Color filters are essential components for optical modulation.However,conventional filters are restricted to operating exclusively in either reflective or transmissive mode.Furthermore,they suffer from limited UV and ...Color filters are essential components for optical modulation.However,conventional filters are restricted to operating exclusively in either reflective or transmissive mode.Furthermore,they suffer from limited UV and thermal stability,low color purity,and exhibit identical coloration on both surfaces.Herein,we propose a novel design strategy for trans-reflective color filters by integrating the absorptive properties of dye-doped polysulfone(PSU)with the diffractive capabilities of photonic crystals.This composite filter achieved broad-spectrum transmission with deep color outputs—yellow(0.410,0.510),magenta(0.446,0.231),and cyan(0.201,0.425)—closely aligned with standard color space coordinates.By tuning the refractive index of CeO_(2)@SiO_(2)nanoparticles to match dye-based PSU matrix,the transmittance of filters exceeded 70%.Moreover,dye-mediated absorption reduces the scattering light,thereby enhancing reflection color purity(full width at half maxima(FWHM)=25 nm)and producing vibrant blue,green,and red hues.The incorporation of UV-absorbing CeO_(2)@SiO_(2)nanoparticles effectively mitigated dye photodegradation,yielding exceptional UV stability(ΔT<2%under prolonged UV exposure).The filters also exhibited outstanding thermal stability(ΔT<1%after 30 min heat treatment at 230°C).This work establishes a robust materials design framework for multifunctional optical filters,advancing the development of highfidelity dual-mode color systems for next-generation display technologies.展开更多
This paper examines the connection between photonic band-gap formation in two types of two-dimensional photonic crystals and the emergence of reverse electromagnetic energy flows generated by linearly polarized plane ...This paper examines the connection between photonic band-gap formation in two types of two-dimensional photonic crystals and the emergence of reverse electromagnetic energy flows generated by linearly polarized plane waves incident on a photonic-crystal slab.We show that these reverse energy flows,observed in both transmitted and reflected fields,originate from vortex structures in the Poynting vector.The resulting energy-flow patterns exhibit striking analogies to vortex formation in fluid motion past obstacles.The geometry and dynamics of the Poynting-vector vortices determine whether the incident electromagnetic energy is impeded,leading to the formation of photonic band gaps,or instead guided through the structure,enabling transmission.展开更多
Realizing the valley Hall effect by breaking the spatial inversion symmetry of photonic systems has become a cutting-edge field of micro-nano-optics,since the valley degree of freedom was introduced into photonic syst...Realizing the valley Hall effect by breaking the spatial inversion symmetry of photonic systems has become a cutting-edge field of micro-nano-optics,since the valley degree of freedom was introduced into photonic system.Various novel devices based on the domain walls of the valley photonic crystals have also been demonstrated.In this article,we investigate the variation of edge states by the modulation of refractive index within the domain walls,and the geometric difference between the dielectric columns of the sublattices.Straight photonic crystal waveguides with three types of domain walls(bearded,zigzag,armchair)are constructed.Simulation results show that the creation of a double-edge state in the band diagram results in two windows of stable transmission in tunable bands.Our findings might have significant implications in the field of novel optical devices.展开更多
Tamm plasmon polaritons(TPPs)are localized photonic states at the interface between a metal layer and one-dimensional(1D)photonic crystal substrate.Unlike surface plasmon polaritons(SPPs),TPPs can be excited by both t...Tamm plasmon polaritons(TPPs)are localized photonic states at the interface between a metal layer and one-dimensional(1D)photonic crystal substrate.Unlike surface plasmon polaritons(SPPs),TPPs can be excited by both transverse magnetic and electric waves without requiring additional coupling optics.TPPs offer robust color filtering,making them ideal for applications such as complementary metal oxide semiconductor(CMOS)image detectors.However,obtaining a large-area,reversible,and reconfigurable filter remains challenging.This study demonstrates a dynamically reconfigurable reflective color filter by integrating an ultrathin antimony trisulfide(Sb_(2)S_(3))layer with Tamm plasmonic photonic crystals.Reconfigurable tuning was achieved by inducing Sb_(2)S_(3) crystallization and reamorphization via thermal and optical activation,respectively.The material exhibited good stability after multiple switching cycles.The reflectance spectrum can be tuned across the visible range,with a shift of approximately 50 nm by switching Sb_(2)S_(3) between its amorphous and crystalline phases.This phase transition is nonvolatile and substantially minimizes the energy consumption,enhancing efficiency for practical applications.Tamm plasmonic photonic crystals are low-cost and large-scale production,offering a platform for compact color display systems and customizable photonic crystal filters for realistic system integration.展开更多
We study the topological states(TSs)of all-dielectric honeycomb valley photonic crystals(VPCs).Breaking the space inversion symmetry of the honeycomb lattice by varying the filling ratio of materials for circular ring...We study the topological states(TSs)of all-dielectric honeycomb valley photonic crystals(VPCs).Breaking the space inversion symmetry of the honeycomb lattice by varying the filling ratio of materials for circular ring dielectric columns in the unit cell,which triggers topological phase transitions and thus achieves topological edge states(TESs)and topological corner states(TCSs).The results demonstrate that this structure has efficient photon transmission characteristics and anti-scattering robustness.In particular,we have found that changing the type of edge splicing between VPCs with different topological properties produces a change in the frequency of TCSs,and then based on this phenomenon,we have used a new method of adjusting only the type of edge splicing of the structure to design a novel TCSs combiner that can integrate four TCSs with different frequencies.This work not only expands the variety and number of unexplored TCSs that may exist in a fixed photonic band gap and can be rationalized to be selectively excited in the fixed configuration.Our study provides a feasible pathway for the design of integrated optical devices in which multiple TSs coexist in a single photonic system.展开更多
Traditional stealth materials do not fulfill the requirements of high absorption for radar waves and low emissivity for infrared waves.Furthermore,they can be detected by various technologies,considerably threatening ...Traditional stealth materials do not fulfill the requirements of high absorption for radar waves and low emissivity for infrared waves.Furthermore,they can be detected by various technologies,considerably threatening weapon safety.Therefore,a stealth material compatible with radar and infrared was designed based on the photonic bandgap characteristics of photonic crystals.The radar stealth lay-er(bottom layer)is a composite of carbonyl iron/silicon dioxide/epoxy resin,and the infrared stealth layer(top layer)is a 1D photonic crystal with alternately and periodically stacked germanium and silicon nitride.Through composition optimization and structural adjust-ment,the effective absorption bandwidth of the compatible stealth material with a reflection loss of less than-10 dB has reached 4.95 GHz.The average infrared emissivity of the proposed design is 0.1063,indicating good stealth performance.The theoretical analysis proves that photonic crystals with this structural design can produce infrared waves within the photonic bandgap,achieving high radar wave transmittance and low infrared emissivity.Infrared stealth is achieved without affecting the absorption performance of the radar stealth layer,and the conflict between radar and infrared stealth performance is resolved.This work aims to promote the application of photonic crystals in compatible stealth materials and the development of stealth technology and to provide a design and theoretical found-ation for related experiments and research.展开更多
The generation of optical vortices from nonlinear photonic crystals(NPCs)with spatially modulated second-order nonlinearity offers a promising approach to extend the working wavelength and topological charge of vortex...The generation of optical vortices from nonlinear photonic crystals(NPCs)with spatially modulated second-order nonlinearity offers a promising approach to extend the working wavelength and topological charge of vortex beams for various applications.In this work,the second harmonic(SH)optical vortex beams generated from nonlinear fork gratings under Gaussian beam illumination are numerically investigated.The far-field intensity and phase distributions,as well as the orbital angular momentum(OAM)spectra of the SH beams,are analyzed for different structural topological charges and diffraction orders.Results reveal that higher-order diffraction and larger structural topological charges lead to angular interference patterns and non-uniform intensity distributions,deviating from the standard vortex profile.To optimize the SH vortex quality,the effects of the fundamental wave beam waist,crystal thickness,and grating duty cycle are explored.It is shown that increasing the beam waist can effectively suppress diffraction order interference and improve the beam’s quality.This study provides theoretical guidance for enhancing the performance of nonlinear optical devices based on NPCs.展开更多
To save finite-difference time-domain（FDTD） computing time, several methods are proposed to convert the time domain FDTD output into frequency domain. The Pad6 approximation with Baker＇s algorithm and the program a...To save finite-difference time-domain（FDTD） computing time, several methods are proposed to convert the time domain FDTD output into frequency domain. The Pad6 approximation with Baker＇s algorithm and the program are introduced to simulate photonic crystal structures. For a simple pole system with frequency 160THz and quality factor of 5000, the intensity spectrum obtained by the Padé approximation from a 2^8-item sequence output is more exact than that obtained by fast Fourier transformation from a 2^20-item sequence output. The mode frequencies and quality factors are calculated at different wave vectors for the photonic crystal slab from a much shorter FDTD output than that required by the FFT method, and then the band diagrams are obatined. In addition, mode frequencies and Q-factors are calculated for photonic crystal microcavity.展开更多
The band structure of 2D photonic crystals (PCs) and localized states resulting from defects are analyzed by finite-difference time-domain (FDTD) technique and Padé approximation.The effect of dielectric constant...The band structure of 2D photonic crystals (PCs) and localized states resulting from defects are analyzed by finite-difference time-domain (FDTD) technique and Padé approximation.The effect of dielectric constant contrast and filling factor on photonic bandgap (PBG) for perfect PCs and localized states in PCs with point defects are investigated.The resonant frequencies and quality factors are calculated for PCs with different defects.The numerical results show that it is possible to modulate the location,width and number of PBGs and frequencies of the localized states only by changing the dielectric constant contrast and filling factor.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 a...展开更多
We theoretically investigate the photonic band gap in one-dimensional photonic crystals with a graded multilayer structure. The proposed structure constitutes an alternating composite layer （metallic nanoparticles em...We theoretically investigate the photonic band gap in one-dimensional photonic crystals with a graded multilayer structure. The proposed structure constitutes an alternating composite layer （metallic nanoparticles embedded in TiO2 film） and an air layer. Regarding the multilayer as a series of capacitance, effective optical properties are derived. The dispersion relation is obtained with the solution of the transfer matrix equation. With a graded structure in the composite layer, numerical results show that the position and width of the photonic band gap can be effectively modulated by varying the number of the graded composite layers, the volume fraction of nanoparticles and the external stimuli.展开更多
Ordered macroporous titania photonic crystals （PCs） and photonic balls were fabricated by functional modified polymer colloidal crystals. The TiO2 PCs and balls formed through this method exhibit no cracks and lacun...Ordered macroporous titania photonic crystals （PCs） and photonic balls were fabricated by functional modified polymer colloidal crystals. The TiO2 PCs and balls formed through this method exhibit no cracks and lacunae in large areas on their surface and their inner structures.展开更多
Transmission spectra of triangular lattice photonic crystals milled in the top surface of an annealed proton- exchange waveguide are numerically simulated. The effects of the finite depth, conical shape, trapezoidal s...Transmission spectra of triangular lattice photonic crystals milled in the top surface of an annealed proton- exchange waveguide are numerically simulated. The effects of the finite depth, conical shape, trapezoidal shape and hybrid shape of holes are theoretically analyzed. Due to the difficulty of milling high aspect-ratio cylindrical holes in lithium niobate （LiNbO3 ）, a compromised solution is proposed to improve the overlap between shallow holes and the waveguide mode, and useful transmission spectra with strong contrast and sharp band edges are achieved.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 thermal-responsive photonic crystal material was fabricated by forming an inverse opal nanocomposite hydrogel of poly(N-isopropylacrylamide)(IONHPNIPAm)within the interstitial space of a polystyrene photonic crystal...A thermal-responsive photonic crystal material was fabricated by forming an inverse opal nanocomposite hydrogel of poly(N-isopropylacrylamide)(IONHPNIPAm)within the interstitial space of a polystyrene photonic crystal template.In IONHPNIPAm,PNIPAm were physically cross-linked with two kinds of nanoparticles(carbon dots and laponite clays).The integration of carbon dots and laponite clays for physical crosslinking endowed IONHPNIPAm sufficient strength and self-healing property.IONHPNIPAm films can be completely peeled from the substrates to be utilized as an independent photonic crystal material.The structural color and optical diffraction of the IONHPNIPAm exhibits a rapid reversible change in response to external thermal stimuli due to its physical cross-linking feature.Moreover,the IONHPNIPAm shows clear fluorescence due to the introduction of carbon dots,which enables a convenient way for chemical detection(such as the detection of silver ions).This stimuli-responsive photonic crystal materials based on physically cross-linked inverse opal nanocomposite hydrogels with fast response and good mechanical stability are promising for applications in the fields of smart optical detectors,thermal-responsive sensors and chemical detectors.展开更多
Group velocity （GV） of eigenmode is a crucial parameter to explain the extraordinary phenomena about light propagation in photonic crystals （PhCs）. To study relationships between group velocity and symmetry of PhC...Group velocity （GV） of eigenmode is a crucial parameter to explain the extraordinary phenomena about light propagation in photonic crystals （PhCs）. To study relationships between group velocity and symmetry of PhCs, a new general expression of CV in PhCs made up of non-dispersive material is introduced. Based on this, the CVs of eigenmodes of PhCs, especially those of degenerate eigenmodes at highly symmetric points in the first Brillouin zone, are discussed. Some interesting results are obtained. For example, the summation of degenerate eigenmodes＇ CVs is invariant under the operations of wave vector K-group MK. In addition, some numerical results are presented to verify them.展开更多
An electrically driven, single-longitudinal-mode GaAs based photonic crystal （PC） ridge waveguide （RWG） laser emitting at around 850 nm is demonstrated. The single-longitudinal-mode lasing characteristic is achiev...An electrically driven, single-longitudinal-mode GaAs based photonic crystal （PC） ridge waveguide （RWG） laser emitting at around 850 nm is demonstrated. The single-longitudinal-mode lasing characteristic is achieved by introducing the PC to the RWG laser. The triangle PC is etched on both sides of the ridge by photolithography and inductive coupled plasma （ICP） etching. The lasing spectra of the RWG lasers with and without the PC are studied, and the result shows that the PC purifies the longitudinal mode. The power per facet versus current and current-voltage characteristics have also been studied and compared.展开更多
To obtain the adjustable photonic crystals (PCs), we numerically investigate one-dimensional (1D) PCs with alternating VO2 and SiO2 layers through transfer matrix method. The dispersion relation agrees well with the t...To obtain the adjustable photonic crystals (PCs), we numerically investigate one-dimensional (1D) PCs with alternating VO2 and SiO2 layers through transfer matrix method. The dispersion relation agrees well with the transmittance obtained by the finite element calculation. Tunable band gaps are achieved with the thermal stimuli of VO2, which has two crystal structures. The monoclinic crystal structure VO2 (R) at low temperature exhibits insulating property, and the high temperature square rutile structure VO2 (M) presents metal state. Concretely, the bandwidth is getting narrower and red shift occurs with the higher temperature in VO2 (R)/SiO2 PCs structure. Based on the phase change characteristics of VO2, we can flexibly adjust the original structure as VO2 (R)/VO2 (M)/SiO2. By increasing the phase ratio of VO2 (R) to VO2 (M), the band gap width gradually becomes wider and blue shift occurs. The discrete layers of gradient composites on the dispersion of 1D PCs are also investigated, which enhances the feasibility in practical operation. Thus, our proposed thermal modulation PCs structure paves a new way to realize thermal tunable optical filters and sensors.展开更多
Plasma photonic crystals(PPCs)are emerging as a powerful instrument for the dynamical control of the electromagnetic properties of a propagating wave.Here we demonstrate several one-dimensional(1 D)PPCs with uniquely ...Plasma photonic crystals(PPCs)are emerging as a powerful instrument for the dynamical control of the electromagnetic properties of a propagating wave.Here we demonstrate several one-dimensional(1 D)PPCs with uniquely designed superlattice structures,annular structures or with incorporation of the third material into the primitive unit cell.The influences of the properties of the third material as well as the structural configurations of suplerlattices on the transmittance characteristics of PPCs have been investigated by use of the finite element method.The optimal design strategy for producing PPCs that have more and larger band gaps is provided.These new schemes can potentially be extended to 2 D or 3 D plasma crystals,which may find broad applications in the manipulation of microwaves and terahertz waves.展开更多
We present a new type of optical filter with an ultra-narrow bandwidth and a wide field-of-view （FOV）. This kind of optical filter consists of one-dimensional photonic crystal （PC） incorporating an anomalous-dispe...We present a new type of optical filter with an ultra-narrow bandwidth and a wide field-of-view （FOV）. This kind of optical filter consists of one-dimensional photonic crystal （PC） incorporating an anomalous-dispersion-material （ADM） with, for instance, an anomalous dispersion of 6P3/2←6S1/2 hyperfine structure transition of a caesium atom. The transmission spectra of optical filters are calculated by using the transfer-matrix method. The simulation results show that the designed optical filter has a bandwidth narrower than 0.33GHz and a wide FOV of ±30°as well. The response of transmission spectrum to an external magnetic field is also investigated.展开更多
基金supported by the Program of the National Natural Science Foundation of China(22238002)the Fundamental Research Funds for the Central Universities(DUT22-LAB610)Research and Innovation Team Project of Dalian University of Technology(DUT2022TB10).
文摘Color filters are essential components for optical modulation.However,conventional filters are restricted to operating exclusively in either reflective or transmissive mode.Furthermore,they suffer from limited UV and thermal stability,low color purity,and exhibit identical coloration on both surfaces.Herein,we propose a novel design strategy for trans-reflective color filters by integrating the absorptive properties of dye-doped polysulfone(PSU)with the diffractive capabilities of photonic crystals.This composite filter achieved broad-spectrum transmission with deep color outputs—yellow(0.410,0.510),magenta(0.446,0.231),and cyan(0.201,0.425)—closely aligned with standard color space coordinates.By tuning the refractive index of CeO_(2)@SiO_(2)nanoparticles to match dye-based PSU matrix,the transmittance of filters exceeded 70%.Moreover,dye-mediated absorption reduces the scattering light,thereby enhancing reflection color purity(full width at half maxima(FWHM)=25 nm)and producing vibrant blue,green,and red hues.The incorporation of UV-absorbing CeO_(2)@SiO_(2)nanoparticles effectively mitigated dye photodegradation,yielding exceptional UV stability(ΔT<2%under prolonged UV exposure).The filters also exhibited outstanding thermal stability(ΔT<1%after 30 min heat treatment at 230°C).This work establishes a robust materials design framework for multifunctional optical filters,advancing the development of highfidelity dual-mode color systems for next-generation display technologies.
文摘This paper examines the connection between photonic band-gap formation in two types of two-dimensional photonic crystals and the emergence of reverse electromagnetic energy flows generated by linearly polarized plane waves incident on a photonic-crystal slab.We show that these reverse energy flows,observed in both transmitted and reflected fields,originate from vortex structures in the Poynting vector.The resulting energy-flow patterns exhibit striking analogies to vortex formation in fluid motion past obstacles.The geometry and dynamics of the Poynting-vector vortices determine whether the incident electromagnetic energy is impeded,leading to the formation of photonic band gaps,or instead guided through the structure,enabling transmission.
基金supported by the Self-Deployment Project Research Program of the Haixi Institutes,Chinese Academy of Sciences(No.CXZX-2022-GH09)the National Natural Science Foundation of China(No.11774103)the Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(No.2021ZR114)。
文摘Realizing the valley Hall effect by breaking the spatial inversion symmetry of photonic systems has become a cutting-edge field of micro-nano-optics,since the valley degree of freedom was introduced into photonic system.Various novel devices based on the domain walls of the valley photonic crystals have also been demonstrated.In this article,we investigate the variation of edge states by the modulation of refractive index within the domain walls,and the geometric difference between the dielectric columns of the sublattices.Straight photonic crystal waveguides with three types of domain walls(bearded,zigzag,armchair)are constructed.Simulation results show that the creation of a double-edge state in the band diagram results in two windows of stable transmission in tunable bands.Our findings might have significant implications in the field of novel optical devices.
文摘Tamm plasmon polaritons(TPPs)are localized photonic states at the interface between a metal layer and one-dimensional(1D)photonic crystal substrate.Unlike surface plasmon polaritons(SPPs),TPPs can be excited by both transverse magnetic and electric waves without requiring additional coupling optics.TPPs offer robust color filtering,making them ideal for applications such as complementary metal oxide semiconductor(CMOS)image detectors.However,obtaining a large-area,reversible,and reconfigurable filter remains challenging.This study demonstrates a dynamically reconfigurable reflective color filter by integrating an ultrathin antimony trisulfide(Sb_(2)S_(3))layer with Tamm plasmonic photonic crystals.Reconfigurable tuning was achieved by inducing Sb_(2)S_(3) crystallization and reamorphization via thermal and optical activation,respectively.The material exhibited good stability after multiple switching cycles.The reflectance spectrum can be tuned across the visible range,with a shift of approximately 50 nm by switching Sb_(2)S_(3) between its amorphous and crystalline phases.This phase transition is nonvolatile and substantially minimizes the energy consumption,enhancing efficiency for practical applications.Tamm plasmonic photonic crystals are low-cost and large-scale production,offering a platform for compact color display systems and customizable photonic crystal filters for realistic system integration.
文摘We study the topological states(TSs)of all-dielectric honeycomb valley photonic crystals(VPCs).Breaking the space inversion symmetry of the honeycomb lattice by varying the filling ratio of materials for circular ring dielectric columns in the unit cell,which triggers topological phase transitions and thus achieves topological edge states(TESs)and topological corner states(TCSs).The results demonstrate that this structure has efficient photon transmission characteristics and anti-scattering robustness.In particular,we have found that changing the type of edge splicing between VPCs with different topological properties produces a change in the frequency of TCSs,and then based on this phenomenon,we have used a new method of adjusting only the type of edge splicing of the structure to design a novel TCSs combiner that can integrate four TCSs with different frequencies.This work not only expands the variety and number of unexplored TCSs that may exist in a fixed photonic band gap and can be rationalized to be selectively excited in the fixed configuration.Our study provides a feasible pathway for the design of integrated optical devices in which multiple TSs coexist in a single photonic system.
基金supported by the National Natural Science Foundation of China(Nos.52071053,U1704253,and 52103334).
文摘Traditional stealth materials do not fulfill the requirements of high absorption for radar waves and low emissivity for infrared waves.Furthermore,they can be detected by various technologies,considerably threatening weapon safety.Therefore,a stealth material compatible with radar and infrared was designed based on the photonic bandgap characteristics of photonic crystals.The radar stealth lay-er(bottom layer)is a composite of carbonyl iron/silicon dioxide/epoxy resin,and the infrared stealth layer(top layer)is a 1D photonic crystal with alternately and periodically stacked germanium and silicon nitride.Through composition optimization and structural adjust-ment,the effective absorption bandwidth of the compatible stealth material with a reflection loss of less than-10 dB has reached 4.95 GHz.The average infrared emissivity of the proposed design is 0.1063,indicating good stealth performance.The theoretical analysis proves that photonic crystals with this structural design can produce infrared waves within the photonic bandgap,achieving high radar wave transmittance and low infrared emissivity.Infrared stealth is achieved without affecting the absorption performance of the radar stealth layer,and the conflict between radar and infrared stealth performance is resolved.This work aims to promote the application of photonic crystals in compatible stealth materials and the development of stealth technology and to provide a design and theoretical found-ation for related experiments and research.
基金supported by the National Nat-ural Science Foundation of China(Nos.12192251,12174185,92163216,and 62288101).
文摘The generation of optical vortices from nonlinear photonic crystals(NPCs)with spatially modulated second-order nonlinearity offers a promising approach to extend the working wavelength and topological charge of vortex beams for various applications.In this work,the second harmonic(SH)optical vortex beams generated from nonlinear fork gratings under Gaussian beam illumination are numerically investigated.The far-field intensity and phase distributions,as well as the orbital angular momentum(OAM)spectra of the SH beams,are analyzed for different structural topological charges and diffraction orders.Results reveal that higher-order diffraction and larger structural topological charges lead to angular interference patterns and non-uniform intensity distributions,deviating from the standard vortex profile.To optimize the SH vortex quality,the effects of the fundamental wave beam waist,crystal thickness,and grating duty cycle are explored.It is shown that increasing the beam waist can effectively suppress diffraction order interference and improve the beam’s quality.This study provides theoretical guidance for enhancing the performance of nonlinear optical devices based on NPCs.
文摘To save finite-difference time-domain（FDTD） computing time, several methods are proposed to convert the time domain FDTD output into frequency domain. The Pad6 approximation with Baker＇s algorithm and the program are introduced to simulate photonic crystal structures. For a simple pole system with frequency 160THz and quality factor of 5000, the intensity spectrum obtained by the Padé approximation from a 2^8-item sequence output is more exact than that obtained by fast Fourier transformation from a 2^20-item sequence output. The mode frequencies and quality factors are calculated at different wave vectors for the photonic crystal slab from a much shorter FDTD output than that required by the FFT method, and then the band diagrams are obatined. In addition, mode frequencies and Q-factors are calculated for photonic crystal microcavity.
文摘The band structure of 2D photonic crystals (PCs) and localized states resulting from defects are analyzed by finite-difference time-domain (FDTD) technique and Padé approximation.The effect of dielectric constant contrast and filling factor on photonic bandgap (PBG) for perfect PCs and localized states in PCs with point defects are investigated.The resonant frequencies and quality factors are calculated for PCs with different defects.The numerical results show that it is possible to modulate the location,width and number of PBGs and frequencies of the localized states only by changing the dielectric constant contrast and filling factor.
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 a...
基金the National Natural Science Foundation of China(Grant Nos.10974183 and 11104252)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20114101110003)+4 种基金the Fund for Science and Technology Innovation Team of Zhengzhou(2011-03)the Aeronautical Science Foundation of China(Grant No.2011ZF55015)the Basic and Frontier Technology Research Program of Henan Province,China(Grant Nos.112300410264 and 122300410162)the Cooperation Fund with Fudan University,China(Grant No.KL2011-01)the National Basic Research Program of China(Grant No.2011CB922004)
文摘We theoretically investigate the photonic band gap in one-dimensional photonic crystals with a graded multilayer structure. The proposed structure constitutes an alternating composite layer （metallic nanoparticles embedded in TiO2 film） and an air layer. Regarding the multilayer as a series of capacitance, effective optical properties are derived. The dispersion relation is obtained with the solution of the transfer matrix equation. With a graded structure in the composite layer, numerical results show that the position and width of the photonic band gap can be effectively modulated by varying the number of the graded composite layers, the volume fraction of nanoparticles and the external stimuli.
基金This work was financially supported by the Beijing Foundation of Natural Science, China(No. Z012013).
文摘Ordered macroporous titania photonic crystals （PCs） and photonic balls were fabricated by functional modified polymer colloidal crystals. The TiO2 PCs and balls formed through this method exhibit no cracks and lacunae in large areas on their surface and their inner structures.
基金Supported by the National Natural Science Foundation of China under Grant Nos 50872089,61077039 and 61377060the Research Grants Council of the Hong Kong Special Administrative Region of China under Grant No 11211014+1 种基金the Key Program for Research on Fundamental to Application and Leading Technology of Tianjin Science and Technology Commission of China under Grant No 11JCZDJC15500the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No 20100032110052
文摘Transmission spectra of triangular lattice photonic crystals milled in the top surface of an annealed proton- exchange waveguide are numerically simulated. The effects of the finite depth, conical shape, trapezoidal shape and hybrid shape of holes are theoretically analyzed. Due to the difficulty of milling high aspect-ratio cylindrical holes in lithium niobate （LiNbO3 ）, a compromised solution is proposed to improve the overlap between shallow holes and the waveguide mode, and useful transmission spectra with strong contrast and sharp band edges are achieved.
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Funded by the National Natural Science Foundation of China(No.51873167)the National Innovation and Entrepreneurship Training Program for College Students(No.S202010497024)。
文摘A thermal-responsive photonic crystal material was fabricated by forming an inverse opal nanocomposite hydrogel of poly(N-isopropylacrylamide)(IONHPNIPAm)within the interstitial space of a polystyrene photonic crystal template.In IONHPNIPAm,PNIPAm were physically cross-linked with two kinds of nanoparticles(carbon dots and laponite clays).The integration of carbon dots and laponite clays for physical crosslinking endowed IONHPNIPAm sufficient strength and self-healing property.IONHPNIPAm films can be completely peeled from the substrates to be utilized as an independent photonic crystal material.The structural color and optical diffraction of the IONHPNIPAm exhibits a rapid reversible change in response to external thermal stimuli due to its physical cross-linking feature.Moreover,the IONHPNIPAm shows clear fluorescence due to the introduction of carbon dots,which enables a convenient way for chemical detection(such as the detection of silver ions).This stimuli-responsive photonic crystal materials based on physically cross-linked inverse opal nanocomposite hydrogels with fast response and good mechanical stability are promising for applications in the fields of smart optical detectors,thermal-responsive sensors and chemical detectors.
文摘Group velocity （GV） of eigenmode is a crucial parameter to explain the extraordinary phenomena about light propagation in photonic crystals （PhCs）. To study relationships between group velocity and symmetry of PhCs, a new general expression of CV in PhCs made up of non-dispersive material is introduced. Based on this, the CVs of eigenmodes of PhCs, especially those of degenerate eigenmodes at highly symmetric points in the first Brillouin zone, are discussed. Some interesting results are obtained. For example, the summation of degenerate eigenmodes＇ CVs is invariant under the operations of wave vector K-group MK. In addition, some numerical results are presented to verify them.
基金Project supported by the National Natural Science Foundation of China (Grant No. 91121019)the National Basic Research Program of China (Grant No. 2013CB632105)
文摘An electrically driven, single-longitudinal-mode GaAs based photonic crystal （PC） ridge waveguide （RWG） laser emitting at around 850 nm is demonstrated. The single-longitudinal-mode lasing characteristic is achieved by introducing the PC to the RWG laser. The triangle PC is etched on both sides of the ridge by photolithography and inductive coupled plasma （ICP） etching. The lasing spectra of the RWG lasers with and without the PC are studied, and the result shows that the PC purifies the longitudinal mode. The power per facet versus current and current-voltage characteristics have also been studied and compared.
基金Project supported by the Key Science and Technology Research Project of Henan Province, China (Grant No. 1721023100107).
文摘To obtain the adjustable photonic crystals (PCs), we numerically investigate one-dimensional (1D) PCs with alternating VO2 and SiO2 layers through transfer matrix method. The dispersion relation agrees well with the transmittance obtained by the finite element calculation. Tunable band gaps are achieved with the thermal stimuli of VO2, which has two crystal structures. The monoclinic crystal structure VO2 (R) at low temperature exhibits insulating property, and the high temperature square rutile structure VO2 (M) presents metal state. Concretely, the bandwidth is getting narrower and red shift occurs with the higher temperature in VO2 (R)/SiO2 PCs structure. Based on the phase change characteristics of VO2, we can flexibly adjust the original structure as VO2 (R)/VO2 (M)/SiO2. By increasing the phase ratio of VO2 (R) to VO2 (M), the band gap width gradually becomes wider and blue shift occurs. The discrete layers of gradient composites on the dispersion of 1D PCs are also investigated, which enhances the feasibility in practical operation. Thus, our proposed thermal modulation PCs structure paves a new way to realize thermal tunable optical filters and sensors.
基金supported by National Natural Science Foundation of China(No.11875014)the Natural Science Foundation of Hebei Province(A2017201099)。
文摘Plasma photonic crystals(PPCs)are emerging as a powerful instrument for the dynamical control of the electromagnetic properties of a propagating wave.Here we demonstrate several one-dimensional(1 D)PPCs with uniquely designed superlattice structures,annular structures or with incorporation of the third material into the primitive unit cell.The influences of the properties of the third material as well as the structural configurations of suplerlattices on the transmittance characteristics of PPCs have been investigated by use of the finite element method.The optimal design strategy for producing PPCs that have more and larger band gaps is provided.These new schemes can potentially be extended to 2 D or 3 D plasma crystals,which may find broad applications in the manipulation of microwaves and terahertz waves.
基金Project supported by the National Basic Research Program of China （Grant No 001CB61040） and the Natural Science Foundation of Beijing, China （Grant No1032003）.
文摘We present a new type of optical filter with an ultra-narrow bandwidth and a wide field-of-view （FOV）. This kind of optical filter consists of one-dimensional photonic crystal （PC） incorporating an anomalous-dispersion-material （ADM） with, for instance, an anomalous dispersion of 6P3/2←6S1/2 hyperfine structure transition of a caesium atom. The transmission spectra of optical filters are calculated by using the transfer-matrix method. The simulation results show that the designed optical filter has a bandwidth narrower than 0.33GHz and a wide FOV of ±30°as well. The response of transmission spectrum to an external magnetic field is also investigated.
