Photonic Band Gap Properties Research Articles

Theoretical Analysis of Band Gap of 2-D Square Photonic Crystals Fabricated by Dual-Step Dual-Team Holographic Method

The dual-step dual-team holographic method to fabricate square lattices is proposed. The effect of intensity threshold was analyzed by calculating the intensity spatial distribution. The photonic band gap properties of two-dimensional square lattice fabricated by holographic lithography are investigated numerically. The influences of intensity threshold and dielectric contrast on photonic gap are comprehensively studied by plane wave expansion method. Calculations of band structure as a function of the intensity threshold show that the full photonic band gap does not increase monotonically with dielectric contrast ratio, but has a peak value instead by studying the relation between the complete PBG and the dielectric contrast.

Photonic bandgap plasmonic waveguides

A type of a plasmonic waveguide has been proposed featuring an "open" design that is easy to manufacture, simple to excite and offers convenient access to a plasmonic mode. Optical properties of photonic bandgap (PBG) plasmonic waveguides are investigated experimentally by leakage radiation microscopy and numerically using the finite element method confirming photonic bandgap guidance in a broad spectral range. Propagation and localization characteristics of a PBG plasmonic waveguide have been discussed as a function of the wavelength of operation, waveguide core size, and the number of ridges in the periodic reflector for fundamental and higher order plasmonic modes of the waveguide.

Temperature-modified photonic bandgap in colloidal photonic crystals fabricated by vinyl functionalized silica spheres

A thermal annealing procedure for fine modifying the photonic bandgap properties of colloidal photonic crystals was described. The colloidal photonic crystals were assembled from monodisperse vinyl functionalized silica spheres by a gravity sedimentation process. The samples diffract light following Bragg's law combined with Snell's law. By annealing the sample at temperatures in the range of 60–600 °C, the position of its stop band shifted from 943 to 706 nm. It had more than 25% blue shift. In addition, the annealing temperature and the Bragg peak values have a linear relationship in the 120–440 °C range. Fourier transform infrared (FT-IR) spectra and thermo-gravimetric analysis (TGA) curves of vinyl functionalized silica spheres confirmed the above results. The effects provide a simple and controllable method for modifying the photonic bandgap properties of colloidal photonic crystals.

Photonic gap vanishing in one-dimensional photonic crystals with single-negative metamaterials

The properties of photonic band gap in one-dimensional photonic crystals composed of single-negative metamaterials are studied theoretically. Our study shows that the photonic gap will vanish at a certain incident angle when both the phase-match and impedance-match conditions are satisfied simultaneously, suggesting that the bandwidth and location of the photonic gap are strongly dependent on the incident angle and polarization. However, the photonic gap will not vanish and may become insensitive to the incident angle when the two match conditions cannot be met. Our study also shows that losses in metamaterials have little effect on the properties of the photonic gap.

Absolute photonic band gaps of two-dimensional square-lattice photonic crystals with Taiji-shaped dielectric rods

A novel structure of two-dimensional (2D) square-lattice photonic crystal (SLPC) composed of Taiji-shaped dielectric rods imbedded in air is constructed and the properties of absolute photonic band gap (PBG) are theoretically analyzed in both the number and width by Plane Wave Expansion Method (PWM). By comparing the absolute PBGs in 2D SLPCs consisting of four shapes of rods with different symmetries (circle, button, semicircle and Taiji) at the same filling ratio, we find that both the number and width of absolute PBG significantly increase with the breaking of scatterer's symmetry, and the Taiji-shaped rods with the poorest symmetry can attain both the most number and the largest width of absolute PBGs. Additionally, we also study the influence of dielectric constant ε and three geometric parameters of Taiji-shaped scatterer on the absolute PBG and discover that the SLPC with Taiji-shaped rods can generate at most nine absolute PBGs and the largest absolute PBG with the width 0.0485 (ωa/2πc).

Photonic band gap and upconversion emission properties of Yb, Er co-doped lead lanthanum titanate inverse opal photonic crystals

Upconversion (UC) emission properties of Yb, Er co-doped lead lanthanum titanate inverse opal photonic crystals were investigated. The results showed that the photonic band gap has a significant influence on the upconversion emission of Yb, Er co-doped lead lanthanum titanate inverse opal photonic crystals. Significant suppression of the upconversion emission was detected if the photonic band gap overlapped with the Er3+ ions emission band.

Formation of Infrared Regions of Transparency in One-Dimensional Silicon Photonic Crystals

The optical properties of three-component one-dimensional photonic crystal (1-D PC) structures were investigated by modeling them as two-component PCs with an additional regular <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> -layer, using the gap map approach and the transfer matrix method. Numerical results demonstrate that the introduction of the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> -layer affects the properties of the high-order photonic band gaps, replacing them with transmission bands and creating regions of transparency over certain wavelength ranges. For the first time, a map of the transmission bands for a three-component 1-D PC was generated. This map constitutes a unique design tool for infrared optical filters for silicon-based photonic integrated circuits.

Systematic progressions of core-shell polygon containing tiling patterns in melts of 2nd generation dendritic miktoarm star copolymers

Dissipative particle dynamics simulations are used to investigate the self-assembly of generic 2nd generation dendritic 3-miktoarm star copolymers. These molecules can be conceptually conceived as the attachment of three ABC 3-miktoarm terpolymers to a common junction. In analogy to ABC 3-miktoarm star terpolymers the resulting morphologies show a number of cylindrical structures displaying a systematic progression through various 2D Archimedean tiling patterns as the molecular volume fractions are altered. The insertion of a variably sized junction region allows the controlled formation of tiling patterns where one polygonal component is a core-shell cylinder. A rich phase diagram is presented when invoking asymmetric interaction parameters indicating the possibility of jumping between these tiling patterns in a controllable way. We discuss how these core-shell containing tiling patterns potentially constitute self-assembled soft materials combining well-defined directional charge carriage and photonic band gap properties.

Biotemplating routes to three-dimensional photonic crystals

The strikingly colorful world of insects is in large part the result of light interacting with periodically organized biopolymeric structures incorporated into wings, hairs and exoskeletons. Such structural colors have recently gained tremendous interest as photonic crystals with their ability to control the behavior of light in revolutionary new ways. This highlight article reviews recent developments in employing biological structures as unique templates for the fabrication of inorganic photonic crystals. Different biotemplating methods, including atomic layer deposition, conformal-evaporated-film-by-rotation and sol–gel chemistry, are introduced and discussed. Under optimized conditions these methods produce high-fidelity inorganic replica structures with improved sensing, light emission and photonic band gap properties.

Photonic bandgap under irradiation of a Gaussian beam

The transfer matrix of a dielectric slab under propagation of a Gaussian beam was formulated. The derived matrix was applied for a one-dimensional photonic crystal (1DPC) structure and the transmittance spectrum and photonic bandgap (PBG) properties were investigated. An r-dependent (r is the radial coordinate of the Gaussian beam) PBG was obtained. With the increase of r, a redshift and a decrease in the PBG are observed. Higher PBGs experience more shift. Also properties of the photonic crystal (PC) structure with defect layer were investigated and displacement to red and decrease of the defect mode peak height, with an increase of r, were observed. The extra optical path that the outer rays travel due to the oblique propagation compared to the central ray in a Gaussian beam is responsible for these effects. For long Rayleigh ranges our results for the Gaussian beam were the same as that for plane wave.

Kinetics of Stop-Flow Atomic Layer Deposition for High Aspect Ratio Template Filling through Photonic Band Gap Measurements

Atomic layer deposition (ALD) is shown as a unique method to produce high aspect ratio (AR) nanostructures through conformal filling and replication of high AR templates. The stop-flow process is often used as an alternative to the conventional continuous flow process to obtain high step coverage. However, there is a need for understanding the deposition kinetics and optimizing the deposition process to fabricate defect-free nanostructures. In this Article, TiO2 ALD in high AR self-assembled opal photonic crystal templates was performed in stop-flow fill−hold−purge process in comparison with continuous flow pulse−purge process. Photonic band gap properties of opal templates were characterized and compared with simulated band diagrams for quantitative investigation of filling kinetics and the effect of shrinking pore size on filling uniformity. Γ−L bands in the transmittance spectra of ALD-infiltrated opals accurately represented the depth profile of the depositions without the need for expensive sample preparation techniques and characterization tools. It was found that the stop-flow process attains higher Knudsen flow rates of precursor gases, thereby achieving homogeneous and complete filling at considerably lower cycle time.

Fabrication of three‐dimensional photonic crystals in quantum‐dot‐based materials

AbstractControlling spontaneous emission (SE) is of fundamental importance to a diverse range of photonic applications including but not limited to quantum optics, low power displays, solar energy harvesting and optical communications. Characterized by photonic bandgap (PBG) property, three‐dimensional (3D) photonic crystals (PCs) have emerged as a promising synthetic material, which can manipulate photons in much the same way as a semiconductor does to electrons. Emission tunable nanocrystal quantum dots (QDs) are ideal point sources to be embedded into 3D PCs towards active devices. The challenge however lies in the combination of QDs with 3D PCs without degradation of their emission properties. Polymer materials stand out for this purpose due to their flexibility of incorporating active materials. Combining the versatile multi‐photon 3D micro‐fabrication techniques, active 3D PCs have been fabricated in polymer‐QD composites with demonstrated control of SE from QDs. With this milestone novel miniaturized photonic devices can thus be envisaged.

Mid infrared band gap properties of 3-dimensional silicon inverse opal photonic crystal

By the solvent vaporization convection self-assembly method, 1.86 μm silica microspheres were assembled into a colloidal crystal template with long-range order. High refractive index silicon was then filled in the voids of the silica template by the low pressure chemical vapor deposition method. A 3-dimensional silicon inverse opal photonic crystal was obtained with a photonic band gap simulated by a plane wave expansion method. Its micro modality and photonic band gap properties were characterized by scanning electron microscopy and Fourier transform IR spectrometer. There was a good agreement between the measured spectra and the simulated results. The tilt-angle reflectance spectra showed that an obvious reflection peak at 3319 nm stayed in existence with different incidence directions. This result proved that silicon inverse opal has a complete photonic band gap in the mid infrared range. This study opens up an opportunity to create Si-based photonic crystal devices for atmosphere mid infrared photodetection.

Effect of defects outside the centre on dispersive properties of photonic band gap guiding photonic crystal fibers

The dispersion properties of optical wave in photonic band gap guiding photonic crystal fibers (PBG-PCF) were analyzed by the finite differential time domain method. The result demonstrates that: the point defects and the dislocation of air holes make the zero-dispersion-point move to the long-wavelength side, but the change of the shape of the air columm makes it move in the opposite direction. All kinds of defects make the dispersion curves flatten.

Fabrication of silicon inverse opal photonic crystal with a complete photonic band gap in mid infrared range and its optical properties

SiO2 colloidal crystal template was fabricated by the solvent vaporization convection self-assembly method. The low pressure chemical vapor deposition method was then used to fill the voids of the silica colloidal crystal template with high refractive index silicon, thus silicon inverse opal photonic crystal was obtained. The modality structure silicon inverse opal was characterized by scanning electron microscopy. Its photonic bandgap structure was calculated based on plane wave expansion method. Its photonic bandgap properties were characterized by Fourier transform infrared spectroscopy. The results showed that silicon is homogeneously distributed inside the voids of silica template. The wavelength and bandwidth of photonic bandgap measured by microscopic infrared spectrometer agree with the calculated one. The tilt-angle reflectance spectra along the different incidence angles showed that the refection peaks with the band center wavelength of 3319 nm always existed. This result proved that silicon inverse opal has the complete photonic bandgap. The bandgap lies in the range of mid infrared atmosphere window.

Realization of silicon nanopillar arrays with controllable sidewall profiles by holography lithography and a novel single-step deep reactive ion etching

AbstractA simple and efficient approach for fabricating silicon nanopillar arrays with a high aspect ratio and controllable sidewall profiles has been developed by using holographic lithography and a novel single-step deep reactive ion etching. During the etching process, scalloping of the sidewalls can be avoided while reserving the high mask selectivity and high etching rate. Besides, the sidewall angle of resultant patterns can be adjusted by tuning the composition of the gas mixture of single-step DRIE process. We further fabricate a tapered silicon nanopillar array and observe its photonic bandgap property. We believe that the good optical performance of this tapered silicon nanopillar array realized by the proposed approach shows the promising of this process for various applications.

10.1007/s11490-008-3014-6

The photonic bandgap properties of periodic interfaces between noble metals and dielectrics exhibiting third-order optical nonlinearity are investigated. Some device configurations aimed at obtaining all-optical switching around 1500 nm are proposed, based either on the excitation of propagating surface plasmons at a sinusoidally modulated interface or on the back-reflection properties of a sawtooth-modulated metal-dielectric interface under normal incidence of the radiation. In the second case, 35% switching of 15-ps 5-nJ input pulses can be obtained using polydiacetylenes as the nonlinear dielectric.

Millimeter Wave Control Using TiO2 Photonic Crystal with Diamond Structure Fabricated by Micro-Stereolithography

The diamond photonic crystals with the periodic arrangement of high dielectric constant (ε=100) were fabricated, and photonic band gap properties in the millimeter waveguides were investigated. Acrylic diamond lattice structures with TiO2 dispersion at 40 vol. % were fabricated by Micro-stereolithography. The forming accuracy was 10m. After sintering process, TiO2 diamond lattice structures are obtained. The relative density reached 96%. The millimeter wave transmittance properties were measured with network analyzer and W-band millimeter waveguide. The band gap was measured between 90 GHz and 110 GHz in the Γ-X &lt;100&gt; direction, which was well agreed with the results calculated by the plane wave expansion method and simulated by the Transmission Line Modeling method.

Complex 2D photonic crystals with analogue local symmetry as 12-fold quasicrystals

We construct fourteen complex periodic two-dimensional (2D) photonic structures with different structural symmetries by arranging the small portions of a 12-fold quasicrystal on square or hexagonal lattices. The corresponding reciprocal lattices confirm that all of them demonstrate the 12-fold-like characteristics due to the analogue short-range arrangements. We then investigate their photonic bandgap properties at different dielectric contrast levels (dielectric rods in air background). Our results suggest that all structures possess analogue transverse magnetic (TM) gaps in both Si and glass photonic crystals due to the similarity of their local geometries. However, the arrangements of the basic elements, total symmetries, and the coupling between the local and the lattice symmetries have greater impact on the glass photonic crystals, which show much larger deviation of gap sizes from different structures. Furthermore, we find that the minimal dielectric contrast to achieve the TM gap in the complex lattices (dielectric-in-air) can be as low as epsilon = 1.44, whereas the inverse structures may open a 2D complete gap in silicon nitride (epsilon = 4.1).

Analysis of multiple reflections in hybrid photonic crystal multimode interference coupler

In this paper the analysis of multiple reflections in photonic crystal (PhC) multimode interference (MMI) couplers using eigen-mode expansion method is presented. The analysis is conducted on a hybrid PhC structure which consisted of 1-D PhC multimode waveguide sandwiched between 2-D PhC input/output waveguides. In PhC multimode waveguide, where the mechanism of wave confinement is not due to total internal reflection but due to photonic bandgap properties, the reflectivity at 2-D PhC facet wall would be very large for all the guided modes in the waveguide when ever the image formed due to MMI effect does not coincides with the output access waveguide.