Archimedean photonic crystal has become a research area of great interest due to its various unique properties. Here, we experimentally demonstrate the realization of reconfigurable(4, 6^(2))and(4, 8^(2)) Archimedean ...Archimedean photonic crystal has become a research area of great interest due to its various unique properties. Here, we experimentally demonstrate the realization of reconfigurable(4, 6^(2))and(4, 8^(2)) Archimedean plasma photonic crystals(APPCs) by use of dielectric barrier discharges in air. Dynamical control on both the macrostructures including the lattice symmetry and the crystal orientation, and the microstructures including the fine structures of scattering elements has been achieved. The formation mechanisms of APPCs are studied by time-resolved measurements together with numerical simulations. Large omnidirectional band gaps of APPCs have been obtained. The tunable topology of APPCs may offer new opportunities for fabricating multi-functional and highly-integrated microwave devices.展开更多
We present a both theoretical and experimental investigation into the effect of array periodicity on the filtering characteristics of metal/dielectric photonic crystals(MDPhCs) with hexagonal arrays of subwavelength...We present a both theoretical and experimental investigation into the effect of array periodicity on the filtering characteristics of metal/dielectric photonic crystals(MDPhCs) with hexagonal arrays of subwavelength holes in gold/silicon dioxide films,varying the array periodicity from 6 to 8μm every 1μm while the ratio of hole radius to array periodicity is kept constant(1/4).The results indicate that the reflectance spectrum is highly dependent on the array periodicity.When the array periodicity increases,the reflectance spectrum exhibits a large redshift regularly.The finite difference time domain(FDTD) simulations agree well with the experimental results. By analyzing the relationship between the position of the reflectance minimum and the array periodicity,we find that the filtering characteristics of MDPhCs have an almost linear relationship with the array periodicity under the conditions of keeping the same ratio of hole radius to array periodicity(1/4).This finding provides an effective way to control the filtering characteristics of MDPhCs,which have potential applications in optical filters,plasmonic thermal emitters and so on.展开更多
We report five types of patterns with square symmetry,including three novel types obtained by inserting a specially designed grid photonic crystal(PC)into a dielectric barrier discharge system.They are studied using a...We report five types of patterns with square symmetry,including three novel types obtained by inserting a specially designed grid photonic crystal(PC)into a dielectric barrier discharge system.They are studied using an intensified charge-coupled device camera and photomultiplier tubes.The three novel types of patterns are a square pattern with one structure,a square superlattice pattern with four sublattices and a(1/4)K_(grid)(K_(grid)is the basic wave vector of the grid),and another square pattern with a complex inversion discharge sequence.From the application viewpoint,the five types of patterns can be used as plasma photonic crystals(PPCs).Their band diagrams under a transverse-magnetic wave simulated by the finite element method show that there are a large number of band gaps.Compared with the original PC with only a unidirectional band gap,the five types of PPCs have tunable and omnidirectional band gaps,which is very important in controlling the propagation of electromagnetic waves in the mm-wave region.The experimental results enrich the pattern types in the dielectric barrier discharge system and provide a method for obtaining PPCs with symmetry controllability and bandgap tunability.展开更多
The optical transmission properties of two types of photonic crystals have been analyzed by using the transfer matrix method. The first one is the dielectric photonic crystal (DPC), and the second is the metallic phot...The optical transmission properties of two types of photonic crystals have been analyzed by using the transfer matrix method. The first one is the dielectric photonic crystal (DPC), and the second is the metallic photonic crystal (MPC). We found the dielectric and metallic photonic crystals have different transmission spectra. The effect of the most prameters on the transmission spectra of the dielectric and metallic photonic crystals has been studied.展开更多
This paper has theoretically studied the characteristic frequencies of band structures in two-dimensional metallic- dielectric photonic crystals. It is demonstrated that a large filling fraction benefits the existence...This paper has theoretically studied the characteristic frequencies of band structures in two-dimensional metallic- dielectric photonic crystals. It is demonstrated that a large filling fraction benefits the existence of absolute photonic band gap, while a smaller filling fraction benefits an absolute negative refraction band. In addition, it also finds that the relation between the cut-off frequency of E-polarized wave and the filling fraction exceeding 10% is content with a linear increasing function, whose coefficients are exponential to the normalized lattice constant. These investigations have significant implications for tuning the operational frequencies to desired applications and manufacturing photonic crystals.展开更多
A novel one-dimensional plasma photonic crystal whose crystal orientation can change spontaneously is demonstrated using a dielectric barrier discharge with two liquid electrodes. The orientation of the plasma photoni...A novel one-dimensional plasma photonic crystal whose crystal orientation can change spontaneously is demonstrated using a dielectric barrier discharge with two liquid electrodes. The orientation of the plasma photonic crystal will vary from transverse to longitudinal or vary from longitudinal to transverse and then revert to longitudinal by self-adjustment, while the experimental conditions are kept fixed. The dispersion relation of these plasma photonic crystals are calculated, and the changes of the photonic band diagrams during the orientation transition are studied.展开更多
A two-dimensional photonic crystal with a one-dimensional periodic dielectric background is proposed. The photonic band modulation effects due to the periodic background are investigated based on the plane wave expans...A two-dimensional photonic crystal with a one-dimensional periodic dielectric background is proposed. The photonic band modulation effects due to the periodic background are investigated based on the plane wave expansion method. We find that periodic modulation of the dielectric background greatly alters photonic band structures, especially for the E-polarization modes. The number, width and position of the photonic band gaps (PBGs) sensitively depend on the structure parameters (the layer thicknesses and dielectric constants) of the one-dimensional periodic background,展开更多
The characteristics of photonic forbidden bands, transmission gain and absorption of one-dimensional (ID) dual-periodical photonic crystals (PC) with a complex dielectric layer were studied by using the optical tr...The characteristics of photonic forbidden bands, transmission gain and absorption of one-dimensional (ID) dual-periodical photonic crystals (PC) with a complex dielectric layer were studied by using the optical transfer matrix (TM) method. The results show that the photonic band gap (PBG) of this structure is enlarged and many transmission resonance peaks appear in PBG. Large transmission gain for transmission peaks is obtained if the imaginary part of dielectric constant is negative. With the increase of the absolute value of the imaginary part, the transmission gain increases firstly and the transmittance gain gets to an apex. The imaginary parts of dielectric constant corresponding to transmission gain apex are different according to wavelength. However, the transmission ratio of resonance peaks is less than 1 if the imagi- nary part of dielectric constant is positive. The properties might be used to design multi-narrow-channel band filters and optical amplification devices synchronously.展开更多
The features of the band structures of woodpile three-dimensional (3D) photonic crystals composed of plasma and function dielectric constituents, referred to as function plasma photonic crystals (FPPCs), are theor...The features of the band structures of woodpile three-dimensional (3D) photonic crystals composed of plasma and function dielectric constituents, referred to as function plasma photonic crystals (FPPCs), are theoretically studied by a modified plane wave expansion method, and the formulas for computing the band structures are derived. The arrangement for the proposed FPPCs is that the function dielectric columns are surrounded by plasma, and the embedded dielectric columns are stacked according to the woodpile lattices, which are arrayed with facecentered-tetragonal symmetry. The relative permittivity of function dielectric rods depends on the function coefficient and space coordinates. The relationships between the parameters for inserted function dielectric rods and plasma and the band structures are also investigated. The computed results illustrate that the obtained PBG can be tuned by those parameters as mentioned above. Compared to dielectric-air PCs, function dielectric PCs and plasma dielectric PCs with the same topology, a wider bandwidth of the photonic band gap can be observed in the proposed FPPCs. The calculated results also show us another alternative way to realize reconfigurable applications with 3D FPPCs.展开更多
Using the rigorous multiple-scattering theory, we study the dispersion relation of electromagnetic (EM) waves in two dimensional dielectric photonic crystals (PCs) and metallic photonic crystals (MPCs) in the lo...Using the rigorous multiple-scattering theory, we study the dispersion relation of electromagnetic (EM) waves in two dimensional dielectric photonic crystals (PCs) and metallic photonic crystals (MPCs) in the low-frequency limit. Analytic formula for the effective velocity of EM waves in PCs and MPCs is obtained. Accuracy of our formula is checked by comparing the results with rigorous calculations. For PCs, our result is exactly the same as the coherent potential approximation (CPA), which is accurate even when the filling fraction is high. But for MPCs, our approach demonstrates special advantages, while the CPA theory fails, in predicting the effective velocity of EM waves in MPCs at low frequency.展开更多
The transfer matrix method is used to study the effect of the permittivity profile on the reflectivity of a one dimensional plasma photonic crystal having exponentially graded material. The analysis shows that the pro...The transfer matrix method is used to study the effect of the permittivity profile on the reflectivity of a one dimensional plasma photonic crystal having exponentially graded material. The analysis shows that the proposed structure works as a perfect mirror within a certain frequency range. These frequency ranges can be completely controlled by the permittivity profile of a graded dielectric layer. As expected we observed that these frequency ranges are also controlled by plasma parameters.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
Application of the pressure controlled isothermal heating vertical deposition method to the fabrication of colloidal photonic crystals is systematically investigated in this paper. The fabricated samples are character...Application of the pressure controlled isothermal heating vertical deposition method to the fabrication of colloidal photonic crystals is systematically investigated in this paper. The fabricated samples are characterized by scanning electron microscope and transmission spectrum. High-quality samples with large transmissions in the pass bands and the sharp band edges are obtained and the optimum growth condition is determined. For the best sample, the transmission in the pass bands approaches 0.9 while that in the band gap reaches 0.1. More importantly, the maximum differential transmission as high as 0.1/nm is achieved. In addition, it is found that the number of stacking layers does not increase linearly with concentration of PS spheres in a solution, and a gradual saturation occurs when the concentration of PS spheres exceeds 1.5 wt.%. The uniformity of the fabricated samples is examined by transmission measurements on areas with different sizes. Finally, the tolerance of the fabricated samples to baking was studied.展开更多
One-dimensional photonic crystals (1D PhCs) have a unique ability to control the propagation of light waves, however certain classes of 1D oxides remain relatively unexplored for use as PhCs. Specifically, there has n...One-dimensional photonic crystals (1D PhCs) have a unique ability to control the propagation of light waves, however certain classes of 1D oxides remain relatively unexplored for use as PhCs. Specifically, there has not been a comparative study of the three different 1D PhC structures to compare the influence of layer thickness, number, and refractive index on the ability of the PhCs to control light transmission. Herein, we use the transfer matrix method (TMM) to theoretically examine the transmission of 1D PhCs composed of layers of TiO<sub>2</sub>/SiO<sub>2</sub>, TiO<sub>2</sub>/SnO<sub>2</sub>, SiO<sub>2</sub>/SnO<sub>2</sub>, and combinations of the three with various top and bottom layer thicknesses to cover a substantial region of the electromagnetic spectrum (UV to NIR). With increasing layer numbers for TiO<sub>2</sub>/SiO<sub>2</sub> and SiO<sub>2</sub>/SnO<sub>2</sub>, the edges became sharper and wider and the photonic bandgap width increased. Moreover, we demonstrated that PhCs with significantly thick TiO<sub>2</sub>/SiO<sub>2</sub> layers had a high transmittance for a wide bandgap, allowing for wide-band optical filter applications. These different PhC architectures could enable a variety of applications, depending on the properties needed.展开更多
We demonstrate a method to generate tunable triangular and honeycomb plasma structures via dielectric barrier discharge with uniquely designed mesh-liquid electrodes.A rapid reconfiguration between the triangular latt...We demonstrate a method to generate tunable triangular and honeycomb plasma structures via dielectric barrier discharge with uniquely designed mesh-liquid electrodes.A rapid reconfiguration between the triangular lattice and honeycomb lattice has been realized.Novel structures comprised of triangular plasma elements have been observed and a robust angular reorientation of the triangular plasma elements withθ=π/3 is suggested.An active control on the geometrical shape,size and angular orientation of the plasma elements has been achieved.Moreover,the formation mechanism of different plasma structures is studied by spatial-temporal resolved measurements using a high-speed camera.The photonic band diagrams of the plasma structures are calculated by use of finite element method and two large omnidirectional band gaps have been obtained for honeycomb lattices,demonstrating that such plasma structures can be potentially used as plasma photonic crystals to manipulate the propagation of microwaves.The results may offer new strategies for engineering the band gaps and provide enlightenments on designing new types of 2D and possibly 3D metamaterials in other fields.展开更多
Three-dimensional-structured metal oxides have myriad applications for optoelectronic devices.Comparing to conventional lithography-based manufacturing methods which face significant challenges for 3D device architect...Three-dimensional-structured metal oxides have myriad applications for optoelectronic devices.Comparing to conventional lithography-based manufacturing methods which face significant challenges for 3D device architectures,additive manufacturing approaches such as direct ink writing offer convenient,on-demand manufacturing of 3D oxides with high resolutions down to sub-micrometer scales.However,the lack of a universal ink design strategy greatly limits the choices of printable oxides.Here,a universal,facile synthetic strategy is developed for direct ink writable polymer precursor inks based on metal-polymer coordination effect.Specifically,polyethyleneimine functionalized by ethylenediaminetetraacetic acid is employed as the polymer matrix for adsorbing targeted metal ions.Next,glucose is introduced as a crosslinker for endowing the polymer precursor inks with a thermosetting property required for 3D printing via the Maillard reaction.For demonstrations,binary(i.e.,ZnO,CuO,In_(2)O_(3),Ga_(2)O_(3),TiO_(2),and Y_(2)O_(3)) and ternary metal oxides(i.e.,BaTiO_(3) and SrTiO_(3)) are printed into 3D architectures with sub-micrometer resolution by extruding the inks through ultrafine nozzles.Upon thermal crosslinking and pyrolysis,the 3D microarchitectures with woodpile geometries exhibit strong light-matter coupling in the mid-infrared region.The design strategy for printable inks opens a new pathway toward 3D-printed optoelectronic devices based on functional oxides.展开更多
A low-dimensional ion-pair compound[4-CN-Bz-4-Ph-Py][Ni(mnt)2](1,4-CN-Bz-4-Ph-Py=(4’-cyanobenzyl)-4-phenylpridinium)and mnt^2-=maleonitriledithiolate)was designed and synthesized.The cations and anions of 1 formed ir...A low-dimensional ion-pair compound[4-CN-Bz-4-Ph-Py][Ni(mnt)2](1,4-CN-Bz-4-Ph-Py=(4’-cyanobenzyl)-4-phenylpridinium)and mnt^2-=maleonitriledithiolate)was designed and synthesized.The cations and anions of 1 formed irregular segregated stacks along the a axis.1 exhibits weak paramagnetism over the temperature range of 2~300 K.The dielectric constant of compound 1 is between 2.75 and 5.55 from 30 to 140℃.1 is a very rare metal-bis-dithiolene complex with very low dielectric constant in high temperature.Our results will shed light on the design and preparation of new multi-functional molecular materials combining magnetic and dielectric properties.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
At present,it is very important to create new types of mirrors,nonlinear light frequency transformers and optical filters with controlled optical properties.In this connection,it is of great interest to study photonic...At present,it is very important to create new types of mirrors,nonlinear light frequency transformers and optical filters with controlled optical properties.In this connection,it is of great interest to study photonic crystals.Their dielectric permittivity varies periodically in space with a period permitting Bragg diffraction of light.In this paper,we have investigated the optical properties of mesoporous three-dimensional(3D)opal-type and one-dimensional(1D)anodic alumina photonic crystals,filled with different dielectrics,ferroelectrics and piezoelectrics.We have compared the optical properties of initial mesoporous photonic crystals and filled with different substances.The possibility of mesoporous photonic crystals using selective narrow-band light filters in Raman scattering experiments and nonlinear mirrors has been analyzed.The electromagnetic field enhancing in the case of exciting light frequency close to the stop band edges has been established.The optical harmonics and subharmonics generation in mesoporous crystals,filled with ferroelectrics and piezoelectrics was proposed.展开更多
基金supported by National Natural Science Foundation of China(Nos.12275065 and 11975089)Natural Science Foundation of Hebei Province(Nos.A2021201010 and A2021201003)+4 种基金Interdisciplinary Research Program of Natural Science of Hebei University(No.DXK202108)Hebei Provincial Central Government Guiding Local Science and Technology Development Funds(No.236Z1501G)Scientific Research and Innovation Team Foundation of Hebei University(No.IT2023B03)The Excellent Youth Research Innovation Team of Hebei University(No.QNTD202402)Regional Key Projects of National Natural Science Foundation of China(No.U23A20678).
文摘Archimedean photonic crystal has become a research area of great interest due to its various unique properties. Here, we experimentally demonstrate the realization of reconfigurable(4, 6^(2))and(4, 8^(2)) Archimedean plasma photonic crystals(APPCs) by use of dielectric barrier discharges in air. Dynamical control on both the macrostructures including the lattice symmetry and the crystal orientation, and the microstructures including the fine structures of scattering elements has been achieved. The formation mechanisms of APPCs are studied by time-resolved measurements together with numerical simulations. Large omnidirectional band gaps of APPCs have been obtained. The tunable topology of APPCs may offer new opportunities for fabricating multi-functional and highly-integrated microwave devices.
文摘We present a both theoretical and experimental investigation into the effect of array periodicity on the filtering characteristics of metal/dielectric photonic crystals(MDPhCs) with hexagonal arrays of subwavelength holes in gold/silicon dioxide films,varying the array periodicity from 6 to 8μm every 1μm while the ratio of hole radius to array periodicity is kept constant(1/4).The results indicate that the reflectance spectrum is highly dependent on the array periodicity.When the array periodicity increases,the reflectance spectrum exhibits a large redshift regularly.The finite difference time domain(FDTD) simulations agree well with the experimental results. By analyzing the relationship between the position of the reflectance minimum and the array periodicity,we find that the filtering characteristics of MDPhCs have an almost linear relationship with the array periodicity under the conditions of keeping the same ratio of hole radius to array periodicity(1/4).This finding provides an effective way to control the filtering characteristics of MDPhCs,which have potential applications in optical filters,plasmonic thermal emitters and so on.
基金supported by National Natural Science Foundation of China(No.12075075)the Natural Science Foundation of Hebei Province, China(Nos.2020201016 and A2018201154)。
文摘We report five types of patterns with square symmetry,including three novel types obtained by inserting a specially designed grid photonic crystal(PC)into a dielectric barrier discharge system.They are studied using an intensified charge-coupled device camera and photomultiplier tubes.The three novel types of patterns are a square pattern with one structure,a square superlattice pattern with four sublattices and a(1/4)K_(grid)(K_(grid)is the basic wave vector of the grid),and another square pattern with a complex inversion discharge sequence.From the application viewpoint,the five types of patterns can be used as plasma photonic crystals(PPCs).Their band diagrams under a transverse-magnetic wave simulated by the finite element method show that there are a large number of band gaps.Compared with the original PC with only a unidirectional band gap,the five types of PPCs have tunable and omnidirectional band gaps,which is very important in controlling the propagation of electromagnetic waves in the mm-wave region.The experimental results enrich the pattern types in the dielectric barrier discharge system and provide a method for obtaining PPCs with symmetry controllability and bandgap tunability.
文摘The optical transmission properties of two types of photonic crystals have been analyzed by using the transfer matrix method. The first one is the dielectric photonic crystal (DPC), and the second is the metallic photonic crystal (MPC). We found the dielectric and metallic photonic crystals have different transmission spectra. The effect of the most prameters on the transmission spectra of the dielectric and metallic photonic crystals has been studied.
基金Project supported by the National 973 (Grant No 2004CB719804) and the National Natural Science Foundation of China.
文摘This paper has theoretically studied the characteristic frequencies of band structures in two-dimensional metallic- dielectric photonic crystals. It is demonstrated that a large filling fraction benefits the existence of absolute photonic band gap, while a smaller filling fraction benefits an absolute negative refraction band. In addition, it also finds that the relation between the cut-off frequency of E-polarized wave and the filling fraction exceeding 10% is content with a linear increasing function, whose coefficients are exponential to the normalized lattice constant. These investigations have significant implications for tuning the operational frequencies to desired applications and manufacturing photonic crystals.
基金Project supported by the Natural Science Foundation of Hebei Province, China (Grants No. A2011201010)the Research Foundation of Education Bureauof Hebei Province, China (Grant No. 2010113)
文摘A novel one-dimensional plasma photonic crystal whose crystal orientation can change spontaneously is demonstrated using a dielectric barrier discharge with two liquid electrodes. The orientation of the plasma photonic crystal will vary from transverse to longitudinal or vary from longitudinal to transverse and then revert to longitudinal by self-adjustment, while the experimental conditions are kept fixed. The dispersion relation of these plasma photonic crystals are calculated, and the changes of the photonic band diagrams during the orientation transition are studied.
基金supported by the State Key Basic Research Program of China under Grant No.2006CB921607China-Australia Special Fund for Science and Technology
文摘A two-dimensional photonic crystal with a one-dimensional periodic dielectric background is proposed. The photonic band modulation effects due to the periodic background are investigated based on the plane wave expansion method. We find that periodic modulation of the dielectric background greatly alters photonic band structures, especially for the E-polarization modes. The number, width and position of the photonic band gaps (PBGs) sensitively depend on the structure parameters (the layer thicknesses and dielectric constants) of the one-dimensional periodic background,
基金supported by the Natural Science Foundation of China (Nos. 50061001 and 50661001)the Science Foundation of Guangxi Province,China(Nos. 0991026,0832029 and 0639004)
文摘The characteristics of photonic forbidden bands, transmission gain and absorption of one-dimensional (ID) dual-periodical photonic crystals (PC) with a complex dielectric layer were studied by using the optical transfer matrix (TM) method. The results show that the photonic band gap (PBG) of this structure is enlarged and many transmission resonance peaks appear in PBG. Large transmission gain for transmission peaks is obtained if the imaginary part of dielectric constant is negative. With the increase of the absolute value of the imaginary part, the transmission gain increases firstly and the transmittance gain gets to an apex. The imaginary parts of dielectric constant corresponding to transmission gain apex are different according to wavelength. However, the transmission ratio of resonance peaks is less than 1 if the imagi- nary part of dielectric constant is positive. The properties might be used to design multi-narrow-channel band filters and optical amplification devices synchronously.
基金funded by the Postdoctoral Foundation of Jiangsu Province (No. 1501016A)China Postdoctoral Science Foundation (No. 2015M581790)the Special Grade China Postdoctoral Science Foundation (No. 2016T90455)
文摘The features of the band structures of woodpile three-dimensional (3D) photonic crystals composed of plasma and function dielectric constituents, referred to as function plasma photonic crystals (FPPCs), are theoretically studied by a modified plane wave expansion method, and the formulas for computing the band structures are derived. The arrangement for the proposed FPPCs is that the function dielectric columns are surrounded by plasma, and the embedded dielectric columns are stacked according to the woodpile lattices, which are arrayed with facecentered-tetragonal symmetry. The relative permittivity of function dielectric rods depends on the function coefficient and space coordinates. The relationships between the parameters for inserted function dielectric rods and plasma and the band structures are also investigated. The computed results illustrate that the obtained PBG can be tuned by those parameters as mentioned above. Compared to dielectric-air PCs, function dielectric PCs and plasma dielectric PCs with the same topology, a wider bandwidth of the photonic band gap can be observed in the proposed FPPCs. The calculated results also show us another alternative way to realize reconfigurable applications with 3D FPPCs.
基金Supported by the National Natural Science Foundation of China (50425206, 50702038)
文摘Using the rigorous multiple-scattering theory, we study the dispersion relation of electromagnetic (EM) waves in two dimensional dielectric photonic crystals (PCs) and metallic photonic crystals (MPCs) in the low-frequency limit. Analytic formula for the effective velocity of EM waves in PCs and MPCs is obtained. Accuracy of our formula is checked by comparing the results with rigorous calculations. For PCs, our result is exactly the same as the coherent potential approximation (CPA), which is accurate even when the filling fraction is high. But for MPCs, our approach demonstrates special advantages, while the CPA theory fails, in predicting the effective velocity of EM waves in MPCs at low frequency.
文摘The transfer matrix method is used to study the effect of the permittivity profile on the reflectivity of a one dimensional plasma photonic crystal having exponentially graded material. The analysis shows that the proposed structure works as a perfect mirror within a certain frequency range. These frequency ranges can be completely controlled by the permittivity profile of a graded dielectric layer. As expected we observed that these frequency ranges are also controlled by plasma parameters.
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Project supported by the National Natural Science Foundation of China (Grant No 10674051)the Natural Science Foundation of Guangdong province, China (Grant No 06025082)+1 种基金the Program for Innovative Research Team of the Higher Education in Guangdong (Grant No 06CXTD005)the Program for New Century Excellent Talents (NCET) in University of China (Grant No ncet-04-0829)
文摘Application of the pressure controlled isothermal heating vertical deposition method to the fabrication of colloidal photonic crystals is systematically investigated in this paper. The fabricated samples are characterized by scanning electron microscope and transmission spectrum. High-quality samples with large transmissions in the pass bands and the sharp band edges are obtained and the optimum growth condition is determined. For the best sample, the transmission in the pass bands approaches 0.9 while that in the band gap reaches 0.1. More importantly, the maximum differential transmission as high as 0.1/nm is achieved. In addition, it is found that the number of stacking layers does not increase linearly with concentration of PS spheres in a solution, and a gradual saturation occurs when the concentration of PS spheres exceeds 1.5 wt.%. The uniformity of the fabricated samples is examined by transmission measurements on areas with different sizes. Finally, the tolerance of the fabricated samples to baking was studied.
文摘One-dimensional photonic crystals (1D PhCs) have a unique ability to control the propagation of light waves, however certain classes of 1D oxides remain relatively unexplored for use as PhCs. Specifically, there has not been a comparative study of the three different 1D PhC structures to compare the influence of layer thickness, number, and refractive index on the ability of the PhCs to control light transmission. Herein, we use the transfer matrix method (TMM) to theoretically examine the transmission of 1D PhCs composed of layers of TiO<sub>2</sub>/SiO<sub>2</sub>, TiO<sub>2</sub>/SnO<sub>2</sub>, SiO<sub>2</sub>/SnO<sub>2</sub>, and combinations of the three with various top and bottom layer thicknesses to cover a substantial region of the electromagnetic spectrum (UV to NIR). With increasing layer numbers for TiO<sub>2</sub>/SiO<sub>2</sub> and SiO<sub>2</sub>/SnO<sub>2</sub>, the edges became sharper and wider and the photonic bandgap width increased. Moreover, we demonstrated that PhCs with significantly thick TiO<sub>2</sub>/SiO<sub>2</sub> layers had a high transmittance for a wide bandgap, allowing for wide-band optical filter applications. These different PhC architectures could enable a variety of applications, depending on the properties needed.
基金supported by National Natural Science Foundation of China(Nos.11875014,11975089)the Natural Science Foundation of Hebei Province(Nos.A2021201010,A2021201003,and A2017201099)。
文摘We demonstrate a method to generate tunable triangular and honeycomb plasma structures via dielectric barrier discharge with uniquely designed mesh-liquid electrodes.A rapid reconfiguration between the triangular lattice and honeycomb lattice has been realized.Novel structures comprised of triangular plasma elements have been observed and a robust angular reorientation of the triangular plasma elements withθ=π/3 is suggested.An active control on the geometrical shape,size and angular orientation of the plasma elements has been achieved.Moreover,the formation mechanism of different plasma structures is studied by spatial-temporal resolved measurements using a high-speed camera.The photonic band diagrams of the plasma structures are calculated by use of finite element method and two large omnidirectional band gaps have been obtained for honeycomb lattices,demonstrating that such plasma structures can be potentially used as plasma photonic crystals to manipulate the propagation of microwaves.The results may offer new strategies for engineering the band gaps and provide enlightenments on designing new types of 2D and possibly 3D metamaterials in other fields.
基金financial support of this research by the National Natural Science Foundation of China (No. 51905446)the Research Center for Industries of the Future (RCIF) at Westlake University for partially supporting this work。
文摘Three-dimensional-structured metal oxides have myriad applications for optoelectronic devices.Comparing to conventional lithography-based manufacturing methods which face significant challenges for 3D device architectures,additive manufacturing approaches such as direct ink writing offer convenient,on-demand manufacturing of 3D oxides with high resolutions down to sub-micrometer scales.However,the lack of a universal ink design strategy greatly limits the choices of printable oxides.Here,a universal,facile synthetic strategy is developed for direct ink writable polymer precursor inks based on metal-polymer coordination effect.Specifically,polyethyleneimine functionalized by ethylenediaminetetraacetic acid is employed as the polymer matrix for adsorbing targeted metal ions.Next,glucose is introduced as a crosslinker for endowing the polymer precursor inks with a thermosetting property required for 3D printing via the Maillard reaction.For demonstrations,binary(i.e.,ZnO,CuO,In_(2)O_(3),Ga_(2)O_(3),TiO_(2),and Y_(2)O_(3)) and ternary metal oxides(i.e.,BaTiO_(3) and SrTiO_(3)) are printed into 3D architectures with sub-micrometer resolution by extruding the inks through ultrafine nozzles.Upon thermal crosslinking and pyrolysis,the 3D microarchitectures with woodpile geometries exhibit strong light-matter coupling in the mid-infrared region.The design strategy for printable inks opens a new pathway toward 3D-printed optoelectronic devices based on functional oxides.
基金supported by the Natural Science Foundation of Jiangsu Province and Natural Science Training Foundation of Nanjing Xiaozhuang University(Nos.BK20171125 and 2016NXY12)
文摘A low-dimensional ion-pair compound[4-CN-Bz-4-Ph-Py][Ni(mnt)2](1,4-CN-Bz-4-Ph-Py=(4’-cyanobenzyl)-4-phenylpridinium)and mnt^2-=maleonitriledithiolate)was designed and synthesized.The cations and anions of 1 formed irregular segregated stacks along the a axis.1 exhibits weak paramagnetism over the temperature range of 2~300 K.The dielectric constant of compound 1 is between 2.75 and 5.55 from 30 to 140℃.1 is a very rare metal-bis-dithiolene complex with very low dielectric constant in high temperature.Our results will shed light on the design and preparation of new multi-functional molecular materials combining magnetic and dielectric properties.
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supported by Russian Foundation for Basic Research(RFBR)(grants 15-02-02882,16-08-00618,16-02-00488,16-52-00026)National Natural Science Foundation of China(Nos.51471162,51671183,51502294)China Scholarship Council.
文摘At present,it is very important to create new types of mirrors,nonlinear light frequency transformers and optical filters with controlled optical properties.In this connection,it is of great interest to study photonic crystals.Their dielectric permittivity varies periodically in space with a period permitting Bragg diffraction of light.In this paper,we have investigated the optical properties of mesoporous three-dimensional(3D)opal-type and one-dimensional(1D)anodic alumina photonic crystals,filled with different dielectrics,ferroelectrics and piezoelectrics.We have compared the optical properties of initial mesoporous photonic crystals and filled with different substances.The possibility of mesoporous photonic crystals using selective narrow-band light filters in Raman scattering experiments and nonlinear mirrors has been analyzed.The electromagnetic field enhancing in the case of exciting light frequency close to the stop band edges has been established.The optical harmonics and subharmonics generation in mesoporous crystals,filled with ferroelectrics and piezoelectrics was proposed.