The theoretical mechanism for realizing a negative refractive index material in an optical frequency range with an atomic gas system of electromagnetically induced transparency (EIT) is studied. It is shown that under...The theoretical mechanism for realizing a negative refractive index material in an optical frequency range with an atomic gas system of electromagnetically induced transparency (EIT) is studied. It is shown that under certain conditions such a dense gas can exhibit simultaneously negative permittivity and negative permeability, and negligibly small loss.展开更多
We propose a new class of negative refractive index transmission line in which ideal operational amplifiers are applied to form the periodically loaded negative-impedance-converted inductors and capacitors. The phase ...We propose a new class of negative refractive index transmission line in which ideal operational amplifiers are applied to form the periodically loaded negative-impedance-converted inductors and capacitors. The phase response of the new trans-mission line is opposite to that of a positive refractive index conventional transmission line. Unlike the existing negative refractive index transmission line,the new negative refractive index transmission line is non-dispersive and thus can lead to many novel applications such as designing new broadband devices.展开更多
By means of the theory of electromagnetic wave propagation and transfer matrix method, this paper investigates the band rules for the frequency spectra of three kinds of one-dimensional （1D） aperiodic photonic cryst...By means of the theory of electromagnetic wave propagation and transfer matrix method, this paper investigates the band rules for the frequency spectra of three kinds of one-dimensional （1D） aperiodic photonic crystals （PCs）, generalized Fibonacci GF（p, 1）, GF（1,2）, and Thue Morse （TM） PCs, with negative refractive index （NRI） materials. It is found that all of these PCs can open a broad zero-n gap, TM PC possesses the largest zero-n gap, and with the increase of p, the width of the zero-n gap for GF（p, 1） PC becomes smaller. This characteristic is caused by the symmetry of the system and the open position of the zero-n gap. It is found that for GF（p, 1） PCs, the possible limit zero-n gaps open at lower frequencies with the increase of p, but for GF（1,2） and TM PCs, their limit zero-n gaps open at the same frequency. Additionally, for the tbree bottom-bands, we find the interesting perfect self-similarities of the evolution structures with the increase of generation, and obtain the corresponding subband-number formulae. Based on 11 types of evolving manners Qi （i = 1, 2,... , 11） one can plot out the detailed evolution structures of the three kinds of aperiodic PCs for any generation.展开更多
A closed four-level system in atomic vapour is proposed, which is made to possess left handedness by using the technique of quantum coherence. The density matrix method is utilized in view of the rotating-wave approxi...A closed four-level system in atomic vapour is proposed, which is made to possess left handedness by using the technique of quantum coherence. The density matrix method is utilized in view of the rotating-wave approximation and the effect of a local field in dense gas. The numerical simulation result shows that the negative permittivity and the negative permeability of the medium can be achieved simultaneously （i.e. the left handedness） in a wider frequency band under appropriate parameter conditions. Furthermore, when analysing the dispersion property of the left-handed material, we can find that the probe beam propagation can be controlled from superluminal to subluminal, or vice versa via changing the detuning of the probe field.展开更多
In this letter,we introduce a novel passive transmission line of negative refractive index(i.e.,left-handedness)based on identical symmetrical lattice type structures thus called "lattice type transmission line&q...In this letter,we introduce a novel passive transmission line of negative refractive index(i.e.,left-handedness)based on identical symmetrical lattice type structures thus called "lattice type transmission line"(LT-TL).The dispersion characteristic and the transmission response of the proposed LT-TL are analyzed.While all the other left-handed passive transmission lines are of high pass,the present passive left-handed transmission line is of low pass.Compared with a conventional transmission line,the LT-TL has a phase shift of 180° in the entire wide pass-band.展开更多
Transmission and negative refractive index （NRI） of metal-dielectric-metal （MDM） sandwiched metamaterial perfo- rated with four kinds of shapes of holes are numerically studied. Results indicate that positions of ...Transmission and negative refractive index （NRI） of metal-dielectric-metal （MDM） sandwiched metamaterial perfo- rated with four kinds of shapes of holes are numerically studied. Results indicate that positions of all transmission peaks of these kinds of holes are sensitive to the shape of the hole. Under the same conditions, the circular hole can obtain the maximum NRI and the rectangular hole can obtain the maximum frequency bandwidth of NRI. Moreover, the figure of merit （FOM） of the circular hole is the maximum too. As a result, we can obtain a higher NRI and FOM metamaterial by drilling circular hole arrays on MDM metamaterial.展开更多
A new structure containing negative refractive index dielectric layer（NRlDL） is introduced into microcavity. The properties of the new mierocavity organic light-emitting devices（MOLEDs） are investigated. In the ex...A new structure containing negative refractive index dielectric layer（NRlDL） is introduced into microcavity. The properties of the new mierocavity organic light-emitting devices（MOLEDs） are investigated. In the experiment, the transfer matrix method is adopted. The dependence of reflectance and transmittance on the refractive index and thickness of NRIDL are analyzed in detail. Compared with the electroluminescence spectra of non-NRIDL diodes, the line widths of the spectra of the MOLEDs are narrower and all the peaks enhance. The results show that the new structure is beneficial to improve the performance and reduce the thickness of microcavity devices.展开更多
The transmission and negative refractive index(NRI) of metal–dielectric–metal sandwiched metamaterials perforated with di?erent filling media of holes are numerically studied. Results indicate that filling the appro...The transmission and negative refractive index(NRI) of metal–dielectric–metal sandwiched metamaterials perforated with di?erent filling media of holes are numerically studied. Results indicate that filling the appropriate medium in rectangular holes can enhance transmission. The NRI and frequency bandwidth of NRI decrease with increased relative permittivity of the filling medium. A stronger magnetic response that contributes to the dual NRI metamaterials is found.展开更多
We show that dielectric waveguides formed by materials with strong optical anisotropy support electromagnetic waves that combine the properties of propagating and evanescent fields.These“ghost waves”are created in t...We show that dielectric waveguides formed by materials with strong optical anisotropy support electromagnetic waves that combine the properties of propagating and evanescent fields.These“ghost waves”are created in tangent bifurcations that“annihilate”pairs of positive-and negative-index modes and represent the optical analogue of the“ghost orbits”in the quantum theory of nonintegrable dynamical systems.Ghost waves can be resonantly coupled to the incident evanescent field,which then grows exponentially through the anisotropic media—as in the case of negative index materials.As ghost waves are supported by transparent dielectric media,the proposed approach to electromagnetic field enhancement is free from the“curse”of material loss that is inherent to conventional negative index composites.展开更多
Bistability behaviors in an optical ring cavity filled with a dense V-type four-level atomic medium are theoretically investigated. It is found that the optical bistability can appear in the negative refraction freque...Bistability behaviors in an optical ring cavity filled with a dense V-type four-level atomic medium are theoretically investigated. It is found that the optical bistability can appear in the negative refraction frequency band, while both the bistability and multi-stability can occur in the positive refraction frequency bands. Therefore, optical bistability can be realized from conventional material to negative index material due to quantum coherence in our scheme.展开更多
Metamaterial structure based on cascaded split ring resonators (CSRR) is proposed in order to produce a negative refractive index in terahertz regime at near-infrared range. We have incident light horizontally instead...Metamaterial structure based on cascaded split ring resonators (CSRR) is proposed in order to produce a negative refractive index in terahertz regime at near-infrared range. We have incident light horizontally instead of incidenting it perpendicular. We have measured the negative refractive index, permeability and permittivity by using the S-parameter analysis. Furthermore, it is found out that negative refractive index, permeability and permittivity are dependent upon the width of the wire and the gap between resonators at near-infrared range. This work will be helpful for the fabrication and design of double negative metamaterials structure having negative permeability, permittivity and negative refractive index for in plane applications.展开更多
The refraction index of the quantized lossy composite right-left handed transmission line（CRLH-TL） is deduced in the thermal coherence state. The results show that the negative refraction index（herein the left-hand...The refraction index of the quantized lossy composite right-left handed transmission line（CRLH-TL） is deduced in the thermal coherence state. The results show that the negative refraction index（herein the left-handedness） can be implemented by the electric circuit dissipative factors（i.e., the resistances R and conductances G） in a higher frequency band（1.446 GHz≤ ω ≤ 15 GHz）, and flexibly adjusted by the left-handed circuit components（Cl, Ll） and the right-handed circuit components（Cr, Lr） at a lower frequency（ω = 0.995 GHz）. The flexible adjustment for left-handedness in a wider bandwidth will be significant for the microscale circuit design of the CRLH-TL and may make the theoretical preparation for its compact applications.展开更多
An effective method to design structural Left-handed material（LHM） was proposed. A commercial finite element software HFSS and S-parameter retrieval method were used to determine the effective constitutive parameter...An effective method to design structural Left-handed material（LHM） was proposed. A commercial finite element software HFSS and S-parameter retrieval method were used to determine the effective constitutive parameters of the metamaterials, and topology optimization technique was introduced to design the microstructure configurations of the materials with desired electromagnetic characteristics. The material considered was a periodic array of dielectric substrates attached with metal film pieces. By controlling the arrangements of the metal film pieces in the design domain, the potential microstructure with desired electromagnetic characteristics can be obtained finally. Two different LHMs were obtained with maximum bandwidth of negative refraction, and the experimental results show that negative refractive indices appear while the metamaterials have simultaneously negative permittivity and negative permeability. Topology optimization technique is found to be an effective tool for configuration design of LHMs.展开更多
A broadband negative refractive index metamaterial based on a windmill-like structure is proposed, and investigated numerically and experimentally at the microwave frequency range. From the numerical and experimental ...A broadband negative refractive index metamaterial based on a windmill-like structure is proposed, and investigated numerically and experimentally at the microwave frequency range. From the numerical and experimental results, effect media parameters are retrieved, which clearly show that two broad frequency bands exist in which the permittivity and permeability are negative. The two negative bands are from 9.1 GHz to 10.5 GHz and from 12.05 GHz to 14.65 GHz respectively, and the negative bandwidth is 4 GHz. Due to the good bandwidth performance, the metallic cell with double negative property obtained in this paper is suitable for use in the design of multiband or broadband microwave devices.展开更多
In this paper we have investigated three external fields interacting with the four-level Y-type atomic system described by the density-matrix approach. The results show that left-handedness with zero absorption is ach...In this paper we have investigated three external fields interacting with the four-level Y-type atomic system described by the density-matrix approach. The results show that left-handedness with zero absorption is achieved. The zero absorption property displays the possibility of manipulation by varying the phase and the intensity of the coupling field. Also, the zero absorption property may be used to amplify the evanescent waves that have been lost in imaging by traditional lenses. We propose an approach to obtain a negative refractive medium with zero absorption and the possibility of enhaneeingthe imaging resolution in realizing ＇superlenses＇.展开更多
A low absorptivity broadband negative refractive index metamaterial with a multi-gap split-ring and metallic cross （MSMC） structure is proposed and investigated numerically and experimentally in the microwave freque...A low absorptivity broadband negative refractive index metamaterial with a multi-gap split-ring and metallic cross （MSMC） structure is proposed and investigated numerically and experimentally in the microwave frequency range. The effective media parameters were retrieved from the numerical and experimental results, which clearly show that there exists a very wide frequency band where the permittivity and permeability are negative. The influence of the structure parameters on the magnetic response and the cut-off frequency of the negative permittivity are studied in detail. This metamaterial would have potential application in designing broadband microwave devices.展开更多
A method to realize absolute negative refraction index -1 with a two-dimensional （2D） photonic crystal is presented by introducing dielectric anisotropy in the photonic crystal material. The band structures of E-pol...A method to realize absolute negative refraction index -1 with a two-dimensional （2D） photonic crystal is presented by introducing dielectric anisotropy in the photonic crystal material. The band structures of E-polarization mode and H-polarization mode can be adjusted by changing the parameters of materials. Thus the two modes with different polarizations have the same negative refraction index -1 for the same frequency. The results are demonstrated by numerical simulation based on the finite-difference time-domain （FDTD） method.展开更多
A completely open cavity, which is formed by three 60-degree wedges of a photonic crystal with negative effective index, is introduced. Such a realizable design for a completely open cavity (i.e., without any reflecti...A completely open cavity, which is formed by three 60-degree wedges of a photonic crystal with negative effective index, is introduced. Such a realizable design for a completely open cavity (i.e., without any reflective wall in the radial direction) is the first of its kind ever been reported. Due to the negative effective refraction index of the photonic crystal and the high transmission at the photonic crystal/air interfaces, a closed path with zero optical path is formed for the resonance. The present open cavity is very suitable for use as a biosensor as it has large air wedges into which a liquid measurand can flow easily.展开更多
The effective optical constants that describe the interaction between electromagnetic wave and particulate composite are calculated based on effective medium theory and Mie theory.The negative refractive phenomenon is...The effective optical constants that describe the interaction between electromagnetic wave and particulate composite are calculated based on effective medium theory and Mie theory.The negative refractive phenomenon is compared between the Ge-particle-dispersed LiTaO 3 composites and Ag-particle-dispersed LiTaO 3 composites.It is indicated that the negative refraction phenomenon for semiconductor Ge particulate composite occurs in higher frequency range than that of noble Ag particulate composite.By take the Ge particulate composite as an example,the influence of size and number density of spherical particles on the negative refraction phenomenon is analyzed.It is indicated that the frequency range where negative refraction phenomenon occurs can be shifted to higher frequency by adjusting these two influencing factors.展开更多
This article designs a novel type of non-bravais lattice photonic crystal fiber.To form the nesting complexperiod with positive and negative refractive index materials respectively,a cylinder with the same radius and ...This article designs a novel type of non-bravais lattice photonic crystal fiber.To form the nesting complexperiod with positive and negative refractive index materials respectively,a cylinder with the same radius and negative refractive index is introduced into the center of each lattice unit cell in the traditional square lattice air-holes photonic crystal fiber.The photonic band-gap of the photonic crystal fiber is calculated numerically by the plane wave expansion method.The result shows that compared with the traditional square photonic band-gap fiber(PBGF),when R=Λis 0.35,the refractive index of the substrate,airhole,and medium-column are 1.30,1.0,and–1:0,respectively.This new PBGF can transmit signal by the photonic band-gap effect.When the lattice constantΛvaries from 1:5μm to 3:0μm,the range of the wavelength ranges from 880 nm to 2300 nm.展开更多
基金Project supported by the National Natural Science Foundation(NSF) of China (Nos. 90101024 and 60378037) and the NationalBasic Research Program (973) of China (No. 2004CB719805)
文摘The theoretical mechanism for realizing a negative refractive index material in an optical frequency range with an atomic gas system of electromagnetically induced transparency (EIT) is studied. It is shown that under certain conditions such a dense gas can exhibit simultaneously negative permittivity and negative permeability, and negligibly small loss.
基金Project supported by the National Basic Research Program (973) of China (No. 2004CB719802)the National Natural Science Foundation of China (No. 60378037)
文摘We propose a new class of negative refractive index transmission line in which ideal operational amplifiers are applied to form the periodically loaded negative-impedance-converted inductors and capacitors. The phase response of the new trans-mission line is opposite to that of a positive refractive index conventional transmission line. Unlike the existing negative refractive index transmission line,the new negative refractive index transmission line is non-dispersive and thus can lead to many novel applications such as designing new broadband devices.
基金Project supported by the National Natural Science Foundation of China (Grant No 10974061)the Program for Innovative Research Team of the Higher Education of Guangdong Province of China (Grant No 06CXTD005)
文摘By means of the theory of electromagnetic wave propagation and transfer matrix method, this paper investigates the band rules for the frequency spectra of three kinds of one-dimensional （1D） aperiodic photonic crystals （PCs）, generalized Fibonacci GF（p, 1）, GF（1,2）, and Thue Morse （TM） PCs, with negative refractive index （NRI） materials. It is found that all of these PCs can open a broad zero-n gap, TM PC possesses the largest zero-n gap, and with the increase of p, the width of the zero-n gap for GF（p, 1） PC becomes smaller. This characteristic is caused by the symmetry of the system and the open position of the zero-n gap. It is found that for GF（p, 1） PCs, the possible limit zero-n gaps open at lower frequencies with the increase of p, but for GF（1,2） and TM PCs, their limit zero-n gaps open at the same frequency. Additionally, for the tbree bottom-bands, we find the interesting perfect self-similarities of the evolution structures with the increase of generation, and obtain the corresponding subband-number formulae. Based on 11 types of evolving manners Qi （i = 1, 2,... , 11） one can plot out the detailed evolution structures of the three kinds of aperiodic PCs for any generation.
基金supported by the National Natural Science Foundation of China (Grant Nos. 60768001 and 10464002)
文摘A closed four-level system in atomic vapour is proposed, which is made to possess left handedness by using the technique of quantum coherence. The density matrix method is utilized in view of the rotating-wave approximation and the effect of a local field in dense gas. The numerical simulation result shows that the negative permittivity and the negative permeability of the medium can be achieved simultaneously （i.e. the left handedness） in a wider frequency band under appropriate parameter conditions. Furthermore, when analysing the dispersion property of the left-handed material, we can find that the probe beam propagation can be controlled from superluminal to subluminal, or vice versa via changing the detuning of the probe field.
基金Project supported by the National Basic Research Program (973) of China (No. 2004CB719802)the Natural Science Foundation ofZhejiang Province (No. R104154),China
文摘In this letter,we introduce a novel passive transmission line of negative refractive index(i.e.,left-handedness)based on identical symmetrical lattice type structures thus called "lattice type transmission line"(LT-TL).The dispersion characteristic and the transmission response of the proposed LT-TL are analyzed.While all the other left-handed passive transmission lines are of high pass,the present passive left-handed transmission line is of low pass.Compared with a conventional transmission line,the LT-TL has a phase shift of 180° in the entire wide pass-band.
基金Project supported partially by the National Natural Science Foundation of China (Grant No.60778041)the Natural Science Foundation of the Jiangsu Higher Education Institutions,China (Grant No.07KJA51001)
文摘Transmission and negative refractive index （NRI） of metal-dielectric-metal （MDM） sandwiched metamaterial perfo- rated with four kinds of shapes of holes are numerically studied. Results indicate that positions of all transmission peaks of these kinds of holes are sensitive to the shape of the hole. Under the same conditions, the circular hole can obtain the maximum NRI and the rectangular hole can obtain the maximum frequency bandwidth of NRI. Moreover, the figure of merit （FOM） of the circular hole is the maximum too. As a result, we can obtain a higher NRI and FOM metamaterial by drilling circular hole arrays on MDM metamaterial.
基金Natural Science Research Item of Education Department of Henan Province(2008A430009)Doctor Foundation of Henan Polytechnic University(B2008-22)
文摘A new structure containing negative refractive index dielectric layer（NRlDL） is introduced into microcavity. The properties of the new mierocavity organic light-emitting devices（MOLEDs） are investigated. In the experiment, the transfer matrix method is adopted. The dependence of reflectance and transmittance on the refractive index and thickness of NRIDL are analyzed in detail. Compared with the electroluminescence spectra of non-NRIDL diodes, the line widths of the spectra of the MOLEDs are narrower and all the peaks enhance. The results show that the new structure is beneficial to improve the performance and reduce the thickness of microcavity devices.
基金supported by the National Natural Science Foundation of China(No.60778041)the Graduate Education Innovation Project of Jiangsu Province(No.CXLX13_39)
文摘The transmission and negative refractive index(NRI) of metal–dielectric–metal sandwiched metamaterials perforated with di?erent filling media of holes are numerically studied. Results indicate that filling the appropriate medium in rectangular holes can enhance transmission. The NRI and frequency bandwidth of NRI decrease with increased relative permittivity of the filling medium. A stronger magnetic response that contributes to the dual NRI metamaterials is found.
基金This work was partially supported by the National Science Foundation(Grant No.DMREF-1629276)Army Research Office(Grant No.W911NF-14-1-0639),and Gordon and Betty Moore Foundation.
文摘We show that dielectric waveguides formed by materials with strong optical anisotropy support electromagnetic waves that combine the properties of propagating and evanescent fields.These“ghost waves”are created in tangent bifurcations that“annihilate”pairs of positive-and negative-index modes and represent the optical analogue of the“ghost orbits”in the quantum theory of nonintegrable dynamical systems.Ghost waves can be resonantly coupled to the incident evanescent field,which then grows exponentially through the anisotropic media—as in the case of negative index materials.As ghost waves are supported by transparent dielectric media,the proposed approach to electromagnetic field enhancement is free from the“curse”of material loss that is inherent to conventional negative index composites.
基金Project supported by the Fundamental Research Funds for the Central University (Grant Nos.GK201002024 and GK201003003)the National Natural Science Foundation of China (Grant Nos.11104176 and 11104185)+2 种基金the Natural Science Foundation of Shaanxi Province,China (Grant No.2011JQ1008)the Special Fund of Shanghai Outstanding Young Teachers,China (Grant Nos.slg10054 and slg10023)the Innovation Program of Shanghai Municipal Education Commission,China (Grant No.11YZ118)
文摘Bistability behaviors in an optical ring cavity filled with a dense V-type four-level atomic medium are theoretically investigated. It is found that the optical bistability can appear in the negative refraction frequency band, while both the bistability and multi-stability can occur in the positive refraction frequency bands. Therefore, optical bistability can be realized from conventional material to negative index material due to quantum coherence in our scheme.
文摘Metamaterial structure based on cascaded split ring resonators (CSRR) is proposed in order to produce a negative refractive index in terahertz regime at near-infrared range. We have incident light horizontally instead of incidenting it perpendicular. We have measured the negative refractive index, permeability and permittivity by using the S-parameter analysis. Furthermore, it is found out that negative refractive index, permeability and permittivity are dependent upon the width of the wire and the gap between resonators at near-infrared range. This work will be helpful for the fabrication and design of double negative metamaterials structure having negative permeability, permittivity and negative refractive index for in plane applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.61205205 and 6156508508)the General Program of Yunnan Provincial Applied Basic Research Project,China(Grant No.2016FB009)the Foundation for Personnel Training Projects of Yunnan Province,China(Grant No.KKSY201207068)
文摘The refraction index of the quantized lossy composite right-left handed transmission line（CRLH-TL） is deduced in the thermal coherence state. The results show that the negative refraction index（herein the left-handedness） can be implemented by the electric circuit dissipative factors（i.e., the resistances R and conductances G） in a higher frequency band（1.446 GHz≤ ω ≤ 15 GHz）, and flexibly adjusted by the left-handed circuit components（Cl, Ll） and the right-handed circuit components（Cr, Lr） at a lower frequency（ω = 0.995 GHz）. The flexible adjustment for left-handedness in a wider bandwidth will be significant for the microscale circuit design of the CRLH-TL and may make the theoretical preparation for its compact applications.
基金Funded by the National Natural Science Foundation of China (Nos.90605002, 90816025 and 10721062)the National Basic Research Programof China (No. 2006CB601205)
文摘An effective method to design structural Left-handed material（LHM） was proposed. A commercial finite element software HFSS and S-parameter retrieval method were used to determine the effective constitutive parameters of the metamaterials, and topology optimization technique was introduced to design the microstructure configurations of the materials with desired electromagnetic characteristics. The material considered was a periodic array of dielectric substrates attached with metal film pieces. By controlling the arrangements of the metal film pieces in the design domain, the potential microstructure with desired electromagnetic characteristics can be obtained finally. Two different LHMs were obtained with maximum bandwidth of negative refraction, and the experimental results show that negative refractive indices appear while the metamaterials have simultaneously negative permittivity and negative permeability. Topology optimization technique is found to be an effective tool for configuration design of LHMs.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61172115 and 60872029)the National High-Technology Research and Development Program of China (Grant No. 2008AA01Z206)+1 种基金the Aeronautics Foundation of China (Grant No. 20100180003)the Fundamental Research Funds for the Central Universities, China (Grant No. ZYGX 2009J037)
文摘A broadband negative refractive index metamaterial based on a windmill-like structure is proposed, and investigated numerically and experimentally at the microwave frequency range. From the numerical and experimental results, effect media parameters are retrieved, which clearly show that two broad frequency bands exist in which the permittivity and permeability are negative. The two negative bands are from 9.1 GHz to 10.5 GHz and from 12.05 GHz to 14.65 GHz respectively, and the negative bandwidth is 4 GHz. Due to the good bandwidth performance, the metallic cell with double negative property obtained in this paper is suitable for use in the design of multiband or broadband microwave devices.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60768001 and 10464002)
文摘In this paper we have investigated three external fields interacting with the four-level Y-type atomic system described by the density-matrix approach. The results show that left-handedness with zero absorption is achieved. The zero absorption property displays the possibility of manipulation by varying the phase and the intensity of the coupling field. Also, the zero absorption property may be used to amplify the evanescent waves that have been lost in imaging by traditional lenses. We propose an approach to obtain a negative refractive medium with zero absorption and the possibility of enhaneeingthe imaging resolution in realizing ＇superlenses＇.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61172115 and 60872029)the High-Tech Research and Development Program of China (Grant No. 2008AA01Z206)+1 种基金the Aeronautics Foundation of China (Grant No. 20100180003)the Fundamental Research Funds for the Central Universities of China (Grant No. ZYGX 2009J037)
文摘A low absorptivity broadband negative refractive index metamaterial with a multi-gap split-ring and metallic cross （MSMC） structure is proposed and investigated numerically and experimentally in the microwave frequency range. The effective media parameters were retrieved from the numerical and experimental results, which clearly show that there exists a very wide frequency band where the permittivity and permeability are negative. The influence of the structure parameters on the magnetic response and the cut-off frequency of the negative permittivity are studied in detail. This metamaterial would have potential application in designing broadband microwave devices.
基金This work was supported by the National Natural Science Foundation of China(No.60471047)the Natural Science Foundation of Guangdong Province(No.04011308)the Shenzhen Bureau of Science and Technology
文摘A method to realize absolute negative refraction index -1 with a two-dimensional （2D） photonic crystal is presented by introducing dielectric anisotropy in the photonic crystal material. The band structures of E-polarization mode and H-polarization mode can be adjusted by changing the parameters of materials. Thus the two modes with different polarizations have the same negative refraction index -1 for the same frequency. The results are demonstrated by numerical simulation based on the finite-difference time-domain （FDTD） method.
基金Project supported by the National Basic Research Program (973) of China (No. 2004CB719801), and the National Natural Science Foun-dation of China (Nos. 90101024 and 60378037)
文摘A completely open cavity, which is formed by three 60-degree wedges of a photonic crystal with negative effective index, is introduced. Such a realizable design for a completely open cavity (i.e., without any reflective wall in the radial direction) is the first of its kind ever been reported. Due to the negative effective refraction index of the photonic crystal and the high transmission at the photonic crystal/air interfaces, a closed path with zero optical path is formed for the resonance. The present open cavity is very suitable for use as a biosensor as it has large air wedges into which a liquid measurand can flow easily.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50936002 and 51006053)
文摘The effective optical constants that describe the interaction between electromagnetic wave and particulate composite are calculated based on effective medium theory and Mie theory.The negative refractive phenomenon is compared between the Ge-particle-dispersed LiTaO 3 composites and Ag-particle-dispersed LiTaO 3 composites.It is indicated that the negative refraction phenomenon for semiconductor Ge particulate composite occurs in higher frequency range than that of noble Ag particulate composite.By take the Ge particulate composite as an example,the influence of size and number density of spherical particles on the negative refraction phenomenon is analyzed.It is indicated that the frequency range where negative refraction phenomenon occurs can be shifted to higher frequency by adjusting these two influencing factors.
文摘This article designs a novel type of non-bravais lattice photonic crystal fiber.To form the nesting complexperiod with positive and negative refractive index materials respectively,a cylinder with the same radius and negative refractive index is introduced into the center of each lattice unit cell in the traditional square lattice air-holes photonic crystal fiber.The photonic band-gap of the photonic crystal fiber is calculated numerically by the plane wave expansion method.The result shows that compared with the traditional square photonic band-gap fiber(PBGF),when R=Λis 0.35,the refractive index of the substrate,airhole,and medium-column are 1.30,1.0,and–1:0,respectively.This new PBGF can transmit signal by the photonic band-gap effect.When the lattice constantΛvaries from 1:5μm to 3:0μm,the range of the wavelength ranges from 880 nm to 2300 nm.
