Photonic Band Gap Properties Research Articles

Fabrication of multifunctional SnO_2 and SiO_2-SnO_2 inverse opal structures with prominent photonic band gap properties

We present here a simple two step infiltration and calcination involved technique to obtain high optical quality inverse opal structures of SiO2, SnO2 and SiO2-SnO2 binary oxide inverse opal structures. Scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction measurements are carried out to investigate the structural features of the opals. High resolution TEM measurements reveal the uniform distribution of SnO2 nanocrystals throughout the inverse opal matrix. Optical properties along with theoretical fitting reveal the interesting photonic band gap features of the opals with high optical quality as well as the high porosity of these structures. The well-known multifunctional properties of SnO2 like photorefractivity, low phonon energy for luminescent materials and gas sensing features show the advantages of these inverse opal structures can be favorable in the development of photonics and sensors.

A Shifted Waveguide Connector Combined with a Photonic Crystal Filter Designed by Transformation Optics

In this paper, transformation optics and photonic crystals have been introduced to design a shifted waveguide that can also be used as a filter. Instead of starting from an effectively homogeneous medium, we transform a regular photonic crystal into an elliptical one in physical space. Compared with a traditional waveguide, the simulations and calculations perfectly agree with the theoretical analytical model without any reflection and distortion. By taking advantage of the properties of photonic band gaps, the shifted waveguide can block some specific frequencies. We also composed a set of waveguide shifters without loss based on the proposed design. Full-wave electromagnetic simulations using detailed examples are performed to confirm the characteristics of the novel waveguide.

Properties of Photonic Band Gaps in Superconductor Multilayer Structure with Periodically Varying Ambient Temperature

The properties of the reflectance for a superconductor multilayer structure with periodically varying ambient temperature have been theoretically investigated by the transfer matrix method (TMM). From the numerical results, it has been shown that such system has the photonic band gap (PBG) properties of photonic crystals (PCs), so it can also be called superconductor photonic crystals (SPCs). It is found that the locations and bandwidths of PBGs can be modulated by the incident angle. The frequency ranges and central frequencies of PBGs can be tuned by the temperature and thickness of superconductor layer A (higher temperature superconductor layer), respectively. The bandwidths of PBGs can be notably enlarged with increasing the temperature of superconductor layer A. The frequency ranges of PBGs can be controlled by increasing the thickness of superconductor layer A, and the more PBGs appear. The damping coefficient of superconductor and the number of periods have little effect on the bandwidths of PBGs under low-temperature conditions. It is shown that this kind of SPCs has potential applications in filters, microcavities, and fibers, etc.

PROPERTIES OF ANISOTROPIC PHOTONIC BAND GAPS IN THREE-DIMENSIONAL PLASMA PHOTONIC CRYSTALS CONTAINING THE UNIAXIAL MATERIAL WITH DIFFERENT LATTICES

In this paper, the properties of anisotropic photonic band gaps (PBGs) in three-dimensional (3D) nomagnetized plasma photonic crystals (PPCs) composed of anisotropic dielectric (the uniaxial material) spheres immersed in uniform nomagnetized plasma background with various lattices including the diamond, face-centered- cubic (fcc), body-centered-cubic (bcc) and simple-cubic (sc) lattices, are theoretically investigated by the plane wave expansion (PWE) method. The equations for calculating the anisotropic PBGs in the flrst irreducible Brillouin zone are theoretically deduced. The anisotropic PBGs and a ∞atbands region can be obtained as the uniaxial material introduced into 3D PPCs. The PPCs with diamond lattices consisting of isotropic dielectric have the larger PBGs compared to PPCs doped by the uniaxial material since its low-symmetry structure. Furthermore, the PPCs with fcc, bcc, sc lattices will not exhibit a complete PBG unless the uniaxial material is introduced. The in∞uences of the ordinary-refractive index, extraordinary-refractive index, fllling factor and plasma frequency external magnetic fleld on the properties of anisotropic PBGs for 3D PPCs with fcc, bcc, sc lattices are investigated in detail, respectively, and some corresponding physical explanations are also given. The numerical results show that the anisotropy can open partial band gaps in 3D PPCs with fcc, bcc, sc lattices, and the complete PBGs can be obtained compared to 3D PPCs doped by the conventional isotropic dielectric. It also is shown that

Photonic band gaps of two-dimensional hexagon-lattice photonic crystals based on Taiji-shaped dielectric rods

We present a novel structure of two-dimensional (2D) hexagon-lattice photonic crystal with asymmetrical scatterers-Taiji-shaped scatterers. The properties of photonic band gap (PBG) and the influence of parameter on absolute photonic band gap are analyzed by plane wave expansion method. The calculation results demonstrate that the reduction of scatterer symmetry can produce an increase in the number of PBG and a broadening of PBG width for both TE and TM model, which is conducive to obtaining wider and more absolute PBG. By optimizing the parameters of structure, we obtain the widest absolute PBG 0.0541(ωa / 2πc) at ε = 17, R= 0.38 μm, r=0.36R, and θ = 0° and the maximum of 8 absolute PBGs at ε = 16, R=0.44, r=0.2R, and θ = 0°.

Photonic bandgap properties of one-dimensional superconducting photonic crystals containing metamaterials

Bandgap properties of one-dimensional superconducting photonic crystals containing metamaterials are investigated by the transfer matrix method. It is shown that the low-frequency band gap can also be present in this superconducting photonic crystal similar to the usual superconducting photonic crystal containing dielectric materials. The low-frequency band gap can be widened considerably when the suitable structure parameters are chosen. However, in certain structural parameters, the low-frequency band gap can not be found in this superconducting photonic crystal just as in one-dimensional dielectric-dielectric photonic crystal. The polarization properties and the influences of the operating temperature and the structure parameters of superconducting photonic crystals on the photonic band gap are also investigated in this paper.

Facile synthesis of ZnS nanobowl arrays and their applications as 2D photonic crystal sensors

Large-area ZnS nanobowl arrays with a monolayer inverse opal structure were synthesized facilely by nanosphere lithography at solution surface (NSLSS) through direct solution deposition. It was shown that the well-defined ZnS nanobowl arrays resulted from preferential deposition of ZnS at the polystyrene sphere–solution interface. Owing to the 2D periodic structure of the hexagonally ordered nanobowl arrays and the high refractive index of ZnS, the as-prepared ZnS nanobowl arrays showed intensive structural colors and tunable photonic band-gap properties. These ZnS nanobowl arrays are able to act as effective, fast-responsive 2D photonic crystal sensors based on the refractive index changes because of their easy accessibility for both solvents and analyte molecules. The as-prepared ZnS nanobowl arrays can be used as sensitive 2D photonic crystal sensors for fast detection of organic solvents and for visual oil sensing through color changes. After surface functionalization, the ZnS nanobowl arrays can be used as effective 2D photonic crystal biosensors for sensitive detection of avidin molecules with low detection limits (less than 100 pM) and broad working range.

Photonic band gaps in one-dimensional magnetized plasma photonic crystals with arbitrary magnetic declination

In this paper, the properties of photonic band gaps and dispersion relations of one-dimensional magnetized plasma photonic crystals composed of dielectric and magnetized plasma layers with arbitrary magnetic declination are theoretically investigated for TM polarized wave based on transfer matrix method. As TM wave propagates in one-dimensional magnetized plasma photonic crystals, the electromagnetic wave can be divided into two modes due to the influence of Lorentz force. The equations for effective dielectric functions of such two modes are theoretically deduced, and the transfer matrix equation and dispersion relations for TM wave are calculated. The influences of relative dielectric constant, plasma collision frequency, incidence angle, plasma filling factor, the angle between external magnetic field and +z axis, external magnetic field and plasma frequency on transmission, and dispersion relation are investigated, respectively, and some corresponding physical explanations are also given. From the numerical results, it has been shown that plasma collision frequency cannot change the locations of photonic band gaps for both modes, and also does not affect the reflection and transmission magnitudes. The characteristics of photonic band gaps for both modes can be obviously tuned by relative dielectric constant, incidence angle, plasma filling factor, the angle between external magnetic field and +z axis, external magnetic field and plasma frequency, respectively. These results would provide theoretical instructions for designing filters, microcavities, and fibers, etc.

Magnetically Tunable Terahertz Isolator Based on Structured Semiconductor Magneto Plasmonics

A tunable terahertz (THz) isolator based on a periodically structured semiconductor magneto plasmonics is proposed. The unique photonic band-gap and one-way transmission property of this structure with different magnetic fields and temperature are investigated in the THz regime. The numerical results show the proposed isolator has a bandwidth of 80 GHz with the maximum isolation of higher than 90 dB and a low insertion loss of 5%. The central operating frequency of this isolator can be broadly tuned from 1.4 to 0.9 THz by changing the external magnetic field from 0.6 to 1.6 Tesla at 195 K. This low-loss high isolation broadband nonreciprocal THz transmission mechanism has great potential applications in promoting the performances of THz application systems.

Properties of omnidirectional photonic band gap in one-dimensional staggered plasma photonic crystals

In this paper, the properties of the omnidirectional photonic band gap (OBG) realized by one-dimensional (1D) photonic crystals (PCs) with a staggered structure which is composed of plasma and isotropic dielectric layer have been theoretically studied by the transfer matrix method (TMM). From the numerical results, it has been shown that such OBG is insensitive to the incident angle and the polarization of electromagnetic wave (EM wave), and the frequency range and central frequency of OBG can be effectively controlled by adjusting the plasma frequency, the average thickness of plasma layer, the average thickness of dielectric layer and staggered parameters, respectively. The frequency range of OBG can be notably enlarged with increasing the plasma frequency, average thickness of plasma layer, respectively. Moreover, the bandwidth of OBG can be narrowed with increasing the average thickness of dielectric layer. Changing staggered parameters of dielectric and plasma layer means that the OBG can be tuned. It is shown that 1D plasma dielectric photonic crystals (PPCs) with such staggered structure have a superior feature in the enhancement of frequency range of OBG compared with the conventional 1D binary PPCs. This kind of OBG has potential applications in filters, microcavities, and fibers, etc.

Enhancement of Omnidirectional Photonic Bandgaps in One-Dimensional Superconductor–Dielectric Photonic Crystals with a Staggered Structure

In this paper, the properties of the omnidirectional photonic bandgap (OBG) realized by one-dimensional (1D) photonic crystals with a staggered structure which is composed of superconductor and isotropic dielectric have been theoretically investigated by the transfer matrix method (TMM). From the numerical results, it has been shown that such OBG is insensitive to the incident angle and the polarization of electromagnetic wave (EM wave), and the frequency range and central frequency of OBG can be tuned by the ambient temperature of system, the average thickness of superconductor layer, the average thickness of dielectric layer, and staggered parameters, respectively. The bandwidth of OBG can be notably enlarged with increasing average thickness and staggered parameter of superconductor layer. Moreover, the frequency range of OBG can be narrowed with increasing the average thickness, staggered parameter of dielectric layer, and ambient temperature, respectively. The damping coefficient of superconductor layer has no effect on the bandwidth of OBG under low-temperature conditions. It is shown that 1D superconductor–dielectric photonic crystals (SDPCs) have a superior feature in the enhancement of frequency range of OBG. This kind of OBG has potential applications in filters, microcavities, and fibers, etc.

Photonic Bandgap Properties of Photonic Crystal Fibers with the Triangular Nonair-Silica Structures

The study on the photonic crystal fibers becomes a new research field of fiber optics in recent years, and the bandgap properties of the photonic crystal fibers are the main different points different from those of the general optical fibers. This paper performs the analysis on the bandgap properties of the photonic crystal fibers with the triangular nonair-silica structures by use of the full-vector plane-wave expansion method, focusing on the effect of the dielectric materials filled in the holes on the existence of photonic bandgaps.

Level Set Photonic Quasicrystals with Phase Parameters

AbstractA systematic study of the photonic band gap (PBG) properties of 8‐, 10‐ and 12‐fold rotational symmetric quasicrystals (QCs) defined by level set equations with various phase parameters is reported. The optimized filling ratios corresponding to the largest PBGs for 19 types of QCs are found, which are useful for photonic QC fabrication design. The impact of filling ratio, rotational symmetry, and experimental fabrication parameters on the resultant PBGs are studied via PBG maps calculated by finite‐difference time‐domain (FDTD). Large area, high quality 8‐, 10‐, and 12‐fold quasicrystalline pattern fabrication using multiple exposure interference lithography (MEIL) is also demonstrated.

A facile method for the synthesis of highly monodisperse silica@gold@silica core–shell–shell particles and their use in the fabrication of three-dimensional metallodielectric photonic crystals

We report here (i) a method for the synthesis of highly monodisperse silica@gold@silica core–shell–shell (CSS) particles (<6% deviation in size) with coherent outer silica shells of directly tunable thickness and porosity, (ii) the fabrication of three unit cell thick (12 layers) metallodielectric photonic crystals (MDPCs) from these particles and (iii) their angle-resolved optical reflectance properties demonstrating the influence of dielectric contrast modification and metal plasmonic modes on photonic band gap properties. The synthetic route presented describes the use of two alkylamines, the first, 1,3-diaminopropane (DAP), as a surface manipulating agent, and the second, N,N-dimethyldodecylamine (DMDDA), as a catalyst for the outer silica shell formation, for the reproducible synthesis of monodisperse CSS particles avoiding the formation of the unwanted side-products such as core-free silica particles and aggregated particles with multiple cores. A rational chemical reaction mechanism describing the pathways involved in the formation of coherent silica shells, demonstrating the roles of both the amines, is proposed. The creation of partial wetting/de-wetting sites on gold nanoparticle surfaces by the adsorbed DAP molecules, the surface silanol modification by DAP and the slow hydrolysis–condensation reactions catalyzed by DMDDA are found to be responsible for the selective deposition of silica (heterogeneous nucleation) only onto the existing silica@gold core–shell particles leading to the formation of monodisperse CSS particles. The optical reflectance of the MDPC formed from these CSS particles shows an angle-dependent blue-shift that perfectly obeys the Bragg–Snell law predictions for photonic crystals. The dielectric contrast modification and the possible metal plasmonic mode-coupling in the MDPC also result in a high gap-to-midgap ratio (23%) as compared to the PC made of neat silica particles of comparable size (9%).

PROPERTIES OF OMNIDIRECTIONAL PHOTONIC BAND GAPS IN FIBONACCI QUASI-PERIODIC ONE-DIMENSIONAL SUPERCONDUCTOR PHOTONIC CRYSTALS

In this paper, the properties of the omnidirectional photonic band gap (OBG) realized by one-dimensional (1D) Fibonacci quasi-periodic structure which is composed of superconductor and isotropic dielectric have been theoretically investigated by the transfer matrix method (TMM). From the numerical results, it has been shown that this OBG is insensitive to the incident angle and the polarization of electromagnetic wave (EM wave), and the frequency range and central frequency of OBG cease to change with increasing Fibonacci order, but vary with the ambient temperature of system, the thickness of the superconductor, and dielectric layer, respectively. The bandwidth of OBG can be notably enlarged with increasing the superconductor thickness. Moreover, the frequency range of OBG can be narrowed with increasing the thickness of dielectric layer and ambient temperature. The damping coe-cient of superconductor layers has no efiect on the frequency range of OBG under low- temperature conditions. It is shown that Fibonacci quasi-periodic 1D superconductor dielectric photonic crystals (SDPCs) have a superior feature in the enhancement frequency range of OBG. This kind of OBG has potential applications in fllters, microcavities, and flbers, etc.

Metallic photonic crystals for terahertz tunable filters

We have investigated the photonic band gap and transmission properties of metallic photonic crystals (PCs) filled with liquid crystal (LC) in the terahertz region by using the finite element method and the finitedifference time-domain method. The calculations on the LC-filled metallic PC and metallic PC waveguide demonstrated that they can realize low-loss broadband terahertz tunable filters, which have a tunable range of about 110 GHz and extinction ratio larger than 35 dB. Moreover, the 3 dB bandwidths of the filters keep constant. The designed filters based on the metallic PC can greatly improve the performances in terms of loss, bandwidth and tunable region compared to those based on the LC-filled dielectric PC.

Transmission properties of Fibonacci quasi-periodic one-dimensional superconducting photonic crystals

The transmission properties of Fibonacci quasi-periodic one-dimensional photonic crystals (1DPCs) containing superconducting material are theoretically investigated based on the transfer matrix method. It is shown that the 1DPCs can possess a same photonic band gap property as the periodic structure superconducting PC. The results of transmittance spectra show that the cutoff frequency can be manipulated through the thicknesses of the superconductor and dielectric layers as well as the ambient temperature of the system. It is observed that the shift of cutoff frequency becomes more noticeable by adjusting the thickness of the superconductor layer than that of the dielectric one. Furthermore, the cutoff frequency becomes very sensitive when the system temperature is tuned to close vicinity of the critical temperature of the superconductor.

Photonic bandgaps of different unit cells in the basic structural unit of germanium-based two-dimensional decagonal photonic quasi-crystals

Based on the infrared optical material germanium, in the basic structural unit of a two-dimensional decagonal photonic quasi-crystal, photonic bandgaps of four square unit cells with a scattering radius in the range of [0,0.3a] have been calculated within two cases of construction (i.e., air cylinders arranged in germanium and germanium cylinders arranged in air) by using the plane wave expansion method. In considering the Bragg-like scattering effect in two-dimensional photonic quasi-crystals as the elastic collision in physics, we put forward the photonic bandgap impact function F=q(1)q(2)q(3)επr(2) for the first time, to the best of our knowledge. A certain unit cell structure shares some similar photonic bandgap properties with a periodic structure. For a certain structure of the unit cell, the center frequency change trends of the photonic bandgap and the type of photonic bandgap generated are not related with the period of the photonic crystal, but with the relative dielectric constant and the construction, respectively. Different unit cell structures own different photonic bandgap structures. This occurs because the high degree of rotational symmetry of the quasi-periodic structure and weak long-range order of the basic structural unit lead to different Bragg-like scattering effects within the unit cell structures.

Photonic density of states of two-dimensional quasicrystalline photonic structures

A large photonic band gap (PBG) is highly favorable for photonic crystal devices. One of the most important goals of PBG materials research is identifying structural design strategies for maximizing the gap size. We provide a comprehensive analysis of the PBG properties of two-dimensional (2D) quasicrystals (QCs), where rotational symmetry, dielectric fill factor, and structural morphology were varied systematically in order to identify correlations between structure and PBG width at a given dielectric contrast (13:1, Si:air). The transverse electric (TE) and transverse magnetic (TM) PBGs of 12 types of QCs are investigated (588 structures). We discovered a 12$mm$ QC with a 56.5% TE PBG, the largest reported TE PBG for an aperiodic crystal to date. We also report here a QC morphology comprising ``throwing star''-like dielectric domains, with near-circular air cores and interconnecting veins emanating radially around the core. This interesting morphology leads to a complete PBG of \ensuremath{\sim}20% , which is the largest reported complete PBG for aperiodic crystals.

Transmission Properties of Thue-Morse Quasi-Periodic 1D Superconducting Photonic Crystals

The transmission properties of Thue-Morse quasi-periodic one-dimensional photonic crystals (1DPCs) containing superconducting material are theoretically investigated based on the transfer matrix method. It is shown that the 1DPCs can possess a same photonic band gap property as the periodic structure superconducting PC. The results of transmittance spectra show that the cutoff frequency can be manipulated through the thicknesses of the superconductor and dielectric layers as well as the ambient temperature of the system. It is observed that the shift of cutoff frequency becomes more noticeable by adjusting the thickness of the superconductor layer than that of the dielectric one. Furthermore, the cutoff frequency becomes very sensitive when the system temperature is tuned to close vicinity of the critical temperature of the superconductor.