This paper studies the dispersion characteristics of a modified photonic band-gap slow-wave structure with an open boundary by simulation and experiment.A mode launcher with a wheel radiator and a coupling probe is pr...This paper studies the dispersion characteristics of a modified photonic band-gap slow-wave structure with an open boundary by simulation and experiment.A mode launcher with a wheel radiator and a coupling probe is presented to excite a pure TM 01-like mode.The cold test and simulation results show that the TM 01-like mode is effectively excited and no parasitic modes appear.The dispersion characteristics obtained from the cold test are in good agreement with the calculated results.展开更多
This paper presents a three-dimensional particle-in-cell (PIC) simulation of a Ka-band relativistic Cherenkov source with a slow wave structure (SWS) consisting of metal photonic band gap (PBG) structures. In the simu...This paper presents a three-dimensional particle-in-cell (PIC) simulation of a Ka-band relativistic Cherenkov source with a slow wave structure (SWS) consisting of metal photonic band gap (PBG) structures. In the simulation, a perfect match layer boundary is employed to absorb passing band modes supported by the PBG lattice with an artificial metal boundary. The simulated axial field distributions in the cross section and surface of the SWS demonstrate that the device operates in the vicinity of the π point of a TM01-like mode. The Fourier transformation spectra of the axial fields as functions of time and space show that only a single frequency appears at 36.27 GHz, which is in good agreement with that of the intersection of the dispersion curve with the slow space charge wave generated on the beam. The simulation results demonstrate that the SWS has good mode selectivity.展开更多
This paper stuides numerically the model equation in a one dimensional defective photonic lattice by modifying the potential function to a periodic function. It is found that defect modes (DMs) can be regarded as Bloc...This paper stuides numerically the model equation in a one dimensional defective photonic lattice by modifying the potential function to a periodic function. It is found that defect modes (DMs) can be regarded as Bloch modes which are excited from the extended photonic band-gap structure at Bloch wave-numbers with k x = 0. The DMs for both positive and negative defects are considered in this method.展开更多
Band structures of one-dimensional(1D)photonic crystals(PCs)containing dispersive left-handed meta- materials are studied theoretically.The results show that the structure possesses a type of photonic band gap origina...Band structures of one-dimensional(1D)photonic crystals(PCs)containing dispersive left-handed meta- materials are studied theoretically.The results show that the structure possesses a type of photonic band gap originating from total internal reflection(TIR).In contrast to photonic band gaps corresponding to zero average refractive index and zero phase,the TIR gap exhibits sharp angular effect and has no po- larization effect.It should also be noted that band structures of transverse electric(TE)and transverse magnetic(TM)mode waves are exactly the same in the PCs we studied.展开更多
Two-dimensional function photonic crystals, in which the dielectric constants of medium columns are the functions of space coordinates , are proposed and studied numerically. The band gaps structures of the photonic c...Two-dimensional function photonic crystals, in which the dielectric constants of medium columns are the functions of space coordinates , are proposed and studied numerically. The band gaps structures of the photonic crystals for TE and TM waves are different from the two-dimensional conventional photonic crystals. Some absolute band gaps and semiDirac points are found. When the medium column radius and the function form of the dielectric constant are modulated, the numbers, width, and position of band gaps are changed, and the semi-Dirac point can either occur or disappear. Therefore,the special band gaps structures and semi-Dirac points can be achieved through the modulation on the two-dimensional function photonic crystals. The results will provide a new design method of optical devices based on the two-dimensional function photonic crystals.展开更多
Two kinds of compact electromagnetic band gap (EBG) structures are designed.A two layer compact EBG structure configured with cross spiral shape line inductors and interdigital capacitors is first presented.Because of...Two kinds of compact electromagnetic band gap (EBG) structures are designed.A two layer compact EBG structure configured with cross spiral shape line inductors and interdigital capacitors is first presented.Because of its significantly enlarged equivalent inductor and capacitance,the period of the lattice is approximately 4.5% of the free space wavelength.By insetting several narrow slits in the ground plane,the bandwidth of the main bandgap is enhanced by nearly 19%.Further effort has been made for designing a three layer compact EBG structure.Simulation results show that its period is reduced by about 26% compared to that of proposed two layer EBG structure,and the bandwidth of the main bandgap is about 3 times as that of the proposed two layer EBG structure.The detailed designs including a two layer compact 3×7 EBG array with and without defect ground plane and the three layer EBG array are given and simulation results are presented.展开更多
Different feeding techniques of microstrip patch antennas with different spiral defected ground structures are presented in this paper. The investigated structures illustrate some merits in designing multi-electromagn...Different feeding techniques of microstrip patch antennas with different spiral defected ground structures are presented in this paper. The investigated structures illustrate some merits in designing multi-electromagnetic band-gap structures by adjusting the capacitance and changing the inductance through varying the width and length of spiral defected ground structure. Then by applying the three different spirals shapes (one, two and four arms) as the ground plane of microstrip patch antenna with different feeding techniques to create multi or ultra wide-band, improve the antenna gain and reduce the antenna size, it is found that the four arms spiral defected ground structure of microstrip patch antenna with offset feed gives good performance, electrical size reduction to about 75% as compared to the original patch size and ultra-wide bandwidth extends from 2 GHz up to 12 GHz with ?8 dB impedance bandwidth.展开更多
We show theoretically that range of reflection bands and defect modes inside the band gap can be tuned by using a one-dimensional tilted photonic crystal (TPC) structure. A TPC structure is similar to the conventional...We show theoretically that range of reflection bands and defect modes inside the band gap can be tuned by using a one-dimensional tilted photonic crystal (TPC) structure. A TPC structure is similar to the conventional PC structure with the only difference that in this case alternate layers are inclined at certain angle in the direction of periodicity of the structure. In order to obtain the reflectance spectra of the proposed structure transfer matrix method (TMM) has been employed. From the analysis of the reflectance curve, it is found that 100% reflectance range can be varied and enhanced by using TPC structure for both (TE- and TM-) polarizations. The enhancement in reflection bands increases as the tilt angle increases for both the polarizations and hence the enlarged omni-reflectance bands are obtained. Further, we study the properties of the defect modes in TPC structure by introducing the tilted defect at the different tilt angle. The results show that defect modes (tunneling modes) can be tuned at different wavelengths by changing the tilt angle of the structure without changing other parameters. Finally, the effect of variation thickness of defect layers on the tunneling mode has been studied for both TPC and conventional PC structure. The proposed model might be used as a tunable broadband omnidirectional reflector as well as tunable tunneling or transmission mode, which has potential applications in the field of photonics and optoelectronics.展开更多
Optical features of a semiconductor–dielectric photonic crystal are studied theoretically. Alternating layers of micrometer sized SiO2/In Sb slabs are considered as building blocks of the proposed ideal crystal. By i...Optical features of a semiconductor–dielectric photonic crystal are studied theoretically. Alternating layers of micrometer sized SiO2/In Sb slabs are considered as building blocks of the proposed ideal crystal. By inserting additional layers and disrupting the regularity, two more defective crystals are also proposed. Photonic band structure of the ideal crystal and its dependence on the structural parameters are explored at the first step. Transmittance of the defective crystals and its changes with the thicknesses of the layers are studied. After extracting the optimum values for the thicknesses of the unit cells of the crystals, the optical response of the proposed structures at different temperatures and incident angles are investigated. Changes of the defect layers’ induced mode(s) are discussed by taking into consideration of the temperature dependence of the In Sb layer permittivity. The results clearly reflect the high potential of the proposed crystals to be used at high temperature terahertz technology as a promising alternative to their electronic counterparts.展开更多
It is of great significance to present a photonic crystal lattice structure with a wide photonic bandgap. A two-dimension complex lattice photonic crystal is proposed. The photonic crystal is composed of complex latti...It is of great significance to present a photonic crystal lattice structure with a wide photonic bandgap. A two-dimension complex lattice photonic crystal is proposed. The photonic crystal is composed of complex lattices with triangular structure, and each single cell is surrounded by six scatterers in an hexagon. The photonic band gaps are calculated based on the plane wave expansion (PWE) method. The results indicate that the photonic crystal has tunable large TM polarization band gap, and a gap-midgap ratio of up to 45.6%.展开更多
In this paper, we investigate the optical transmission properties of perfect and defective two-segment-connected triangular waveguide networks(2SCTWNs) and find that after introducing defects in networks, many groups ...In this paper, we investigate the optical transmission properties of perfect and defective two-segment-connected triangular waveguide networks(2SCTWNs) and find that after introducing defects in networks, many groups of transparent extreme narrow photonic passbands(ENPPs) will be created in the middle of the transmission spectra, the number for each group and the group number of ENPPs can be adjusted by the matching ratios of waveguide length(MRWLs), the number of defects, and the number of unit cells of 2SCTWNs. The influences of MRWL, number of defects, and number of unit cells on the number, width, and position of these ENPPs are researched and a series of quantitative rules and properties are obtained. It may be useful for the designing of high-sensitive optical switches, wavelength division multiplexers,extreme-narrowband filters, and other correlative waveguide network devices.展开更多
Band gap characteristics of the photonic crystals in terahertz range with square lattice and triangular lattice of GaAs cylinders are comparatively studied by means of plane wave method (PWM). The influence of the rad...Band gap characteristics of the photonic crystals in terahertz range with square lattice and triangular lattice of GaAs cylinders are comparatively studied by means of plane wave method (PWM). The influence of the radius on the band gap width is analyzed and the critical values where the band gap appears are put forward. The results show that the maximum band gap width of photonic crystal with triangular lattice of GaAs cylinders is much wider than that of photonic crystal with square lattice. The research provides a theoretic basis for the development of te rahertz (THz) devices.展开更多
Knowledge of the band gap and transmission and reflection spectrum of a photonic crystal is essential elements for their design. A graphical interface that quickly determines the banding pattern and spectrum based on ...Knowledge of the band gap and transmission and reflection spectrum of a photonic crystal is essential elements for their design. A graphical interface that quickly determines the banding pattern and spectrum based on the Plane Wave Method (PWM) and coupled modes method (CMM) respectively is created. It is used to explore the behavior of a Bragg structure with the ability to easily vary the important parameters such as refractive indices, number and thickness of layers.展开更多
Existence of out-of-plane conical dispersion for a triangular photonic crystal lattice is reported. It is observed that conical dispersion is maintained for a number of out-of-plane wave vectors(k_z). We study a case ...Existence of out-of-plane conical dispersion for a triangular photonic crystal lattice is reported. It is observed that conical dispersion is maintained for a number of out-of-plane wave vectors(k_z). We study a case where Dirac like linear dispersion exists but the photonic density of states is not vanishing, called Dwarf Dirac cone(DDC) which does not support localized modes. We demonstrate the trapping of such modes by introducing defects in the crystal. Interestingly, we find by k-point sampling as well as by tuning trapped frequency that such a conical dispersion has an inherent light confining property and it is governed by neither of the known wave confining mechanisms like total internal reflection, band gap guidance. Our study reveals that such a conical dispersion in a non-vanishing photonic density of states induces unexpected intense trapping of light compared with those at other points in the continuum. Such studies provoke fabrication of new devices with exciting properties and new functionalities.展开更多
The characteristics of the periodic band gaps of the one dimension magnetized plasma photonic crystals are studied with the piecewise linear current density recursive convolution (PLCDRC) finite-differential time-doma...The characteristics of the periodic band gaps of the one dimension magnetized plasma photonic crystals are studied with the piecewise linear current density recursive convolution (PLCDRC) finite-differential time-domain (FDTD) method. In frequency-domain, the transmission coefficients of electromagnetic Gaussian pulses are computed, and the effects of the periodic structure constant, plasma layer thickness and parameters of plasma on the properties of periodic band gaps of magnetized photonic crystals are analyzed. The results show that the periodic band gaps depend strongly on the plasma parameters.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 10975036 and 61071018)the Guangxi Natural Science Foundation,China (Grant No. 2010GXNSFB013049)
文摘This paper studies the dispersion characteristics of a modified photonic band-gap slow-wave structure with an open boundary by simulation and experiment.A mode launcher with a wheel radiator and a coupling probe is presented to excite a pure TM 01-like mode.The cold test and simulation results show that the TM 01-like mode is effectively excited and no parasitic modes appear.The dispersion characteristics obtained from the cold test are in good agreement with the calculated results.
基金Project supported by the National Key Basic Research Program of China (Grant No 2007CB31040)the National Natural Science Foundation of China (Grant No 60571020)
文摘This paper presents a three-dimensional particle-in-cell (PIC) simulation of a Ka-band relativistic Cherenkov source with a slow wave structure (SWS) consisting of metal photonic band gap (PBG) structures. In the simulation, a perfect match layer boundary is employed to absorb passing band modes supported by the PBG lattice with an artificial metal boundary. The simulated axial field distributions in the cross section and surface of the SWS demonstrate that the device operates in the vicinity of the π point of a TM01-like mode. The Fourier transformation spectra of the axial fields as functions of time and space show that only a single frequency appears at 36.27 GHz, which is in good agreement with that of the intersection of the dispersion curve with the slow space charge wave generated on the beam. The simulation results demonstrate that the SWS has good mode selectivity.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10674038 and 10604042)the National Basic Research Program of China (Grant No. 2006CB302901)
文摘This paper stuides numerically the model equation in a one dimensional defective photonic lattice by modifying the potential function to a periodic function. It is found that defect modes (DMs) can be regarded as Bloch modes which are excited from the extended photonic band-gap structure at Bloch wave-numbers with k x = 0. The DMs for both positive and negative defects are considered in this method.
基金the Shanghai Rising-Star Program(No.05QMX1459)the National Natural Science Foundation of China(No.60508018)
文摘Band structures of one-dimensional(1D)photonic crystals(PCs)containing dispersive left-handed meta- materials are studied theoretically.The results show that the structure possesses a type of photonic band gap originating from total internal reflection(TIR).In contrast to photonic band gaps corresponding to zero average refractive index and zero phase,the TIR gap exhibits sharp angular effect and has no po- larization effect.It should also be noted that band structures of transverse electric(TE)and transverse magnetic(TM)mode waves are exactly the same in the PCs we studied.
基金Project supported by the National Natural Science Foundations of China(Grant No.61275047)the Research Project of Chinese Ministry of Education(Grant No.213009A)the Scientific and Technological Development Foundation of Jilin Province,China(Grant No.20130101031JC)
文摘Two-dimensional function photonic crystals, in which the dielectric constants of medium columns are the functions of space coordinates , are proposed and studied numerically. The band gaps structures of the photonic crystals for TE and TM waves are different from the two-dimensional conventional photonic crystals. Some absolute band gaps and semiDirac points are found. When the medium column radius and the function form of the dielectric constant are modulated, the numbers, width, and position of band gaps are changed, and the semi-Dirac point can either occur or disappear. Therefore,the special band gaps structures and semi-Dirac points can be achieved through the modulation on the two-dimensional function photonic crystals. The results will provide a new design method of optical devices based on the two-dimensional function photonic crystals.
基金supported by the National Natural Science Foundation of China under Grant No. 60588502
文摘Two kinds of compact electromagnetic band gap (EBG) structures are designed.A two layer compact EBG structure configured with cross spiral shape line inductors and interdigital capacitors is first presented.Because of its significantly enlarged equivalent inductor and capacitance,the period of the lattice is approximately 4.5% of the free space wavelength.By insetting several narrow slits in the ground plane,the bandwidth of the main bandgap is enhanced by nearly 19%.Further effort has been made for designing a three layer compact EBG structure.Simulation results show that its period is reduced by about 26% compared to that of proposed two layer EBG structure,and the bandwidth of the main bandgap is about 3 times as that of the proposed two layer EBG structure.The detailed designs including a two layer compact 3×7 EBG array with and without defect ground plane and the three layer EBG array are given and simulation results are presented.
文摘Different feeding techniques of microstrip patch antennas with different spiral defected ground structures are presented in this paper. The investigated structures illustrate some merits in designing multi-electromagnetic band-gap structures by adjusting the capacitance and changing the inductance through varying the width and length of spiral defected ground structure. Then by applying the three different spirals shapes (one, two and four arms) as the ground plane of microstrip patch antenna with different feeding techniques to create multi or ultra wide-band, improve the antenna gain and reduce the antenna size, it is found that the four arms spiral defected ground structure of microstrip patch antenna with offset feed gives good performance, electrical size reduction to about 75% as compared to the original patch size and ultra-wide bandwidth extends from 2 GHz up to 12 GHz with ?8 dB impedance bandwidth.
文摘We show theoretically that range of reflection bands and defect modes inside the band gap can be tuned by using a one-dimensional tilted photonic crystal (TPC) structure. A TPC structure is similar to the conventional PC structure with the only difference that in this case alternate layers are inclined at certain angle in the direction of periodicity of the structure. In order to obtain the reflectance spectra of the proposed structure transfer matrix method (TMM) has been employed. From the analysis of the reflectance curve, it is found that 100% reflectance range can be varied and enhanced by using TPC structure for both (TE- and TM-) polarizations. The enhancement in reflection bands increases as the tilt angle increases for both the polarizations and hence the enlarged omni-reflectance bands are obtained. Further, we study the properties of the defect modes in TPC structure by introducing the tilted defect at the different tilt angle. The results show that defect modes (tunneling modes) can be tuned at different wavelengths by changing the tilt angle of the structure without changing other parameters. Finally, the effect of variation thickness of defect layers on the tunneling mode has been studied for both TPC and conventional PC structure. The proposed model might be used as a tunable broadband omnidirectional reflector as well as tunable tunneling or transmission mode, which has potential applications in the field of photonics and optoelectronics.
文摘Optical features of a semiconductor–dielectric photonic crystal are studied theoretically. Alternating layers of micrometer sized SiO2/In Sb slabs are considered as building blocks of the proposed ideal crystal. By inserting additional layers and disrupting the regularity, two more defective crystals are also proposed. Photonic band structure of the ideal crystal and its dependence on the structural parameters are explored at the first step. Transmittance of the defective crystals and its changes with the thicknesses of the layers are studied. After extracting the optimum values for the thicknesses of the unit cells of the crystals, the optical response of the proposed structures at different temperatures and incident angles are investigated. Changes of the defect layers’ induced mode(s) are discussed by taking into consideration of the temperature dependence of the In Sb layer permittivity. The results clearly reflect the high potential of the proposed crystals to be used at high temperature terahertz technology as a promising alternative to their electronic counterparts.
基金supported by the Special Foundation for Harb-in Young Scientists (Grant Number 2008RFQXG031)the Ba-sic Research Foundation of Harbin Engineering University.
文摘It is of great significance to present a photonic crystal lattice structure with a wide photonic bandgap. A two-dimension complex lattice photonic crystal is proposed. The photonic crystal is composed of complex lattices with triangular structure, and each single cell is surrounded by six scatterers in an hexagon. The photonic band gaps are calculated based on the plane wave expansion (PWE) method. The results indicate that the photonic crystal has tunable large TM polarization band gap, and a gap-midgap ratio of up to 45.6%.
基金Project supported by the National Natural Science Foundations of China(Grant Nos.11374107 and 10974061)
文摘In this paper, we investigate the optical transmission properties of perfect and defective two-segment-connected triangular waveguide networks(2SCTWNs) and find that after introducing defects in networks, many groups of transparent extreme narrow photonic passbands(ENPPs) will be created in the middle of the transmission spectra, the number for each group and the group number of ENPPs can be adjusted by the matching ratios of waveguide length(MRWLs), the number of defects, and the number of unit cells of 2SCTWNs. The influences of MRWL, number of defects, and number of unit cells on the number, width, and position of these ENPPs are researched and a series of quantitative rules and properties are obtained. It may be useful for the designing of high-sensitive optical switches, wavelength division multiplexers,extreme-narrowband filters, and other correlative waveguide network devices.
基金supported by the National Basic Research Program (973) under Grant No 2007CB31407
文摘Band gap characteristics of the photonic crystals in terahertz range with square lattice and triangular lattice of GaAs cylinders are comparatively studied by means of plane wave method (PWM). The influence of the radius on the band gap width is analyzed and the critical values where the band gap appears are put forward. The results show that the maximum band gap width of photonic crystal with triangular lattice of GaAs cylinders is much wider than that of photonic crystal with square lattice. The research provides a theoretic basis for the development of te rahertz (THz) devices.
文摘Knowledge of the band gap and transmission and reflection spectrum of a photonic crystal is essential elements for their design. A graphical interface that quickly determines the banding pattern and spectrum based on the Plane Wave Method (PWM) and coupled modes method (CMM) respectively is created. It is used to explore the behavior of a Bragg structure with the ability to easily vary the important parameters such as refractive indices, number and thickness of layers.
基金Supported by the National Basic Research Programme of China under Grant No 2006CB921701, the National Natural Science Foundation of China under Grant Nos 10634050 and 10704055, and the Shanghai Science and Technology Committee.
基金supported by Director,CSIR-CGCRI,the DST,Government of Indiathe CSIR 12th Plan Project(GLASSFIB),India
文摘Existence of out-of-plane conical dispersion for a triangular photonic crystal lattice is reported. It is observed that conical dispersion is maintained for a number of out-of-plane wave vectors(k_z). We study a case where Dirac like linear dispersion exists but the photonic density of states is not vanishing, called Dwarf Dirac cone(DDC) which does not support localized modes. We demonstrate the trapping of such modes by introducing defects in the crystal. Interestingly, we find by k-point sampling as well as by tuning trapped frequency that such a conical dispersion has an inherent light confining property and it is governed by neither of the known wave confining mechanisms like total internal reflection, band gap guidance. Our study reveals that such a conical dispersion in a non-vanishing photonic density of states induces unexpected intense trapping of light compared with those at other points in the continuum. Such studies provoke fabrication of new devices with exciting properties and new functionalities.
基金supported by the National Natural ScienceFoundation of China (Grant No. 60471002)
文摘The characteristics of the periodic band gaps of the one dimension magnetized plasma photonic crystals are studied with the piecewise linear current density recursive convolution (PLCDRC) finite-differential time-domain (FDTD) method. In frequency-domain, the transmission coefficients of electromagnetic Gaussian pulses are computed, and the effects of the periodic structure constant, plasma layer thickness and parameters of plasma on the properties of periodic band gaps of magnetized photonic crystals are analyzed. The results show that the periodic band gaps depend strongly on the plasma parameters.