{"title":"Realization of All-Optical Digital Amplification in Coupled Nonlinear Photonic Crystal Waveguides","authors":"V. Jandieri, R. Khomeriki, D. Erni, W. Chew","doi":"10.2528/PIER17010704","DOIUrl":"https://doi.org/10.2528/PIER17010704","url":null,"abstract":"In this conceptual study, all-optical amplification of the light pulses in two weakly coupled nonlinear photonic crystal waveguides (PCWs) is proposed. We consider two adjacent PCWs, which consist of line defects in a 2D square lattice of periodically distributed circular rods made from dielectric material with Kerr-type nonlinearity. Dispersion diagrams of the PCW’s symmetric and antisymmetric modes are analyzed using a recently developed analytical formulation. The operating frequency is properly chosen to be located at the edge of the PCW’s dispersion diagram (i.e., adjacent to the photonic crystals low-energy band edge), where in the linear case no propagation modes are excited. However, in case of a nonlinear medium when the amplitude of the injected signal is above some threshold value, solitons are formed propagating inside the coupled nonlinear PCWs. The near field distributions of the propagating light pulse inside the coupled nonlinear PCWs and the output power of the received signal are numerically studied in a detail. A very good agreement between the analytic soliton solution based on the nonlinear Schrödinger equation and numerical result is obtained. Amplification coefficients are calculated for the various amplitudes of the input signals. The results vividly demonstrate the effectiveness of the weakly coupled nonlinear PCWs as an all-optical digital amplifier.","PeriodicalId":54551,"journal":{"name":"Progress in Electromagnetics Research-Pier","volume":"64 1","pages":"63-72"},"PeriodicalIF":6.7,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75297736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. He, Chuan Lu, N. Chen, D. Lin, M. Rosu, P. Zhou
{"title":"Time Decomposition Method for the General Transient Simulation of Low-Frequency Electromagnetics","authors":"B. He, Chuan Lu, N. Chen, D. Lin, M. Rosu, P. Zhou","doi":"10.2528/PIER17072501","DOIUrl":"https://doi.org/10.2528/PIER17072501","url":null,"abstract":"This paper describes a highly robust and efficient parallel computing method for the transient simulation of low-frequency electromagnetics with nonlinear materials and/or permanent magnets. In this method, time subdivisions are introduced to control the memory usage and nonlinear convergence. A direct block triangular matrix solver is applied to solve the formulated block matrix for each subdivision. This method has been implemented using the Message Passing Interface (MPI) for distributed memory parallel processing. Depending on the number of available MPI processes and physical memory, the entire nonlinear transient simulation can be divided into several subdivisions along the time-axis such that each MPI process handles only the computation for one time-step. Application examples are presented to demonstrate that this method can achieve excellent scalability of speedup.","PeriodicalId":54551,"journal":{"name":"Progress in Electromagnetics Research-Pier","volume":"2 1","pages":"1-8"},"PeriodicalIF":6.7,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78950546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Syms, E. Kardoulaki, M. Rea, K. Choonee, S. Taylor-Robinson, C. Wadsworth, I. Young
{"title":"Magneto-Inductive Magnetic Resonance Imaging Duodenoscope","authors":"R. Syms, E. Kardoulaki, M. Rea, K. Choonee, S. Taylor-Robinson, C. Wadsworth, I. Young","doi":"10.2528/PIER17062104","DOIUrl":"https://doi.org/10.2528/PIER17062104","url":null,"abstract":"A magnetic resonance imaging (MRI) duodenoscope is demonstrated, by combining non magnetic endoscope components with a thin - film receiver based on a magneto - inductive waveguide. The waveguide elements consist of figure - of - eight shaped inductors formed on either side of a flexible substrate and parallel plate capacitors that use the substrate as a dielectric. Operation is simulated using equivalent circuit models and by computation of two and three - dimensional sensitivity patterns. Circuits are fabricated for operation at 127.7 MHz by double - sided patterning of copper - clad Kapton and assembled on to non - magnetic flexible endoscope insertion tubes. Operation is verified by bench testing and by 1 H MRI at 3T using phantoms. The receiver can form a segmented coaxial image along the length of the endoscope, even when bent, and shows a signal - to - noise - ra tio advantage over a surface array coil up to three times the tube diameter at the tip. Initial immersion imaging experiments have been carried out and confirm an encouraging lack of sensitivity to RF heating.","PeriodicalId":54551,"journal":{"name":"Progress in Electromagnetics Research-Pier","volume":"24 1","pages":"125-138"},"PeriodicalIF":6.7,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88060065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. R. Prado, Á. F. Vaquero, M. Arrebola, M. Pino, F. Las-Heras
{"title":"GENERAL NEAR FIELD SYNTHESIS OF REFLECTARRAY ANTENNAS FOR THEIR USE AS PROBES IN CATR","authors":"D. R. Prado, Á. F. Vaquero, M. Arrebola, M. Pino, F. Las-Heras","doi":"10.2528/PIER17072705","DOIUrl":"https://doi.org/10.2528/PIER17072705","url":null,"abstract":"In this work, reflectarray antennas are proposed for their use as probes in compact antenna test ranges. For that purpose, the quiet zone generated by a single offset reflectarray is enhanced, overcoming the limitation imposed by the amplitude taper of the feed antenna. First, the near field is characterized by a radiation model which computes the near field of the reflectarray as far field contributions of each element, which are modeled as small rectangular apertures and thus taking into account the active element pattern. Then, a phase only synthesis is performed with the LevenbergMarquardt algorithm in order to improve the size of the generated quiet zone. Due to the nature of the application, this near field synthesis takes into account both the amplitude and phase, making it a more challenging task than an amplitude-only synthesis. The optimization is focused on flattening the amplitude while trying to preserve the phase front generated by the reflectarray.","PeriodicalId":54551,"journal":{"name":"Progress in Electromagnetics Research-Pier","volume":"84 1","pages":"9-17"},"PeriodicalIF":6.7,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79819686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"NON-COIL, OPTIMAL SOURCES FOR WIRELESS POWERING OF SUB-MILLIMETER IMPLANTABLE DEVICES","authors":"Sanghoek Kim, J. S. Ho, A. Poon","doi":"10.2528/PIER16092301","DOIUrl":"https://doi.org/10.2528/PIER16092301","url":null,"abstract":"This paper presents non-coil sources to improve the wireless power transfer efficiency for implantable device used in various medical applications — cardiovascular devices, endoscope in the small intestine, and neurostimulator in the brain. For each application, a bound on the power transfer efficiency and the optimal source achieving such bound are analytically solved. The results reveal that depending on the depth of the implantable devices, power can be transferred to a sub-millimeter scaled receiver with the efficiency ranging from −57 dB to −33 dB, which is up to 6.6 times higher than the performance of existing coil-based source systems. The technique introduced in this paper can be broadly applied to other medical applications.","PeriodicalId":54551,"journal":{"name":"Progress in Electromagnetics Research-Pier","volume":"13 1","pages":"99-108"},"PeriodicalIF":6.7,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72835147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Paladhi, A. Tayebi, P. Banerjee, L. Udpa, S. Udpa
{"title":"Image Reconstruction from Highly Sparse and Limited Angular Diffraction Tomography Using Compressed Sensing Approach","authors":"P. Paladhi, A. Tayebi, P. Banerjee, L. Udpa, S. Udpa","doi":"10.2528/PIER16111501","DOIUrl":"https://doi.org/10.2528/PIER16111501","url":null,"abstract":"Diffraction tomography (DT) from limited projection data has been an active research topic for over three decades. The interest has been steadily fueled due to its application in multiple disciplines including medical imaging, structural health monitoring and non-destructive evaluation to name a few. This paper explores the applicability of compressed sensing to recover complex-valued objective functions (e.g., complex permittivity in microwave tomography). Generally, compressed sensing based tomographic reconstruction has been studied under full angular access. In this paper, the effect of lowering the angular access in addition to highly limited number of projection data is explored. The effectiveness of the reconstruction methods is tested with severely limited dataset which would render reconstruction impossible by traditional iterative approximation methods. Furthermore, results show that complex-valued phantoms can be reconstructed from as few as 15 projections from 120◦ coverage, a significant finding. In this study, the Total Variation (TV) has been used as the l1 norm within the compressed sensing framework. The robustness of the algorithm in presence of noise is discussed. Use of multiple sparse domains has also been explored briefly. The results show the effectiveness of TV as a regularization parameter even for complex-valued images under the compressed sensing regime. This is a pertinent observation as TV is a simple norm to implement. For a large class of images, especially in medical imaging, this implies the availability of a steady l1 norm for easy implementation of compressed sensing reconstruction for complex-valued images.","PeriodicalId":54551,"journal":{"name":"Progress in Electromagnetics Research-Pier","volume":"19 1","pages":"21-36"},"PeriodicalIF":6.7,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76930780","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Analysis on the Calculation of the Inverse Discrete Fourier Transform (IDFT) of Passband Frequency Response Measurements in Terms of Lowpass Equivalent Response","authors":"A. Gifuni, S. Perna","doi":"10.2528/PIER17081703","DOIUrl":"https://doi.org/10.2528/PIER17081703","url":null,"abstract":"An analysis on the calculation of the inverse discrete Fourier transform (IDFT) of passband frequency response measurements in terms of lowpass equivalent responses is shown, in order to specify the differences in the results given from different common algorithms; differences with respect to the calculation of the IDFT for true lowpass responses are remarked. It is shown how the basic sequence has to be represented in time domain by invoking the causality, which is supported by results. Results are corroborated by an application on measured data in a reverberation chamber. The present analysis helps readers understand different IDFT algorithms used by Manufacturers and make their own codes whenever desirable.","PeriodicalId":54551,"journal":{"name":"Progress in Electromagnetics Research-Pier","volume":"15 1","pages":"63-69"},"PeriodicalIF":6.7,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90512668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On the possibility of a perfect power combiner","authors":"Sailing He, Kexin Liu","doi":"10.2528/PIER16092302","DOIUrl":"https://doi.org/10.2528/PIER16092302","url":null,"abstract":"By reductio ad absurdum, we show that a perfect power combiner of single-mode waveguides is impossible for incoherent input waves of the same frequency and same polarization as it is against the la ...","PeriodicalId":54551,"journal":{"name":"Progress in Electromagnetics Research-Pier","volume":"60 1","pages":"1-6"},"PeriodicalIF":6.7,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81186945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"SHAPE RECONSTRUCTION VIA EQUIVALENCE PRINCIPLES,CONSTRAINED INVERSE SOURCE PROBLEMS AND SPARSITY PROMOTION","authors":"M. Bevacqua, T. Isernia","doi":"10.2528/PIER16111404","DOIUrl":"https://doi.org/10.2528/PIER16111404","url":null,"abstract":"A new approach for position and shape reconstruction of both penetrable and impenetrable objects from the measurements of the scattered fields is introduced and described. The approach takes advantage of the fact that for perfect electric conductors the induced currents are localized on the boundary, and equivalent sources also placed on the surface of the scatterers can be considered in the case of dielectric targets by virtue of the equivalence theorem. Starting from these considerations, a new inversion approach is formulated in order to retrieve the location and the boundary of unknown objects. Examples with both numerical and experimental data are given to demonstrate and assess the effectiveness of the method.","PeriodicalId":54551,"journal":{"name":"Progress in Electromagnetics Research-Pier","volume":"500 1","pages":"37-48"},"PeriodicalIF":6.7,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80629883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}