IOSR Journal of Electronics and Communication Engineering(IOSR-JECE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of electronics and communication engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electronics and communication engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Dielectric Resonator Reflectarray Antenna Unit Cells for 5G Applications IJECEIAES
This paper presents an investigation for the performance comparison of three different unit cell configurations operating at 26 GHz for 5G applications. The unit cells are cross shape dielectric resonator, cross microstrip patch and cross hybrid dielectric resonator. Verification of the comparison has been done by simulations using commercial Computer Simulation Technology Microwave Studio (CST MWS). The simulated results for reflection phase, slope variation, reflection loss and 10% bandwidth were analyzed and compared. The results indicate that the optimum configuration to be deployed for the reflectarray’s unit element in order to fulfill the 5G requirements of a wide bandwidth is the cross hybrid DRA. This configuration is a combination of cross DRA with cross microstrip patch as the parasitic element in order to tune the phase and provide a wide phase range with smooth variation slope. Cross hybrid DRA provided a wide phase range of 520° with 0.77 dB loss and 10% bandwidth of 160 MHz.
Design of a Selective Filter based on 2D Photonic Crystals Materials IJECEIAES
Two dimensional finite differences temporal domain (2D-FDTD) numerical simulations are performed in cartesian coordinate system to determine the dispersion diagrams of transverse electric (TE) of a two-dimension photonic crystal (PC) with triangular lattice. The aim of this work is to design a filter with maximum spectral response close to the frequency 1.55 μm. To achieve this frequency, selective filters PC are formed by combination of three waveguides W 1 K A wherein the air holes have of different normalized radii respectively r 1 /a=0.44, r 2 /a=0.288 and r /a= 0.3292 (a: is the periodicity of the lattice with value 0.48 μm). Best response is obtained when we insert three small cylindrical cavities (with normalized radius of 0.17) between the two half-planes of photonic crystal strong lateral confinement.
A New Approach for Solving Inverse Scattering Problems with Overset Grid Gene...TELKOMNIKA JOURNAL
This paper presents a new approach of Forward-Backward Time-Stepping (FBTS)
utilizing Finite-Difference Time-Domain (FDTD) method with Overset Grid Generation (OGG)
method to solve the inverse scattering problems for electromagnetic (EM) waves. The proposed
FDTD method is combined with OGG method to reduce the geometrically complex problem to a
simple set of grids. The grids can be modified easily without the need to regenerate the grid
system, thus, it provide an efficient approach to integrate with the FBTS technique. Here, the
characteristics of the EM waves are analyzed. For the research mentioned in this paper, the
‘measured’ signals are syntactic data generated by FDTD simulations. While the ‘simulated’
signals are the calculated data. The accuracy of the proposed approach is validated. Good
agreements are obtained between simulation data and measured data. The proposed approach
has the potential to provide useful quantitative information of the unknown object particularly for
shape reconstruction, object detection and others.
III-Nitride Semiconductors based Optical Power Splitter Device Design for und...IJECEIAES
In this paper, we introduce III-nitrides based 1× 4 optical power splitter for underwater optical communication applications. To the best of our knowledge, this is a first study for the design of multimode interference (MMI) and four-branch taper waveguide based on GaN/sapphire. The microstructure of GaN semiconductor grown by Metalorganic Chemical Vapor Deposition (MOCVD) on (0001) sapphire reported. The numerical experimental is conducted using the 3D FD-BPM method. The results showed that the optical power splitter has an excess loss of 0.013 dB and imbalance of 0.17 dB. The results open the opportunity for the future device using this technology for the underwater application.
GEOMETRY AND CHARACTERIZATION OF LOW INDEX SILICON MICRO RING RESONATORSoptljjournal
An optical ring resonator is indeed a series of waveguides in which a closed loop coupled with some sort of input and output of light is at least one. The consequence of the index difference on dielectric waveguide characteristics such as single-mode process, losses, efficiency of fiber to waveguide coupling, minimum bending radius, hybridity mode, birefringence, polarization effects, repeatability and stability, integration
size, realizable circuits, technical constraints and usable materials is indeed very significant for study. The purpose of this article is to analyze the effect of the features of the waveguide with regard to the index correlation and to explore the difficulties. This article assesses the effect of the intensity index on the characteristics of the dielectric waveguide, such as the single-mode device, losses, technical constraints and materials available. This work is an approximation for the design of optical waveguides, so that by lowering the silicon index, we can achieve versatility
Regression model for analyzing the dgs structures propagation characterisitcseSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Recent research shows the tremendous potential for the development of optical devices viz. photo-detector, optical sources, connectors and applications etc. This is mainly because of the success of optical communication in the recent for gigabit transmission and is intended for terabits transmission in future. In this paper, mathematical model for the optical dependence of I-V, C-V characteristics of MISFET structure (to be used as photo-detector) is reported. Model is based on solution of Poisson‟s and current continuity equation. Proposed structure of MISFET includes, In0.53Ga0.47As used as substrate material and InP as insulator. Light is made to incident perpendicular to the surface. Drain current can be controlled optically by means of varying light intensity of incident radiation. There is significant effect of intensity modulation on IV and CV characteristics of MISFET. As a result of intensity modulation, drain current increases significantly in presence of illumination mainly due to change in carrier concentration of channel results from photo-generated carriers. Simulation of mathematical model is carried out in MATLAB.
Dielectric Resonator Reflectarray Antenna Unit Cells for 5G Applications IJECEIAES
This paper presents an investigation for the performance comparison of three different unit cell configurations operating at 26 GHz for 5G applications. The unit cells are cross shape dielectric resonator, cross microstrip patch and cross hybrid dielectric resonator. Verification of the comparison has been done by simulations using commercial Computer Simulation Technology Microwave Studio (CST MWS). The simulated results for reflection phase, slope variation, reflection loss and 10% bandwidth were analyzed and compared. The results indicate that the optimum configuration to be deployed for the reflectarray’s unit element in order to fulfill the 5G requirements of a wide bandwidth is the cross hybrid DRA. This configuration is a combination of cross DRA with cross microstrip patch as the parasitic element in order to tune the phase and provide a wide phase range with smooth variation slope. Cross hybrid DRA provided a wide phase range of 520° with 0.77 dB loss and 10% bandwidth of 160 MHz.
Design of a Selective Filter based on 2D Photonic Crystals Materials IJECEIAES
Two dimensional finite differences temporal domain (2D-FDTD) numerical simulations are performed in cartesian coordinate system to determine the dispersion diagrams of transverse electric (TE) of a two-dimension photonic crystal (PC) with triangular lattice. The aim of this work is to design a filter with maximum spectral response close to the frequency 1.55 μm. To achieve this frequency, selective filters PC are formed by combination of three waveguides W 1 K A wherein the air holes have of different normalized radii respectively r 1 /a=0.44, r 2 /a=0.288 and r /a= 0.3292 (a: is the periodicity of the lattice with value 0.48 μm). Best response is obtained when we insert three small cylindrical cavities (with normalized radius of 0.17) between the two half-planes of photonic crystal strong lateral confinement.
A New Approach for Solving Inverse Scattering Problems with Overset Grid Gene...TELKOMNIKA JOURNAL
This paper presents a new approach of Forward-Backward Time-Stepping (FBTS)
utilizing Finite-Difference Time-Domain (FDTD) method with Overset Grid Generation (OGG)
method to solve the inverse scattering problems for electromagnetic (EM) waves. The proposed
FDTD method is combined with OGG method to reduce the geometrically complex problem to a
simple set of grids. The grids can be modified easily without the need to regenerate the grid
system, thus, it provide an efficient approach to integrate with the FBTS technique. Here, the
characteristics of the EM waves are analyzed. For the research mentioned in this paper, the
‘measured’ signals are syntactic data generated by FDTD simulations. While the ‘simulated’
signals are the calculated data. The accuracy of the proposed approach is validated. Good
agreements are obtained between simulation data and measured data. The proposed approach
has the potential to provide useful quantitative information of the unknown object particularly for
shape reconstruction, object detection and others.
III-Nitride Semiconductors based Optical Power Splitter Device Design for und...IJECEIAES
In this paper, we introduce III-nitrides based 1× 4 optical power splitter for underwater optical communication applications. To the best of our knowledge, this is a first study for the design of multimode interference (MMI) and four-branch taper waveguide based on GaN/sapphire. The microstructure of GaN semiconductor grown by Metalorganic Chemical Vapor Deposition (MOCVD) on (0001) sapphire reported. The numerical experimental is conducted using the 3D FD-BPM method. The results showed that the optical power splitter has an excess loss of 0.013 dB and imbalance of 0.17 dB. The results open the opportunity for the future device using this technology for the underwater application.
GEOMETRY AND CHARACTERIZATION OF LOW INDEX SILICON MICRO RING RESONATORSoptljjournal
An optical ring resonator is indeed a series of waveguides in which a closed loop coupled with some sort of input and output of light is at least one. The consequence of the index difference on dielectric waveguide characteristics such as single-mode process, losses, efficiency of fiber to waveguide coupling, minimum bending radius, hybridity mode, birefringence, polarization effects, repeatability and stability, integration
size, realizable circuits, technical constraints and usable materials is indeed very significant for study. The purpose of this article is to analyze the effect of the features of the waveguide with regard to the index correlation and to explore the difficulties. This article assesses the effect of the intensity index on the characteristics of the dielectric waveguide, such as the single-mode device, losses, technical constraints and materials available. This work is an approximation for the design of optical waveguides, so that by lowering the silicon index, we can achieve versatility
Regression model for analyzing the dgs structures propagation characterisitcseSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Recent research shows the tremendous potential for the development of optical devices viz. photo-detector, optical sources, connectors and applications etc. This is mainly because of the success of optical communication in the recent for gigabit transmission and is intended for terabits transmission in future. In this paper, mathematical model for the optical dependence of I-V, C-V characteristics of MISFET structure (to be used as photo-detector) is reported. Model is based on solution of Poisson‟s and current continuity equation. Proposed structure of MISFET includes, In0.53Ga0.47As used as substrate material and InP as insulator. Light is made to incident perpendicular to the surface. Drain current can be controlled optically by means of varying light intensity of incident radiation. There is significant effect of intensity modulation on IV and CV characteristics of MISFET. As a result of intensity modulation, drain current increases significantly in presence of illumination mainly due to change in carrier concentration of channel results from photo-generated carriers. Simulation of mathematical model is carried out in MATLAB.
New implementations for concurrent computing applications of 3D networks using corresponding nano and field-emission controlled-switching components are introduced. The developed implementations are performed within 3D lattice-based systems to perform the required concurrent computing. The introduced 3D systems utilize recent findings in field-emission and nano applications to implement the function of the basic 3D lattice networks using nano controlled-switching. This includes ternary lattice computing via carbon nanotubes and carbon field-emission techniques. The presented realization of lattice networks can be important for several reasons including the reduction of power consumption, which is an important specification for the system design in several future and emerging technologies, and in achieving high performance and reliability realizations. The introduced implementations for 3D lattice computations, with 2D lattice networks as a special case, are also important for the design within modern technologies that require optimal design specifications of high speed, high regularity and ease-of-manufacturability, such as in highly-reliable error-correcting signal processing applications.
Reduction of Mutual Coupling between Closely Spaced Microstrip Antennas Array...TELKOMNIKA JOURNAL
Reducing mutual coupling is a key research area in design of compact microstrip antennas
arrays. To minimize the overall size of the antennas arrays, the distance between them must be very
small, as a result a strong mutual coupling is appears. Periodic structures can help to design a low profile
of antennas arrays and enable to improve their performances by the suppression of surface waves
propagation in a given frequency range. This paper proposes a novel configuration of mushroom-like
electromagnetic band-gap (2D-EBG) structure created by microstrip technology placed between two
antennas arrays to reduce the mutual coupling more than -33.24dB. When 13×2 EBG structures are used,
the mutual coupling reduces to -59.36dB at the operation frequency 5.8GHz of the antennas arrays. A
26.12dB mutual coupling reduction is achieved, which proves that the surface wave is suppressed. The
proposed configuration is designed, optimized, and miniaturized by using electromagnetic software CST
Microwave Studio. The measured results show that there is a good agreement with the computed results.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Evolutionary algorithms for optimum design of thin broadband multilayer micro...eSAT Journals
Abstract In this paper we focused on the comparative study of three very popular and most recently developed nature inspired evolutionary algorithms namely Biogeography based optimization algorithm (BBO), Flower pollination algorithm (FPA) and Artificial bee colony optimization algorithm (ABC) for developing a model of 6 layers thin broadband (0.2-20GHz) microwave absorber. The model is optimized for oblique wide angle of incidence (450, 600) taking both TE and TM polarization of the electromagnetic wave under consideration. The primary goal of our design is to minimizing the overall reflection coefficient of the absorber and its total thickness by selecting the proper layer of materials from a predefined database of existing materials. 8 different models are presented and synthesize considering both these design consideration simultaneously and for only overall reflection coefficient of the absorber while total thickness is not taken into consideration during optimization for each cases. The optimum values of all the significant parameters of the multilayer absorber for different models have been compared and tabulated using BBO, FPA and ABC algorithms which established the superiority of our proposed design. Keywords: Multilayer microwave absorber, Oblique incidence, Broadband, Evolutionary algorithms, Arbitrary polarization
Radiation performance enhancement of an ultra wide band antenna using metamat...IJECEIAES
In this paper, a metamaterial structure based on frequency selective surface (FSS) cell is proposed to achieve an isotropic band-pass filtering response. This filter consists of a planar layer formed by a 3×3 metamaterials cell array with transmittive filtering behavior at 3.5 GHz. This design with 45×45 mm dimension is then integrated in close proximity at distance of 10 mm with an ultra wide band (UWB) antenna to enhance it’ s performances around a 3.5 GHz operating frequency. Simulation results ensure that filter geometry provides the advantage of the angular stability up to to 45 and also polarization modes independency (transverse electric (TE) and transverse magnetic (TM)). In addition, enhancement in antenna radiation pattern characteristics is enhanced especially when the FSS filter layer is integrated at a very close distance from the radiator. Moreover, antenna gain was improved to 3.22 dBi, adaptation of antenna port (S 11 ) was increased to -53.26 dB and antenna bandwidth reduction to 1.7 GHz is also detected. All these performances make the proposed design as a good choice used to shield signals in UWB wireless applications especially for connected object in 5G.
A new approach for impedance matching rotman lens using defected ground struc...journalBEEI
Many recent radar applications and smart antenna are based on the electronically steerable beam in order to increase the performance of targeting the desired scan angle with the high performance of gain and directivity. Scanning angle with ±26o based on Microstrip Rotman lens and design frequency 2.45 GHz is presented in this study. Five beam ports provide five output beams directed the beams in five different scanning angles in the azimuth plane is provided. The traditional matching method by tapering the transmission line in order to guarantee a smooth energy transition from the 50 Ω input ports is replaced by Defected Ground Structure to achieve an acceptable return loss with a linear progressive phase for each beam port. The new approach is providing increasing in the scan angle. Besides, the size miniaturization is achieved by removing the tapering length and reduces the total size of the lens length by 23.67 mm. The proposed model is implemented using Computer Simulation Technology (CST) using the FR-4 substrate and the measurements lead to a good validation.
Miniature design of T-Shaped frequency Reconfigurable antenna for S-Band Appl...IJECEIAES
The article presents a miniature antenna with a simple geometry and a simple approach for reconfiguration. In order to make the T-shaped antenna frequency reconfigurable, we integrated Switches in specific positions. The location of the switches is determined following a study of the distribution of the surface currents of the suggested antenna. Indeed, we found that the insertion of switches in places where the concentrations of surface currents are high is irrelevant. In fact, to redirect current flow, the PIN diodes or RF Switch must be placed in positions where the distribution of the surface currents is of low concentration. These locations facilitate the establishment of new trajectories of the flux of current. As a result, a miniature tunable antenna dimension 20mm*20mm*1.6mm printed on FR4 substrate with 4.4 permittivity and with 0.04 loss tangent, the antenna can be adopted in many communication devices in view of its small size, its low manufacturing cost and performance on frequency sweep, the antenna operates in S-Band with an acceptable band and gain. The antenna is simulated and optimized using CST Microwave Studio.
New modeling approach of laser communication in constellation and through atm...journalBEEI
Laser communication between satellites in the constellation and from the satellites to ground stations offers a gigantic data rate for the users. This principal advantage drives telecom companies to develop this technology to use it like a carrier signal, the most disadvantage of this technology is the need to very complicated pointing systems between the transmitter and the receiver due to a very small beam divergence, continually moving of satellites in orbits and the distance between the satellites (tens of thousands of kilometers). The laser beam suffers continuously from several factors like atmospheric turbulences, internal and external vibrations. All these factors lead to an increase in the bit errors rate and cause degradation in the communication quality. This paper deals with a new method of modelisation of external effects in transmission of signal light from a ground station to the satellite through atmospheric disturbances. Indeed, an in-depth investigation, of the influences of satellite vibrationsinlaser signal transmission between satellites constellation, has been conducted by studying the effect of the intensity of vibrations on the optical signal amplitude. Some solutions are proposed to improve the efficiency of optical satellites communications.
Development and Performance Enhancement of MEMS Helix Antenna for THz Applica...TELKOMNIKA JOURNAL
Interest of Micro-Electromechanical System (MEMS) antennas in Terahertz (THz) applications
has rapidly expanded in recent years due to the advent of accurate Computer Aided Design (CAD) tools.
The very special needs of newly proposed MEMS antennas, especially with a wide bandwidth range,
require advanced optimization procedures of enhancing already established designs. This paper provides
a compact design of a wideband MEMS helix antenna optimized using tree-dimensional High Frequency
Structure Simulator (3D-HFSS) based on Quasi-Newton (Q-N) and Sequential Non Linear Programming
(SNLP) techniques to modify the antenna structure with a high accuracy for the selective band of
frequencies by training the samples and minimizing the error from Finite Element Method- (FEM) based
simulation tool. The helix antenna is presented using MEMS technology and shows high performance
demonstrated by very low return losses of less than -20 to -65 dB for a wide range of frequencies from 2.5
to 5 THz. High antenna geometry precision and efficient performance are finally achieved by rectifying and
synthesizing various tunable parameters embedded in silicon substrate including both helix form and
feeding line parameters.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Backtracking Search Optimization for Collaborative Beamforming in Wireless Se...TELKOMNIKA JOURNAL
Due to energy limitation and constraint in communication capabilities, the undesirable high
battery power consumption has become one of the major issues in wireless sensor network (WSN).
Therefore, a collaborative beamforming (CB) method was introduced with the aim to improve the radiation
beampattern in order to compensate the power consumption. A CB is a technique which can increase the
sensor node gain and performance by aiming at the desired objectives through intelligent capabilities. The
sensor nodes were located randomly in WSN environment. The nodes were designed to cooperate among
each other and act as a collaborative antenna array. The configuration of the collaborative nodes was
modeled in circular array formation. The position of array nodes was determined by obtaining the optimum
parameters pertaining to the antenna array which implemented by using Backtracking Search Optimization
Algorithm (BSA). The parameter considered in the project was the side-lobe level minimization. It was
observed that, the suppression of side-lobe level for BSA was better compared to the radiation
beampattern obtained for conventional uniform circular array.
Adaptive 3D ray tracing approach for indoor radio signal prediction at 3.5 GHzIJECEIAES
This paper explained an adaptive ray tracing technique in modelling indoor radio wave propagation. As compared with conventional ray tracing approach, the presented ray tracing approach offers an optimized method to trace the travelling radio signal by introducing flexibility and adaptive features in ray launching algorithm in modelling the radio wave for indoor scenarios. The simulation result was compared with measurements data for verification. By analyzing the results, the proposed adaptive technique showed a better improvement in simulation time, power level and coverage in modelling the radio wave propagation for indoor scenario and may benefit in the development of signal propagation simulators for future technologies.
A DESIGN AND SIMULATION OF OPTICAL PRESSURE SENSOR BASED ON PHOTONIC CRYSTAL ...prj_publication
ABSTRACT
MOEMS based micro-sized pressure sensor can be developed to detect even
sub-micron range dimension change using the photonic crystal. The applied pressure on the
object will change the dimension of the waveguide carved in the photonic crystal. As a result,
this change in spacing can alter the propagation feature of electromagnetic waves that pass
through them that is changing the transmission spectrum. So, this change can directly be
mapped to pressure on the observed object. In this paper, the pressure sensor using photonic
crystal has been modeled and analyzed.
Design and manufacturing of iris waveguide filters for satellite communicationTELKOMNIKA JOURNAL
We propose in this paper, two bandpass filters in waveguide technology having rectangular symmetrical discontinuities with a half-radius r, designed and operating respectively in the X-Band (9-11.5) GHz and C-Band (3.5-5.5) GHz. These filters consists of eight irises placed symmetrically respectively on standard rectangular waveguides WR90 and WR229 in which resonant irises are inserted. These irises are used to couple the sections very strongly in this filter, which allows the bandwidth to be increased and the matching to be controlled. The comparison between the numerical and electromagnetic results, which we obtained for the filters, constitutes a means of validation of computer simulation technology (CST) environment and Mician for the design of the other circuit elements in the various frequency bands. We observed excellent consistency between the simulation curves and those of the measurements. The results obtained are promising and pave the way for the use of these structures in the fields of telecommunications.
New implementations for concurrent computing applications of 3D networks using corresponding nano and field-emission controlled-switching components are introduced. The developed implementations are performed within 3D lattice-based systems to perform the required concurrent computing. The introduced 3D systems utilize recent findings in field-emission and nano applications to implement the function of the basic 3D lattice networks using nano controlled-switching. This includes ternary lattice computing via carbon nanotubes and carbon field-emission techniques. The presented realization of lattice networks can be important for several reasons including the reduction of power consumption, which is an important specification for the system design in several future and emerging technologies, and in achieving high performance and reliability realizations. The introduced implementations for 3D lattice computations, with 2D lattice networks as a special case, are also important for the design within modern technologies that require optimal design specifications of high speed, high regularity and ease-of-manufacturability, such as in highly-reliable error-correcting signal processing applications.
Reduction of Mutual Coupling between Closely Spaced Microstrip Antennas Array...TELKOMNIKA JOURNAL
Reducing mutual coupling is a key research area in design of compact microstrip antennas
arrays. To minimize the overall size of the antennas arrays, the distance between them must be very
small, as a result a strong mutual coupling is appears. Periodic structures can help to design a low profile
of antennas arrays and enable to improve their performances by the suppression of surface waves
propagation in a given frequency range. This paper proposes a novel configuration of mushroom-like
electromagnetic band-gap (2D-EBG) structure created by microstrip technology placed between two
antennas arrays to reduce the mutual coupling more than -33.24dB. When 13×2 EBG structures are used,
the mutual coupling reduces to -59.36dB at the operation frequency 5.8GHz of the antennas arrays. A
26.12dB mutual coupling reduction is achieved, which proves that the surface wave is suppressed. The
proposed configuration is designed, optimized, and miniaturized by using electromagnetic software CST
Microwave Studio. The measured results show that there is a good agreement with the computed results.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Evolutionary algorithms for optimum design of thin broadband multilayer micro...eSAT Journals
Abstract In this paper we focused on the comparative study of three very popular and most recently developed nature inspired evolutionary algorithms namely Biogeography based optimization algorithm (BBO), Flower pollination algorithm (FPA) and Artificial bee colony optimization algorithm (ABC) for developing a model of 6 layers thin broadband (0.2-20GHz) microwave absorber. The model is optimized for oblique wide angle of incidence (450, 600) taking both TE and TM polarization of the electromagnetic wave under consideration. The primary goal of our design is to minimizing the overall reflection coefficient of the absorber and its total thickness by selecting the proper layer of materials from a predefined database of existing materials. 8 different models are presented and synthesize considering both these design consideration simultaneously and for only overall reflection coefficient of the absorber while total thickness is not taken into consideration during optimization for each cases. The optimum values of all the significant parameters of the multilayer absorber for different models have been compared and tabulated using BBO, FPA and ABC algorithms which established the superiority of our proposed design. Keywords: Multilayer microwave absorber, Oblique incidence, Broadband, Evolutionary algorithms, Arbitrary polarization
Radiation performance enhancement of an ultra wide band antenna using metamat...IJECEIAES
In this paper, a metamaterial structure based on frequency selective surface (FSS) cell is proposed to achieve an isotropic band-pass filtering response. This filter consists of a planar layer formed by a 3×3 metamaterials cell array with transmittive filtering behavior at 3.5 GHz. This design with 45×45 mm dimension is then integrated in close proximity at distance of 10 mm with an ultra wide band (UWB) antenna to enhance it’ s performances around a 3.5 GHz operating frequency. Simulation results ensure that filter geometry provides the advantage of the angular stability up to to 45 and also polarization modes independency (transverse electric (TE) and transverse magnetic (TM)). In addition, enhancement in antenna radiation pattern characteristics is enhanced especially when the FSS filter layer is integrated at a very close distance from the radiator. Moreover, antenna gain was improved to 3.22 dBi, adaptation of antenna port (S 11 ) was increased to -53.26 dB and antenna bandwidth reduction to 1.7 GHz is also detected. All these performances make the proposed design as a good choice used to shield signals in UWB wireless applications especially for connected object in 5G.
A new approach for impedance matching rotman lens using defected ground struc...journalBEEI
Many recent radar applications and smart antenna are based on the electronically steerable beam in order to increase the performance of targeting the desired scan angle with the high performance of gain and directivity. Scanning angle with ±26o based on Microstrip Rotman lens and design frequency 2.45 GHz is presented in this study. Five beam ports provide five output beams directed the beams in five different scanning angles in the azimuth plane is provided. The traditional matching method by tapering the transmission line in order to guarantee a smooth energy transition from the 50 Ω input ports is replaced by Defected Ground Structure to achieve an acceptable return loss with a linear progressive phase for each beam port. The new approach is providing increasing in the scan angle. Besides, the size miniaturization is achieved by removing the tapering length and reduces the total size of the lens length by 23.67 mm. The proposed model is implemented using Computer Simulation Technology (CST) using the FR-4 substrate and the measurements lead to a good validation.
Miniature design of T-Shaped frequency Reconfigurable antenna for S-Band Appl...IJECEIAES
The article presents a miniature antenna with a simple geometry and a simple approach for reconfiguration. In order to make the T-shaped antenna frequency reconfigurable, we integrated Switches in specific positions. The location of the switches is determined following a study of the distribution of the surface currents of the suggested antenna. Indeed, we found that the insertion of switches in places where the concentrations of surface currents are high is irrelevant. In fact, to redirect current flow, the PIN diodes or RF Switch must be placed in positions where the distribution of the surface currents is of low concentration. These locations facilitate the establishment of new trajectories of the flux of current. As a result, a miniature tunable antenna dimension 20mm*20mm*1.6mm printed on FR4 substrate with 4.4 permittivity and with 0.04 loss tangent, the antenna can be adopted in many communication devices in view of its small size, its low manufacturing cost and performance on frequency sweep, the antenna operates in S-Band with an acceptable band and gain. The antenna is simulated and optimized using CST Microwave Studio.
New modeling approach of laser communication in constellation and through atm...journalBEEI
Laser communication between satellites in the constellation and from the satellites to ground stations offers a gigantic data rate for the users. This principal advantage drives telecom companies to develop this technology to use it like a carrier signal, the most disadvantage of this technology is the need to very complicated pointing systems between the transmitter and the receiver due to a very small beam divergence, continually moving of satellites in orbits and the distance between the satellites (tens of thousands of kilometers). The laser beam suffers continuously from several factors like atmospheric turbulences, internal and external vibrations. All these factors lead to an increase in the bit errors rate and cause degradation in the communication quality. This paper deals with a new method of modelisation of external effects in transmission of signal light from a ground station to the satellite through atmospheric disturbances. Indeed, an in-depth investigation, of the influences of satellite vibrationsinlaser signal transmission between satellites constellation, has been conducted by studying the effect of the intensity of vibrations on the optical signal amplitude. Some solutions are proposed to improve the efficiency of optical satellites communications.
Development and Performance Enhancement of MEMS Helix Antenna for THz Applica...TELKOMNIKA JOURNAL
Interest of Micro-Electromechanical System (MEMS) antennas in Terahertz (THz) applications
has rapidly expanded in recent years due to the advent of accurate Computer Aided Design (CAD) tools.
The very special needs of newly proposed MEMS antennas, especially with a wide bandwidth range,
require advanced optimization procedures of enhancing already established designs. This paper provides
a compact design of a wideband MEMS helix antenna optimized using tree-dimensional High Frequency
Structure Simulator (3D-HFSS) based on Quasi-Newton (Q-N) and Sequential Non Linear Programming
(SNLP) techniques to modify the antenna structure with a high accuracy for the selective band of
frequencies by training the samples and minimizing the error from Finite Element Method- (FEM) based
simulation tool. The helix antenna is presented using MEMS technology and shows high performance
demonstrated by very low return losses of less than -20 to -65 dB for a wide range of frequencies from 2.5
to 5 THz. High antenna geometry precision and efficient performance are finally achieved by rectifying and
synthesizing various tunable parameters embedded in silicon substrate including both helix form and
feeding line parameters.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Backtracking Search Optimization for Collaborative Beamforming in Wireless Se...TELKOMNIKA JOURNAL
Due to energy limitation and constraint in communication capabilities, the undesirable high
battery power consumption has become one of the major issues in wireless sensor network (WSN).
Therefore, a collaborative beamforming (CB) method was introduced with the aim to improve the radiation
beampattern in order to compensate the power consumption. A CB is a technique which can increase the
sensor node gain and performance by aiming at the desired objectives through intelligent capabilities. The
sensor nodes were located randomly in WSN environment. The nodes were designed to cooperate among
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Time Domain Modelling of Optical Add-drop filter based on Microcavity Ring Resonators
1. IOSR Journal of Electronics and Communication Engineering (IOSR-JECE)
e-ISSN: 2278-2834,p- ISSN: 2278-8735.Volume 10, Issue 6, Ver. II (Nov - Dec .2015), PP 77-87
www.iosrjournals.org
DOI: 10.9790/2834-10627787 www.iosrjournals.org 77 | Page
Time Domain Modelling of Optical Add-drop filter based on
Microcavity Ring Resonators
Nabeil A. Abujnah1
, Rosa Letizia2
, Fathi Alwafie3
, Salah Obayya4
1
Department of Electrical and Electronic Engineering, Faculty of Engineering, University of Azzaytuna-Libya
2
Engineering Department, Lancaster University, Lancaster, LA1 4YR.UK
3
Department of Electrical and Electronic Engineering, Faculty of Science Engineering and Technology,
University of Sebha-Libya.
4
Centre for Photonics and Smart Materials, Zewail City of Science and Technology, Sheikh Zayed District, 6th
of
October city, Giza, Egypt
Abstract: In this paper an accurate analysis of two-dimensional (2D) coupled ring resonators based on high-
index-contrast is carried out. The normalized transmission spectra for single-ring and double-ring
configuration have been investigated by using a robust and accurate Multiresolution Time Domain (MRTD)
technique with conjunction with uniaxial perfectly matched layer (UPML) absorbing boundary condition that
rigorously terminate the computational window. The resonant-mode quality factors (Q), free spectral range
(FSR) are numerically investigated. The variation of the structure parameters such as the symmetric and
asymmetric gap size (g) lead to dramatic changes of Q and the extinction ratio of the device. Studies of the
transmission characteristics for the ring diameter of 3.4 μm shows the possibility for achieving Q’s in several
thousands and FSR of 9 THZ (80nm) in the 1.55 μm wavelength range.
Keywords:- multiresolution time domain, microcavity, numerical analysis ring resonators,, time domain
methods.
I. Introduction
Recent advances in micro and nanofabrication technology have brought a new interest in building
optical devices with physical dimension comparable to optical wavelength [1, 2]. In particular, microcavity
resonators based on whispering-gallery-modes (WGMs) play significant role in many applications ranging from
quantum electrodynamics to telecommunication devices and optical sensors [3-8] . At particular wavelength,
light in the bus line waveguide can evanescently coupled through the gap into WGM of the resonator if proper
phase matching conditions exist. By means of refractive index contrast between core and cladding, light which
is travelling in medium of circular geometry such as rings can be resonantly confined by total internal reflection
(TIR)[9]. These modes can resonate with high quality factor (Q) in the cavity where the long photons lifetimes
allow the field within the cavity to be built from a considerably weaker input [10] [11]. Historically, the original
concept of an optical ring resonator is back date to 1969[12], where relatively optical ring resonators made in
direct laser written polymers[13], and ion-exchanged glass substrates[14], were demonstrated. However, due to
low-index-contrast between the resonators medium and the surrounding material, the radius needed to be of the
order of several centimetres to bend losses [1] [15]. In the last few years, research interest has been strongly
directed to the design of optical ring resonators based on high-index-contrast semiconductor materials [1, 16,
17] . These research efforts have clearly demonstrated that these structures naturally permit realisation of small-
radius microcavities with negligible bending losses resulting in large longitudinal mode spacing. For this reason,
they enable the integration of a large number of devices on optical circuits foreseen for very large scale
integrated (VLSI) photonics [1]. For active device applications, wide range of research studies can be found in
literature on strongly guiding semiconductor ring laser with diameters ranging from 10 to 500 µm. and large
waveguide width from 4 to 20 µm [18] [19] [20]. In order to acquire light output, these ring resonators are
coupled to output by means of Y junction. Thanks to existing semiconductor fabrication techniques, light in the
bus waveguide can be evanescently coupled through the gap into whispering gallery mode of the resonator if the
proper phase matching conditions exist. Optical microring resonators (MRRs) based on high-index-contrast
semiconductor waveguides are able to support strongly confined WGMs with diameters as small as 1-2 µm[1].
If the free spectral range (FSR) of the ring can be made wide enough to accommodate the set of WDM channels
within the communication window, one can achieve the goal of dropping one channel by one filter without
affecting the other channels. To ensure a FSR larger than the optical communication window (30nm), a ring
radius of less than 5 μm is required. Since the MRRs have been recognised as complicated structures and cannot
be analysed by using simple techniques, the characterisation of these devices usually necessitates a full-wave
electromagnetic simulator. In order to choose a particular simulation approach, generally two criteria have to be
taken into account. Firstly, the desired results needed to be accomplished with available resources and secondly,
2. Time Domain Modelling of Optical Add-drop filter based on Microcavity Ring Resonators
DOI: 10.9790/2834-10627787 www.iosrjournals.org 78 | Page
CPU simulation time has to be optimised to obtain these results. Since the first aspect is related to the
convergence rate of the used techniques, large computational problems can be studied with a highly convergent
algorithm. On the other side, the execution simulation time not only relies on the cost of time per time step but
also depends on the number of time steps that have to be carried out. Among the existing full-wave techniques,
Finite Difference Time Domain (FDTD) is known as a popular framework for low-cost feasibility studies and
permits design optimisation before fabricating the device[1]. Although this technique is straightforward and
adaptable, it puts a heavy burden on computer resources specially when modelling complex problems with large
computational volumes. The more sophisticated MRTD technique used here to analyse MRR devices [21-23].
This technique was introduced by Krumpholz and Katehi in 1996 [24] for the microwave range and has been
recently extended also for the optical range [23]. This method uses a high order of approximation of derivative
in space to reduce the numerical phase error of FDTD. By doing so, MRTD does not require the use of a very
fine mesh size to discretise the structure geometry and high numerical accuracy can be achieved while
mitigating the computational burden. Therefore, the possibility of saving CPU running time makes the MRTD
an efficient alternative numerical scheme to the commonly used FDTD for the design of microring structures. In
this paper, MRTD has been used to analyse the transmission characteristics of different order of MRR. The
analysis is mainly focused on the extraction of different resonant mode where different investigation have been
carried out to explore the effect of different parameters of the structure on transmitted and coupled power.
Parameter such as gap size, the distance between two rings and the width of ring and waveguide have been
varied and sets of different results have been presented. This paper is organized as following. Following this
introduction, a brief mathematical analysis is given in section 2. The simulation results are presented in section
3. Finally conclusions are drawn.
II. Analysis
Starting from Maxwell’s equation and for 2D structures in x-z plane, the transverse electrical mode
(TE) with a components Ey, Hx and Hz is derived under assumption that y-axis is the homogeneous direction
and the x-axis as the propagation direction.
z
E
t
H yx
0
1
(1a)
x
E
t
H yz
0
1
(1b)
x
H
z
H
t
E zx
r
y
0
1
(1c)
With respect to the unit cell shown in Fig. 1, the electromagnetic fields are expanded as combination of
scaling function in space and Haar function in time using
)()()(),,(
2
1
2
1
2
1
,
2
1
,
2
1
,, 2
1 thzxEtzxE
nji
y
ji
jin
n
y
(2)
where n, i, and j are the discrete indexes in time and in space respectively, Φ is the scaling function
representing the sampling in space, h is the Haar function, and
,
2
1
,
2
1
2
1
y
jin
E
is the expansion coefficient for Ey
component on which the iterative process of update is applied on.
3. Time Domain Modelling of Optical Add-drop filter based on Microcavity Ring Resonators
DOI: 10.9790/2834-10627787 www.iosrjournals.org 79 | Page
Figure 1: Electrical and magnetic field expansion as placed inside 2-D MRTD unit cell.
Substituting the field expansions in the form of (4) into the scalar Maxwell’s equations and testing
them with the dual of the biorthogonal scaling function m
~
(with m= i,j) , by applying the method-of-moments,
lead to the discretised update equations [23]:
,
2
1
,
2
1
1
2
1
0
,
,
2
1
,
,
2
11 )( y
lji
L
Ll
n
x
ji
n
x
ji
n Ela
t
t
HH
s
s
(3a)
,
2
1
,
2
1
1
2
1
0
,
2
1
,
,
2
1
,
1 )( y
jli
Ls
Ll
n
z
ji
n
z
ji
n Ela
x
t
HH
s
(3b)
1
,
2
1
,1
,
2
1
,
2
1
2
1
,
2
10
,
2
1
,
2
1
2
1
,
2
1
,
2
1
2
1
11
)(
s
s
L
Ll
z
jli
n
x
ji
n
ji
y
jin
y
jin
H
x
H
z
la
t
EE
(3c)
where µ0, ε0 are permeability and permittivity of the free space respectively, ε is the relative permittivity of the
medium, and Δt is time step. Δx and Δz are the spital increments in the direction of x and y respectively. The
‘stencil size’ Ls stand for the effective support of the basis function that determines the number of expansion
coefficients considered in the summation and it is equal to 5 for CDF(2,4), while a(l) represent the connection
coefficients that can be numerically calculated using [23]
1
,
2
1
'
'
)(
)(
)(
s
s
L
Ll
ili
i
i ladx
x
x
x
(4)
The values of the connection coefficients a(l) for the case of CDF(2,4) are reported in [22].
In order to ensure the numerical stability of the MRTD scheme, the time interval Δt has to be smaller
than a certain limit, as follows
0c
st
(5)
with
1
0
)(2
1
sL
l
la
s (6)
4. Time Domain Modelling of Optical Add-drop filter based on Microcavity Ring Resonators
DOI: 10.9790/2834-10627787 www.iosrjournals.org 80 | Page
where Δ=Δx=Δz, c0 is the speed of the light, and the Courant number s represents the stability factor which is
conveniently fixed to 0.1 through the paper [23].
The uniaxial perfectly matched layers (UPML) are a very efficient and robust way to terminate the
computational domain with layers of artificial absorbers that capable of very-low reflection and it has been
successfully incorporated with MRTD scheme as boundary conditions. As an example, the discretised equations
to update Ey component through the displacement vector Dy are reported here
x
H
z
H
la
t
t
D
t
t
D
z
jli
n
x
lji
nL
Llz
y
ji
n
z
zy
jin
s
s
,
2
1
,1
,
1,
2
11
0
0
,
2
1
,
2
1
0
0,
2
1
,
2
1
2
1
)(
2
2
2
2
)7( a
,
2
1
,
2
1
2
1
,
2
1
,
2
1
2
1
0
2
1
,
2
10
0
,
2
1
,
2
1
0
0,
2
1
2(
2
2
2
2
1
,
2
1
y
jin
y
jin
x
ji
y
ji
n
x
xy
n
DD
t
E
t
t
E ji
)7( b
where ε is the relative permittivity of the medium, and σx and σz are the electric conductivities of the UPML
along x and z direction, respectively. Analogue equations are derived for the magnetic field components [23].
For the best performance of UPML absorbing boundary conditions, the parameter, σi (i=x, z) is chosen
to vary in space as
m
m
i
d
i
i max
)(
(8)
where i=x, z, d is the depth of the UPML, and m stands for the order of the polynomial variation. The choice of
σmax that minimises reflection from the boundaries is [25]
r
m
150
)1(
max (9)
where Δ is the spatial discretisation adopted, i=x, z, d is the depth of the UPML, and m stands for the order of
the polynomial variation. The choice of σmax that minimises reflection from the boundaries is [25]
r
m
150
)1(
max (9)
where Δ is the spatial discretisation adopted.
III. Results And Discussion
As a first structure, the single MRR shown in Fig. 2 has been considered where the width W = 0.3 µm, the ring
diameter d = 3.4 µm, and the core and the cladding have refractive indices of ncore = 3.2 and ncl = 1 respectively.
5. Time Domain Modelling of Optical Add-drop filter based on Microcavity Ring Resonators
DOI: 10.9790/2834-10627787 www.iosrjournals.org 81 | Page
Figure 2: Schematic of microring resonator coupled to two straight waveguides.
The structure is discretised into a uniform mesh with cell size Δx = Δz = Δ = 27.25 nm and is terminated
by 20-cell UPML to absorb the reflected power. . It is important to notice that the chosen Δ is about twice the
value required by previous analysis of MRR structures by means of FDTD as found in [1]. Where the same level
of accuracy can be achieved and the possibility to save the CPU running time also can be obtained. A Gaussian
shaped pulse in space with central frequency f = 200 THz (λ = 1.5µm), modelled with Gaussian pulse in time,
has been used to excite the structure to cover the frequency range of interest. As shown in Fig. 2, different cross-
sections are chosen in order to record the time domain variation the incident, transmitted, and reflected fields.
By means of Fast Fourier Transform (FFT) of the recoded time-dependent fields , the coupled power at port C
and the transmitted power at port B are calculated by dividing the coupled and transmitted spectra by incident
spectrum at port A, respectively. The effect of the gap size, g on coupled power, κ and Q is shown in Fig.3 at
the resonance mode of 1503 nm.
Figure 3: Effects of the gap width on the resonance quality factor and coupling coefficients.
6. Time Domain Modelling of Optical Add-drop filter based on Microcavity Ring Resonators
DOI: 10.9790/2834-10627787 www.iosrjournals.org 82 | Page
It is apparent hat increase of g has significant effect on both Q and κ. Since with the increase in gap
size, the coupling efficiency of the resonance modes decreases due to a small fraction of power exchanged,
while the Q value increases. The coupling efficiency can be enhanced in order to compensate the losses in the
cavity and this will improve the transmission. However, the quality factor will be degraded. For this reason, the
optimum values of gap size need to be carefully chosen in order to achieve reasonable high quality factor, while
the coupling efficiency is within desirable range. According to Fig. 3, a good compromise can be achieved by
choosing the g = 218 nm where the values of the κ and Q are 1.024 % and 3098 respectively. Next, the
transmission at port B for 3.4 µm-diameter ring and 218 nm of g is considered.
The measured transmission spectrum of single-ring resonator around λ = 1.55 μm is presented in Fig. 4.
Figure 4: MRTD-computed Transmission for 1.7-µm-radius microring resonator coupled to straight 0.3-µm-
wide waveguides.
From this figure, the localised resonance wavelength and Q’s and corresponding coupling efficiency are listed in
table I.
TABLE I Resonance Data from Fig.4 for 3.4 μm-Diameter MRR and w = 0.3 μm
m F (THz) λres(nm) Q
18 181.2 1655.62 1295
19 190.3 1576.45 1455
20 199.4 1504.51 3098
21 208.5 1438.84 2937
22 217.6 1378.67 3680
The Q’s of the mth
resonance is extracted directly from power spectrum by forming the ratio of the
resonant wavelength (λm) to the width of the resonance (δλ) at the half-power points. The FSR which defined as
the spacing between two adjacent resonant wavelengths ranges between 60 to 80 nm. The rejection ratio or
on/off ratio which is the ratio of power transmitted at resonance wavelength to the power not transmitted at
resonance wavelength is approximately 6dB. Fig.5 shows the variation of extinction ration as a function of gap
size.
7. Time Domain Modelling of Optical Add-drop filter based on Microcavity Ring Resonators
DOI: 10.9790/2834-10627787 www.iosrjournals.org 83 | Page
Figure 5: Effects of the gap width on the on-off ratio.
As can been seen from Fig. 5, the extinction ration can be altered by varying the coupling efficiency, κ.
However, the Q will be also affected in this manner as indicated from Fig. 3. Even though the rejection ration
required being large enough to minimize the crosstalk, the quality factor needed to be high in some application
related to WDM. In order to increase the extinction ratio while the reasonable quality factor can be also
obtained, double parallel microcavity ring resonators (DPMRR) is suggested. The structure, shown in Fig. 6
consists of two parallel ring resonators centred between two straight waveguides.
Figure.6: parallel coupled microring resonators, double ring case.
The following selections of parameters are chosen as following: the diameters of all rings are d = 3.4
µm, the core and the cladding have refractive indices of ncore = 3.2 and ncl = 1 respectively, the widths of all
rings and straight waveguides are W = 0.3 µm, the gap width between the outer rings and straight waveguides is
set to be 218 nm. The structure is excited in the same manner as in single ring. The distance from centre to
centre denoted by Λ between two rings is set to 5 μm. The transmission characteristic shown in Fig. 7 is
achieved using DPMRR.
8. Time Domain Modelling of Optical Add-drop filter based on Microcavity Ring Resonators
DOI: 10.9790/2834-10627787 www.iosrjournals.org 84 | Page
Figure.7: MRTD-computed Transmission for 1.7-µm-radius double microring resonator coupled to straight 0.3-
µm-wide waveguides where the distance between two rings is 5 µm.
The localised resonance wavelength is extracted and Q’s of the mth
resonance is calculated directly from power
spectrum in the same manner as in single ring case. These results are listed in table II.
Table II Resnance Data From Fig. 7 For 3.4-μm-Diameter PDMRR and w = 0.3 μm
m F (THz) λres(nm) Q
18 181.2 1655.62 1242
19 190.3 1576.45 1312
20 199.4 1504.51 2819
21 208.5 1438.84 3284
22 217.6 1378.67 3666
As shown in this table, there is slightly change in the quality factor. While the on- off ratio ranges
between 4 to 11 dB at different resonance wavelengths. The effect of changes in the gap size between the input
and output waveguides and the ring is considered. Two types of changes of g1 and g2 are discussed. Change
both gap identically, and change only one of the gap size while keeping the other constant. Figure 8 and 9 show
the effect of the symmetrical change where g1= g2 =191 nm and asymmetrical change where g1=191 nm and
g2=245 nm. The distance between two rings set to Λ=5µm. Based on the coupling which decreases at high
frequencies, the Q should increase with frequency. Such behaviour is observed in Fig. 8.
9. Time Domain Modelling of Optical Add-drop filter based on Microcavity Ring Resonators
DOI: 10.9790/2834-10627787 www.iosrjournals.org 85 | Page
Figure.8: Effects of symmetrical and asymmetrical change of both separation distances on the quality factor.
However, as the gap width g1, g2 are reduced, the coupling efficiency between the straight input
waveguide and the cavity increases while the transmitted power at throughout port decreases. Due to the
decrease in the level of transmitted power at throughout port higher on-off ratio is achieved while the level of
the Q is decreased. Figure 9 shows the MRTD results for DPMRR for asymmetric gap width.
Figure. 9: Effects of symmetrical and asymmetrical change of both separation distances on the on-off ratio.
Keeping the gap width g1 constant and g2 is increased, and then the coupling between the input
waveguide and the cavity increases. Due to the increase the level of coupling power, the level of transmitted
power at throughout port decreases. On the other hand, keeping the gap width g1 constant, if g2 is increased,
then the coupling between the output waveguide and the cavity decreases. As more power is remained in the
cavity, the Q is increased while the level of on-off ratio decreases. Figure 10 shows the electric field pattern
between the waveguide and the cavity when a sinusoidal continues wave has been injected and reached the
steady state. The wavelength of the sinusoidal is fixed at 1655 nm (181.2 THz). As shown in this figure, nearly
100 % of the power is switched to the cavity which in turn switched to the output waveguide.
10. Time Domain Modelling of Optical Add-drop filter based on Microcavity Ring Resonators
DOI: 10.9790/2834-10627787 www.iosrjournals.org 86 | Page
Figure.10: Sinusoidal steady-state amplitude distributed in 1.7-µm-radius microring resonator: ON-resonance
at 1655 nm
In the same manner, the steady-state E-field is computed for excitation at nonresonant wavelength 1615
nm (185.7 THz) is illustrated in Fig 11. As shown in this figure, no coupling occurred between the input
waveguide and the cavity and 100 % of the signal is transmitted at output at port B.
Figure.11: Sinusoidal steady-state amplitude distributed in 1.7-µm-radius microring resonator: OFF-resonance
at 1615 nm
IV. Conclusion
In this paper, optical microcavity ring resonator based on high-index-contrast waveguide have been
analysed by using MRTD formulation based on CDF (2, 4) scaling function and rigorous UPML boundary
conditions. The approach has proved good level of accuracy in extracting and studying the resonance behaviour
of this structure. The optimisation of a number of important parameters, including coupling coefficients, quality
factor, and rejection ratio has been discussed. A high-order structure consisting of a two ring resonators in
parallel with centre distance of 10 µm has shown interesting potential in increasing the on-off ratio where it is
desirable to minimise the cross talk of the device. Furthermore, by using asymmetric gap sizes, the rejection
ratio of the device has significantly increased of about 60 %, compared to the best result as in the symmetric gap
size case.
11. Time Domain Modelling of Optical Add-drop filter based on Microcavity Ring Resonators
DOI: 10.9790/2834-10627787 www.iosrjournals.org 87 | Page
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