Spontaneous transition of one-dimensional plasma photonic crystal's orientation in a dielectric barrier discharge

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.

Photonic Band Modulation in a Two-Dimensional Photonic Crystal with a One-Dimensional Periodic Dielectric Background

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,

Reconfigurable(4, 6^(2)) and(4, 8^(2)) Archimedean plasma photonic crystals in dielectric barrier discharge

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.

Design of(GO/TiO2)N one-dimensional photonic crystal photocatalysts with improved photocatalytic activity for tetracycline degradation

(GO/TiO2)N(GO represents graphene oxide,and N represents the period number of alternate superposition of two dielectrics)onedimensional photonic crystal with different lattice constants was prepared via the sol–gel technique,and its transmission characteristics for photocatalysis were tested.The results show that the lattice constant,filling ratio,number of periodic layers,and incident angle had effects on the band gap.When the lattice constant,filling ratio,number of periodic layers,and incident angle were set to 125 nm,0.45,21,and 0°,respectively,a gap width of 53 nm appeared at the central wavelength(322 nm).The absorption peak of the photocatalyst at 357 nm overlapped the blue edge of the photonic band gap.A slow photon effect region above 96%reflectivity appeared.The degradation rate of tetracycline in(GO/TiO2)N photonic crystal was enhanced to 64%within 60 min.Meanwhile,the degradation efficiency of(GO/TiO2)N one-dimensional photonic crystal was effectively improved compared with those of the GO/TiO2 composite film and GO/TiO2 powder.

Comparative Study of the One Dimensional Dielectric and Metallic Photonic Crystals

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.

Transmission spectra characteristics of 1D photonic crystals with complex dielectric constant

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.

The features of band structures for woodpile three-dimensional photonic crystals with plasma and function dielectric constituents

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.

Description and reconstruction of one-dimensional photonic crystal by digital signal processing theory

A method of describing one-dimensional photonic crystals （1DPCs） based on Z-domain digital signal processing theory is presented. The analytical expression of the target band gap spectrum in the digital domain is obtained by the autocorrelation of its impulse response. The feasibility of this method is verified by reconstructing two simple 1DPC structures with a target photonic band gap obtained by the traditional transfer matrix method. This method provides an effective approach to function-guided designs of interference-based band gap structures for photonic applications.

Controllable and tunable plasma photonic crystals through a combination of photonic crystal and dielectric barrier discharge patterns

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.

Existing conditions of full bandgaps and absolute negative refraction in metallic-dielectric photonic crystal

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.

Controlling the Bandgaps of One-Dimensional TiO2/SiO2, TiO2/SnO2, and SiO2/SnO2 Photonic Crystals Using the Transfer Matrix Method

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 TiO2/SiO2, TiO2/SnO2, SiO2/SnO2, 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 TiO2/SiO2 and SiO2/SnO2, the edges became sharper and wider and the photonic bandgap width increased. Moreover, we demonstrated that PhCs with significantly thick TiO2/SiO2 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.

Study on the Reflection Spectra of One Dimensional Plasma Photonic Crystals Having Exponentially Graded Materials

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.

Band gaps structure and semi-Dirac point of two-dimensional function photonic crystals

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.

Fabrication of high-quality colloidal photonic crystals with sharp band edges for ultrafast all-optical switching

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.

Flexible one-dimensional photonic crystal films composed of chalcogenide glass and water-soluble polymer for curvature sensing

Curvature sensing plays an important role in structural health monitoring,damage detection,real-time shape control,modification,etc.Developing curvature sensors with large measurement ranges,high sensitivity,and linearity remains a major challenge.In this study,a curvature sensor based on flexible one-dimensional photonic crystal(1D-PC)films was proposed.The flexible 1D-PC films composed of dense chalcogenide glass and water-soluble polymer materials were fabricated by solution processing.The flexible 1D-PC film curvature sensor has a wide measurement range of 33-133 m-1and a maximum sensitivity of0.26 nm/m^(-1).The shift of the transmission peak varies approximately linearly with the curvature in the entire measurement range.This kind of 1D-PC film curvature sensor provides a new idea for curvature sensing and measurement.

Tunable triangular and honeycomb plasma structures in dielectric barrier discharge with mesh-liquid electrodes

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.

Spectroscopy and carrier dynamics of one-dimensional nanostructures

In recent years,one-dimensional(1D)nanomaterials have raised researcher's interest because of their unique structur-al characteristic to generate and confine the optical signal and their promising prospects in photonic applications.In this re-view,we summarized the recent research advances on the spectroscopy and carrier dynamics of 1D nanostructures.First,the condensation and propagation of exciton-polaritons in nanowires(NWs)are introduced.Second,we discussed the properties of 1D photonic crystal(PC)and applications in photonic-plasmonic structures.Third,the observation of topological edge states in 1D topological structures is introduced.Finally,the perspective on the potential opportunities and remaining chal-lenges of 1D nanomaterials is proposed.

Size effect on light propagation modulation near band edges in one-dimensional periodic structures

Periodic photonic structures can provide rich modulation in propagation of light due to well-defined band structures.Especially near band edges,light localization and the effect of near-zero refractive index have attracted wide attention.However,the practically fabricated structures can only have finite size,i.e.,limited numbers of periods,leading to changes of the light propagation modulation compared with infinite structures.Here,we study the size effect on light localization and near-zero refractive-index propagation near band edges in one-dimensional periodic structures.Near edges of the band gap,as the structure's size shrinks,the broadening of the band gap and the weakening of the light localization are discovered.When the size is small,an added layer on the surface will perform large modulation in the group velocity.Near the degenerate point with Dirac-like dispersion,the zero-refractive-index effects like the zero-phase difference and near-unity transmittance retain as the size changes,while absolute group velocity fluctuates when the size shrinks.

Investigation of one-dimensional Si/SiO_2 photonic crystals for thermophotovoltaic filter

The spectral control is widely incorporated with the thermophotovoltaic (TPV) technology to improve the optical-electric conversion efficiency of the whole sys- tem. In order to match with GaSb photovoltaic cell, an 8-layer one-dimensional photonic crystals (PC) filter structure was designed as quarter-wave periodic structure by selecting silicon (Si) and silicon dioxide (SiO2) as candidate materials. The multilayer Si/SiO2 structure was developed for the matching filter to simulta- neously realize the optimal matching with the spectral distribution of the high temperature emitter and the quantum efficiency of GaSb cell. The physical vapor deposition (PVD) method was used to fabricate the optical filter and the normal incidence optical property of the filter was measured within the spectral range from 0.7 to 3.3 μm. These experimental data were used to predict the spectral control performance in a TPV system. Finally, temperature performance experiments were carried out to establish its withstanding performance in high temperature envi- ronment.

The effect of array periodicity on the filtering characteristics of metal/dielectric photonic crystals

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.