM bands used in the IoT networks. The suggested antenna has been manufactured and experimentally characterized, showing a good agreement with the expected simulated results.
This paper presents a microstrip antenna with controlled gain and directivity. The gain control of antenna is achieved by employing a Reconfigurable Frequency Selective Surface (RFSS) as superstrate which is formed by 2 x 2 array of square loops. The RFSS resonance is variable and depends on the PIN diodes biasing. When all diodes are in the ON-state, the RFSS resonates at 1.89 GHz, and at 3.00 GHz when the diodes are in the OFF-state. The RFSS resonance influences the antenna behavior which operates at 2.40 GHz. Analyses of the simulated antenna gain, radiation pattern and return loss are shown. The gain improvement depends on the PIN diodes biasing. The improvement is 2.95 dB and reduction is 6.95 dB at 2.40 GHz for reverse and forward bias, respectively. At reverse bias, the main lobe is in the opposite direction comparing to the forward bias.
This paper proposes a new feeding scheme for exciting a higher-order resonant mode in cylindrical dielectric resonator antennas. The proposed feeding structure comprises a non-resonant microstrip patch connected to a narrow microstrip line by means of an inset. Both the microstrip patch and line are located under the antenna radiating element (dielectric resonator). A parametric analysis of this feeding structure has been carried out using electromagnetic simulation. The results of this analysis indicate that the antenna impedance matching can be adjusted by changing the length of the inset, and that different values of directivity and impedance bandwidth can be obtained by using different microstrip patch sizes and inset lengths. An antenna prototype has been designed and fabricated to validate the proposed feeding structure using a dielectric resonator with a high dielectric constant. The measured resonance frequency and impedance bandwidth of this prototype are 6.20 GHz and 25.0 MHz (fractional bandwidth of 0.403%), respectively, showing good agreement between simulated and experimental results.
The constant technological innovation in the telecommunications area means that more and more people are exposed to electromagnetic radiation from a variety of sources. The concern with the possible health risks that this exposure can cause in the population motivates many organizations to develop studies with the aim to establish limits of human exposure to this type of radiation. The knowledge of these exposure limits and how these fields are spatially distributed are very important to the development of techniques to protect against this kind of radiation. The aim of this paper is to study the distribution of the electromagnetic pollution in the central region of Mossoro by measuring the intensity of the electromagnetic fields in a broad band from 10 MHz to 8 GHz and estimate how these fields are spatially distributed using interpolations techniques.
A graphene antenna that exhibits a controllable radiation pattern is proposed. The antenna is formed by a graphene dipole and two parasitic elements, and operates at 1.84 THz. At this frequency, it is possible select three operation states by choosing the values of chemicals potentials applied on the graphene parasitic elements. In two of these states, due to the obtained current antiphase modes, the proposed antenna presents a directional lobe, which can be directed to -x-direction or x-direction depending on the device operation state.The third state consists in a dipole-like radiation pattern.
This paper aims to present the influence of a metasurface, a special type of metamaterials, in the performace of a microstrip antenna. We design and manufacture a microstrip antenna with and without the use of a metasurface. Simulations were done with ANSYS software and measurements were realized with a E5071C ENA Network Analyzer. A comparative analysis, showing how the metasurface changes the performance of a microstrip, is done.
This paper presents an analysis of four impedance matching techniques to apply in tapered microstrip patch antenna fed by microstrip-line. The techniques used are inset-feed, quarter-wave transformer, displaced-line, and hybrid-line, which is a combination of the other three techniques. The antennas were designed to an operation frequency of 5 GHz. Antenna analysis and measurement were done using commercial software Ansys DesignerTM and Agilent vector network analyzer, respectively. From obtained results we observe antenna bandwidth improvement considering each microstrip-line feeding technique used for antenna impedance matching. Tapered antenna using the hybrid-line feeding technique achieved a 430 MHz (8.28%) measured bandwidth, corresponding to an increase of 391% in relation to the inset-fed tapered antenna 110 MHz (2.20%) bandwidth. Simulated and measured results are presented, being observed a good agreement between them.
The main goal of this work is to find the required parameters for the construction of microstrip antennas, which have rectangular and circular patch. For this, an optimization technique is used, the Taguchi Method, where each parameter is defined from the desired resonance frequency, from the electrical characteristics of the material that will be used to fabricated the antenna (thickness and dielectric constant of the substrate) and the definition of maximum and minimum values that the parameters can achieve. Numerical and experimental results are presented for validation purpose of the technique.
This paper presents an antenna miniaturization technique which consists in using the space-filling property offered by the fractal concept. A rectangular Koch curve is applied in a dual-band H-shaped patch radiator in order to miniaturize the antenna at each level of iteration. The approach is validated by simulated and experimental results which demonstrate good agreement. In comparison with the conventional H-shaped antenna, the H-shaped fractal antennas of level 1 and 2 present a lower first resonant frequency. This technique achieves miniaturization of up to 30 percent of the antenna's total size.
This paper presents rectangular Koch pre-fractal patch antenna until three iterations on wearable flexible polyamide dielectric operating in ultrahigh frequency band. The antennas were implemented by MATLAB, exported in DXF format and simulated in commercial software ANSYS. The polyamide presents characteristics of mechanical and thermal resistance suitable for wearable applications that require high temperature resistance and constant movement. The use of Koch pre-fractal geometries from square patch antenna provides a decrease of 20.3 % in resonance frequency, and 30º in half power beamwidth, making it more directional (first iteration). The wearable patch antenna with Koch pre-fractal for the third iteration shows maximum gain at the resonance frequency of 5.57 dBi, and current density of 41 A/m2.
Optical Poster — 02 / Wednesday, August 30th / 11:20—13:00 / Esmeralda Room
This paper presents few developments on CMOS microelectronics for the implementation of photonic modules on endoscopic capsules (ECs). The first microelectronic system was developed with the goal to allow photodynamic therapy (PDT) on ECs. This first system was designed in the 2 metals/1 poly 0.7um CMOS process from the on semiconductor. The second development is an optical sensor designed for spectroscopy analysis on ECs from diffuse reflectance light originated in the gastrointestinal tissue. This second system was designed in the mixed-signal/RF 0.18um CMOS general process from the Taiwan Semiconductor (TSMC).
This work presents the application studies of holographic techniques using LCoS-SLM (Liquid Crystal on Silicon — Spatial Light Modulators) to replace the masks in photolithography process. Computer-generated holograms obtained from two images with known dimensions, simulating a Clear Field Mask and a Dark Field Mask, were applied to one LCoS-SLM connected to an holographic optical setup capable of reducing the reconstructed images, allowing the survey of the most relevant parameters of the photolithography process for the manufacture of fine structures and from their characterization identify the limits imposed by LCoS-SLM in the process. The results are good and presents excellent possibilities of a holographic system applied to processes of Maskless Photolithography.
In this work Interpolating Element-Free Galerkin Method (IEFGM) is presented as simple and accurate technique to investigate grounding problems. However, as IEFGM is a differential equation method, it is necessary to stablish a boundary in order to define the computational domain of the problem and where a specific boundary condition should be imposed. Thus, a new methodology which reduces the computational domain for analysis of steady state ground problems is proposed. To prove the efficiency of the method a study case of a vertical electrode introduced in a homogeneous soil is presented. The results of IEFGM were compared with Method of Moments results.
A self-calibration noniterative technique for determination of the optical constants and thickness of lossless materials using only three reflection measurements is proposed. A generalized model is derived based on the reflection measurements. For validation, two different samples (Si and GaAs samples) are considered for extraction of their optical parameters and thicknesses by using a numerical full wave electromagnetic simulator. It is demonstrated that the proposed method can retrieve highly accurate results provided that reflected signal components are accurately separated.
We present an analysis of the optical detection of two-dimensional vibration waves from two interferometric systems: a point-scanning heterodyne interferometer by optical reinjection (Laser Optical Feedback Imaging — LOFI) and a full-field stroboscopic Mach-Zehnder interferometer. We compare the spatial (resolution, sensitivity) and temporal (resolution, speed, bandwidth) performances for both vibrometers and discuss their application to photoacoustic imaging.
This paper presents the implementation of an OFDM Radio over Fiber System at 2.5 GHz using Software Defined Radio SDR. In this work first, we present an introduction of the main concepts about Radio over Fiber and an Orthogonal Frequency-Division Multiplexing OFDM System at 2.5 GHz, then we present a comparison of an OFDM RoF system in three scenarios, modifying the wireless distances and the optical fiber distance in order to evaluate the performance of the system taking into account the SER vs SNR curves.
Optical fiber sensors have become a popular alternative to traditional electronic sensors due to their numerous advantages. An important challenge in deploying optical sensors is the interrogation of the sensor, that is, recovering the measured value from the sensor output. This paper aims to present a simple yet effective way of interrogating a fiber Bragg grating (FBG) temperature sensor using optical filters and an artificial neural network (ANN). This interrogation system is capable of giving the precise temperature value without directly measuring the resonance wavelength shift or performing any Fourier calculations. The network was implemented and the training was accomplished using simulated data. Simulated results are presented and compared to traditional methods of interrogation. The system proposed in this paper showed excellent performance in identifying the temperature from the sensor output and showed more precision than the traditional method.
In this work, we carry out theoretically the mode analysis of a D-shaped porous fiber with a thin gold layer in the THz spectral range. From a proper design of the gold layer, effective losses can be reduced and a zero waveguide dispersion is achieved as the result of the coupling between the fiber modes and surface plasmons. We argue that the reached guidance features can be used to implement in the THz spectrum an analog version of SPR (surface plasmon resonance) D-type optical fibers.
The work presents a new proposition of an integrated optical device applicable as optical magnetometer. The studies of an optical waveguide formed by thermally induced static stress (ISS) and modulation achieved by magnetostriction of a TbCo2 thin film over Bismuth Germanate (BGO) are shown. The magnetooptical effect and the modal optical analyses were investigated for the optical modulation purpose. The analyses were performed by a finite element method (FEM) based software. The optical propagation characteristics of the magnetooptically disturbed guided modes in stress-induced waveguides were evaluated indicating the viability of proposed device application as magnetometer.
In this work we propose and numerically analyze new type of electromagnetic circulator based solely on graphene and dielectric substrates operating THz range. The structure resembles a known three-port microstrip circulator based in edge guided mode propagation. A edge guided plasmonic wave is injected and the circulation behavior is obtained by the application of magnetostatic field in the structure and its characteristics can be dynamically controlled by electrostatic external fields. The Transmission level are better than -2.85 dB and isolation is -37.4 dB in a frequency of 5.32 THz.
In this paper the vibration analysis of a cantilever beam with viscoelastic neutralizer using fiber Bragg gratings (FBG) is presented. The optimal design, of the neutralizer, is achieved through a robust methodology developed by the Research Group on Vibrations and Sound in Mechanical Systems (GVIBS) at Federal University of Paraná (UFPR). Such methodology uses the Finite Element Method (FEM) to obtain the modal analysis of the system that will be controlled. The Generalized Equivalent Parameters (GEP) and Nonlinear Optimization Techniques (NLOT) are applied. The viscoelastic neutralizer was projected to control the range of frequency 250 Hz to 470 Hz. To verify the efficiency of the neutralizer the response of the FBG was compared with the response of the piezoelectric accelerometer. Both systems were positioned close to the clamped part of the beam. The analysis presents the efficiency of the viscoelastic neutralizer, proven by decrease of amplitude for the analyzed range when using the optical technique (25 dB) and traditional sensor (32 dB). This study allows validating the effectiveness of the vibration measurements of the FBG to the viscoelastic neutralizers projects.
This work describes a study about encapsulation of fiber Bragg gratings in elastomer materials for sensing purposes. Sensors were tested in measurements of forces resulting from loads applied to the sensor within a measuring interval from 0 to 1500 grams. It was analyzed the influence of the elastomer composition in the sensor response. Results point to the possibility of adjusting the responses in order to adequate the sensors for specific applications. Metrological characteristics were evaluated regarding the sensors sensitivity, linearity, hysteresis and resolution. The silicone elastomer DOW CORNING® BX3-8001 stood out due to the possibility of changing its hardness and also due to the lower cure time, resulting in a sensor with sensitivity of (0.312 ± 0.002) pm/g, resolution of (1.6 ± 0.6) g, linearity of ± 4.19 % and hysteresis of ± 6.29 %.
We present the first phase-shifted polymer optical fiber Bragg grating sensor inscribed with only one KrF laser pulse. The phase shift defect was created directly during the grating inscription process by placing a very narrow blocking aperture, in the center of the UV beam. One laser pulse with a duration of 15 ns and energy 6.3 mJ is adequate to introduce a refractive index change of 0.69×10-4 in the fiber core. The high-quality produced Bragg grating structure rejects 16.3 dB transmitted power, thus providing 97.6% reflectivity, which is well suited for photonic applications. The transmission notch depth is about 10 dB and very sharp notches of 3 dB width ranging from 14 pm is reported. The temperature, strain, and pressure response of the sensor has been characterized showing promising results in applications that require high-precision measurements. The ability to inscribe these high-quality sensors effectively can significantly reduce their production cost in industry.
In this work we propose a new electronic method for fiber Bragg grating (FBG) temperature compensation. This method uses a voltage-controlled gain amplifier (VGA) to compensation of temperature effects in a FBG sensing system that uses the edge filtering technique in the sensor's interrogator. We describe the technique and it application in a FBG vibration monitoring system.
In this work it is presented a model based on the beam propagation method able to enhance sensing structures constructed with tapered single mode fibers associated with bending monitored in the transmitted power condition. It is made comparisons among the numerical results of the model and the experimental ones and it is demonstrated good agreement with them. Thus, the model is proven to be suitable to simulate new parameters of the device in order to obtain better performance. It is demonstrated by numerical simulations that it is possible to enhance the sensor response through varying simultaneously the length and waist of the taper. It is shown that it is possible to obtain a sensitivity of about 0.7 dB/degree using a taper length of 1200 micrometers and waist of 30 micrometers at an angular range of 35 to 45 degrees.
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 a bulk fill composite of low viscosity inside a teeth cavity, prepared to replace teeth tissue lost by caries and fractures. Fiber Bragg grating sensors are used in this investigation due their great sensibility and small dimensions. The results reveal shrinkage polymerization of -863±168 µε and temperature change of 12±7°C. The temperature variationis high and can compromise the pulp vitality.
This paper is regarding a GPON-based front-end for multiband 5G cellular networks operating at microwave and mm-waves frequencies. We propose to use an existing optics-fiber infrastructure as a front-end for future optical-wireless 5G networks, by means of applying gigabit-capable passive optical and radio over fiber technologies. Numerical simulations demonstrate the viability of providing 1 and 10 Gbps using 6 and 38 GHz frequency bands, respectively, which have been considered potential for 5G systems. A performance analysis has been carried out as a function of 64-QAM constellations, signal-to-noise ratio (SNR) and bit error rate (BER). The applicability of the proposed architecture is illustrated by simultaneously transmitting a baseband signal at 2.5 Gbps with BER as low as 10-10 and two different 5G signals at 6 and 38 GHz with SNR higher than 38 dB and BER of 10-3.
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 to achievable error-free transmission. Here, we perform an experimental comparison of two different linearization schemes for electro-optical conversion to be employed in a-RoF. Both techniques can lower third order intermodulation products by 12 dB, a result that enhances the error-free range of a-RoF transmission by a factor of six.
A first theoretical and numerical treatment of longitudinal forces in an extended geometrical optics model exerted by a truncated Bessel beam (TBB) on a spherical dielectric particle is presented in this work. To describe the TBB, we use a method for spatial beam shaping to describe truncated beams with simplicity and total analyticity in the paraxial approximation, which utilizes a discrete superposition of scalar Bessel Gauss beams. We present numerical examples of longitudinal forces that a TBB exerts on a scatterer and argue about the limitations of this method. We also briefly discuss about further possible analysis that can be done with TBB and others truncated beams.
In this work we report the development of a method to characterize occlusal splints using fiber Bragg grating sensors. The occlusal splints are used to treatment for muscle pain resulting from parafunctional habit and or occlusal alterations. The gratings are inserted in to the occlusal splints in order to measure the forces applied to the splints. The analyses are performed in a volunteer with bruxism, in order to obtain the sensibility to the applied load. The analyses of the force distribution in the splint are realized in vivo and the results indicate that the proposed method is a powerful tool for the characterization of occlusal splints.
RF Poster — 02 / Wednesday, August 30th / 11:20—13:00 / Esmeralda Room
As a consequence of their large size and surface geometry, military transport helicopters have usually large radar cross sections (RCS). Depending on the type of the mission these helicopters are carrying, it would be advantageous for the helicopter lo have a smaller RCS. The RCS of any target can be minimized using different methods. In this study, the RCS of a helicopter was simulated assuming that it was covered by a multifunctional composite that can function both as structural material and narrow band microwave absorber. Simulations were performed ad 8 and 12 GHz and the results indicate that a considerable reduction of the overall RCS of the helicopter at 12 GHz can be obtained using the multifunctional composite.
A new planar sensor based on the matryoshka microstrip resonator is presented in this paper. The matryoshka resonator is described and its properties discussed, including initial project equations to calculate the first resonant frequencies. The sensor was fabricated and successfully applied to distinguish three different liquids (water, alcohol 46º INPM and acetone). Furthermore, the proposed sensor is employed to identify different concentrations of alcohol. The achieved results make the new planar sensor potentially attractive to many applications, motivating the investigation of its properties.
This paper compares empirical chemical kinetic equations for salicylic acid acylation obtained under 2.45 GHz electromagnetic radiation with conventional electric heating. Results show changes in the activation energy value and in reactions orders, which indicate an alteration of the reaction mechanism. This mechanism alteration is accepted as the cause for microwave enhancement of this reaction. A new concept of microwave irradiated chemical reactor used in these experiments is described.
This paper presents in-situ evaluations comparing the EMF exposure associated with a BTS installed in the vicinity of an apartment, WLAN device and baby monitor in a typical scenario. The results show that under certain circumstances the exposure in the latter cases can be higher than the former.
The present work is a first attempt to introduce physical or finite energy axially symmetric fields, under the paraxial approximation, into the theoretical framework of the generalized Lorenz-Mie theory. Based on analytical descriptions in terms of a discrete superposition of Bessel-Gauss beams, we derive the beam shape coefficients of a particular class of axially symmetric beams, viz. truncated zero-order scalar Bessel beams. The analyticity of the present approach is interesting from the perspective that it avoids, from the very outset, extensive computational optimization processes involved in ABCD optical systems or the introduction of non-physical ideal (infinite energy) solutions of Maxwell's equations. As an example of application, optical forces exerted on spherical nano and microparticles are calculated and compared with those forces as evaluated with ideal scalar Bessel beams. Since it can be readily extended so as to encompass other types of axially symmetric truncated beams, we envision the present approach as a fast computational technique for immediate implementation in the analysis of light scattering by nano- and micro-particles.
This paper aims to investigate one of the most important schemes, viz. the localized approximation (LA), for describing arbitrary-shaped beams in the generalized Lorenz-Mie theory. Our focus is on a specific class of non-diffracting beams called discrete frozen waves, which are constructed from superpositions of Bessel beams and can be designed to provide virtually any longitudinal intensity pattern of interest. Recently, the LA was applied to frozen waves allowing, for the first time, for the analysis of light scattering problems from spherical scatterers and the subsequent determination of the physical/optical quantities in optical trapping. Since the LA cannot be rigorously applied to Bessel beams, it is of interest to determine whether those results and predictions previously established in the literature are reliable or not. To do so, we rely on exact descriptions of frozen waves and establish the limits to the validity of such an approximation scheme. It is revealed that, although serious doubts can be raised against its use, specially due to cumulative errors, the LA is much more robust than previously thought, and it may serve well to both paraxial and non-paraxial Frozen Waves, under certain circumstances.
This paper aims to achieve analytical descriptions of specific classes of finite-energy non-diffracting beams, viz. the so-called Frozen Waves, envisioning applications in optical trapping. Such solutions to the Fresnel diffraction integral can be constructed from specific discrete superpositions of finite-energy zero-order scalar Bessel-Gauss beams. Here, we present expressions for their beam shape coefficients in the context of the generalized Lorenz-Mie theory. The paraxial regime is valid for all Bessel-Gauss beams, thus allowing the method here presented to be purely analytic. The analyticity avoids both extensive numerical computation and optimization schemes. Radiation pressure cross sections, which are proportional to optical forces, are then evaluated for Rayleigh particles as an example of application. We expect Frozen Waves to serve, in the near future, as alternative laser beams in biomedical optics and in the optical micromanipulation of biological or auxiliary particles.
The attenuation due to rain is the main source of impairments in satellite links operating above 10 GHz. In the design of systems based on Low Earth Orbit (LEO) satellites, the analysis of the rain attenuation must take into account both azimuth and elevation variations. It requires a deep knowledge on the nature of this dependence. As measurements at several elevation and azimuth angles are not available, it is necessary to use prediction models that aim at reproducing the rain profiles of each link. This paper presents an analysis of the azimuth dependence of rain attenuation according to the size of the azimuthal window where this attenuation occurs. It is shown that the azimuthal rain attenuation windows smaller than 180° are few at higher elevation but their probability increases exponentially with the decreasing of the elevation.
Hybrid precoding, which refers to the combined use of phased arrays and digital (baseband) beamforming, is the main transceiver architecture under consideration for millimeterwave (mmWave) wireless systems. However, this configuration is not suitable for receivers with a single RF chain, that must rely on fully-analog beamforming. In this paper, we consider the problem of finding the best analog beam combination when user terminals have independent analog sub-arrays. We present a novel algorithm for beam selection that separates analog and digital beamforming components. First, we use hierarchical analog beamforming codebooks to obtain a combination of beamformers that maximize SNR at the receivers. We leverage multiple RF chains at the AP and sub-arrays at the users to design such hierarchical codebooks. Second, we use digital zero-forcing beamforming at the transmitter to eliminate inter-user interference. Preliminary numerical results show the effectiveness of our algorithm in simple scenarios.
Passive radar applications are already cleared up by Software-Defined Radio (SDR) technology. Nevertheless, until now, no work has deliberated how this flexible radio could fully and directly exploit pulsed radar signals. This paper aims at introducing this field of study presenting not only an SDR-based radar-detector but also how it could be conceived on a low energy consumption device, which would make convenient a passive network to identify and localize aircraft as a redundancy in adverse situations of the conventional air traffic control. After a brief approach of the main features of the equipment, as well as of the developed processing script, indoor experiments took place. Their results demonstrate that the processing of pulsed radar signal allows emitters to be identified when a local database is confronted using only an SDR dongle and a tablet device. All this commitment has contributed to a greater proposal of an Electronic Intelligence (ELINT) or Electronic Support Measures (ESM) system embedded on a tablet, presenting characteristics of portability, furtiveness and, the best of them, no subjection to arms embargoes. This study is suggested for the areas of Electronic Warfare, Electromagnetic Devices, Radar Signal Processing and Software-Defined Radio.
Power amplifier (PA) behaviour modelling is a crucial technique for the improvement of telecommunication systems because it constitutes the core of a linearisation circuit that allows for the amplifier to develop high efficiencies at the same time that it delivers a linear output signal to the load. Polynomial filters can be used in order to represent both the non-linearities of the PA and the memory effects caused by passive elements of the circuit. This work proposes a different structure for a PA polynomial behaviour model, using finite impulse response (FIR) filters and one-dimensional polynomials. The memory polynomial (MP) and the envelope memory polynomial (EMP) models were used not only as a foundation for the proposed model but also as references points for performance validation. All models were applied to a class AB GaN PA driven by a WCDMA envelope signal. Results shown an enhancement on performance for the proposed model when its accuracy was compared with the one obtained by the MP and EMP models. In contrast with the first one, the proposed model had an improvement of 4.1 dB in its normalized mean square error (NMSE), with the second one, the improvement was of 5.9 dB.
In this paper we obtain a Maximum Likelihood Estimator (MLE) for average received power in a multiuser non coherent MFSK system over a fast Rayleigh fading channel. It is shown that this estimator is unbiased and that its variance can be obtained by a simple linear function. The Cramer Rao lower bound (CRLB) is derived and compared to the MLE's variance. It is shown that only in most of the practical cases the MLE is inefficient by a multiplier that depends on system parameters but not on the number of sample points used. Numerical results are obtained and average performance is analyzed.
This paper presents the design of a patch antenna with structure bio-inspired by the Wayfaring-tree (Viburnum lantana) leaf chosen from the European native flora, for applications in wireless communication systems. The antenna was manufactured in low-cost FR-4 fiberglass substrate, fed by a microstrip line using the hybrid technique with matching impedances of 50Ω. Specifically the antenna is designed for operation in the 2400-2483.5 MHz range of the IEEE802.11b, g, n (Wi-Fi) and IEEE802.15 (Bluetooth). Ansys Designer® simulator software was used for numerical characterization and a vector network analyzer for the experimental characterization. The proposed antenna presents a bandwidth of 61 MHz, measured return loss of 37.14 dB at 2.44 GHz, and maximum gain of 6.5 dBi in the broadside direction.
This paper presents an analysis of a dual-band array for base stations of mobile communication systems. The main challenge is to suppress grating lobes for interelement spacings equal or larger than the wavelength. In order to achieve this result, particle swarm optimization (PSO) is used to find the optimum excitation coefficients (amplitudes and phases) and the non-uniform spacing between elements of the array. The suppression of grating lobes is shown by comparisons with results obtained by a standard uniform linear array for two cases: standard beam pointing to the boresight, and main beam with squared cosecant shape. The use of non-uniform spaced arrays allowed reducing grating lobes in comparison to a standard uniform array.
The goal of this paper is to predict the propagation loss of 4G signals by means of a static empirical approach, which lists the data obtained through a measurement campaign conducted at Castanhal City, located in the state of Pará (northern Brazil), which it was obtained through the power of the LTE signal transmitted at a frequency of 1.8 GHz. With the use of computational intelligence Artificial Neural Networks (ANN) and Neuro-Fuzzy System (NFS) techniques. The input parameters was distance between Tx and Rx, height and gain of the transmitting antenna in order to predict the path loss on a specific point. And thus to compare the Root Mean Square Error (RMSE) rate obtained with some existing classical path loss models in the literature: Cost 231-Hata, Ikegami-Walfisch and ITU-R P.1546-4.
This paper proposes a method for suppression of higher order harmonics in microstrip antenna using spur-line filter. The microstrip antenna is designed to operate at a frequency 2.45 GHz. In antenna design was used the combination of the quarter-wave transformer and inset feed impedance matching techniques. The spur-line filter was inserted in the antenna microstrip feed line being designed to suppress the second and third harmonics. The measured and simulated results are presented for the proposed antenna. From a comparative analysis of the antenna radiation properties is shown that the insertion of spur-line filter does not degradate the radiation pattern.
This paper presents a FDTD CUDA based implementation designed for microstrip antennas simulation. Aspects of geometry and also memory transactions are considered in the formulation of the parallel algorithm. As a result, an improvement in computational cost is achieved using the implementation proposed. Two microstrip antennas, a narrow band patch antenna and a UWB antenna, are simulated to validate the proposed algorithm.
Design of microstrip antenna arrays using dissimilar circular patch elements is presented in this paper to cover the band 2.400-2.483 GHz required in IEEE802.11b,g applications. The following antenna prototypes were designed and built: circular patch antenna, 1x2 and 1x4 arrays. Proposed arrays presented an impedance bandwidth above to 100 MHz and 1x4 array synthetizes a broadside radiation pattern with gain more than 8 dBi and front-to-back ratio greater than 20 dB.
Accurate parametric models capable of describing the electrical characteristics of short twisted-pair cables operating at relatively high frequencies are key elements for design the next generation broadband over copper. In this paper we present an experimental procedure for refining the parameters of a well-known 1% worst-case crosstalk model in order to better characterize these new transmission scenarios.
The present paper reports on the radiation properties of a horn antenna covered with a wire medium structure. This approach is an innovative application for the wire medium and horn antenna where the artificial structure changes the radiation patterns of the uncovered horn antenna, for which some strong effects are observed. The design and constructive details are presented together with full-wave electromagnetic simulations and experiments. Structural design and analysis are in the X band frequency range (8.2 to 12.4 GHz) whereby numerical simulation and experiment are presented and discussed along with wire medium electromagnetic theory.
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. Using a EMF low frequency spectrum analyzer with high sensitivity (1 µV) operating in the range of 1-12 Hz and using a low sampling time (5 ms), it was possible to measure HF waves. A series of measurements were carried out in São José dos Campos, Brazil, from September, 2016 to March, 2017 diamagnetic currents under dry conditions and with the analyzer isolated from electrical discharges to detect and record these waves. The positive results of the experimental observations suggest a possible confirmation of the occurrence of diamagnetic currents in ionosphere.
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.