Photonic Bands

Haus, Joseph W.; Sözüer, H. Sami; Inguva, Ramarao

doi:10.1080/09500349214552061

Cited by 39 publications

(23 citation statements)

References 15 publications

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“…When combined with methods that allow control over the orientation and symmetry of two-and three-dimensional colloidal crystals [23,24] the particle deformation technique will also provide for an important additional degree of freedom to tune optical phenomena in (thin) photonic crystals. In fact, optical bandstructure calculations show that, for a given particle asymmetry, photonic crystals composed of spheroids can have larger bandgaps than those composed of spheres [25]. Also, it has been shown that a single oblate micro-resonator shows strongly improved lasing properties compared to a spherical resonator [11].…”

Section: Anisotropic Deformation Of Three-dimensional Colloidal Crystalsmentioning

confidence: 99%

Colloidal assemblies modified by ion irradiation

Snoeks

Blaaderen

Dillen

et al. 2001

Nuclear Instruments and Methods in Physics Research Section B:

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Spherical SiO 2 and ZnS colloidal particles show a dramatic anisotropic plastic deformation under 4 MeV Xe ion irradiation, that changes their shape into oblate ellipsoidal, with an aspect ratio that can be precisely controlled by the ion¯uence. The 290 nm and 1.1 lm diameter colloids were deposited on a Si substrate and irradiated at 90 K, usinḡ uences in the range 3 Â 10 13 ±8 Â 10 14 cm À2 . The transverse particle diameter shows a linear increase with ion¯uence, while the longitudinal diameter shrinks; the particle volume remains constant. Size aspect ratios up to 3.1 are achieved. Applications of the ion beam deformation technique are shown in studies of liquid crystalline colloidal ordering, selfassembled two-dimensional colloidal lithographic masks for thin-®lm deposition, and in tuning the optical properties of three-dimensional colloidal crystals. Ó

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Section: Anisotropic Deformation Of Three-dimensional Colloidal Crystalsmentioning

confidence: 99%

Colloidal assemblies modified by ion irradiation

Snoeks

Blaaderen

Dillen

et al. 2001

Nuclear Instruments and Methods in Physics Research Section B:

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“…[3,4] As suggested by computational studies, this degeneracy can be broken using shape-anisotropic [5] or dielectrically anisotropic [6] colloidal particles as building blocks.…”

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confidence: 98%

Fabrication of 3D Photonic Crystals of Ellipsoids: Convective Self‐Assembly in Magnetic Field

et al. 2009

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In photonic crystals, two materials with different refractive indexes alternate with a specific periodicity on the opticalwavelength scale. Analogous to the band-gap for electrons in semiconductors, the spatially periodic structure in photonic crystals results in a forbidden stop-band for a particular spectral range of photons, the so-called photonic band-gap. Since being first proposed by Yablonovich and John, [1,2] photonic crystals have been desired to give complete photonic band-gap in the optical regime. In other words, within a specific range of frequencies photons should not be allowed to propagate in all three dimensions inside photonic crystals. Because of the optical scale of the periodicity in refractive index, the fabrication of photonic crystals with complete photonic band-gaps in the optical regime remains a challenge. Physical top-down approaches, including lithographic techniques starting from bulk materials, have proven their efficacy in the long-wavelength radar range, but are difficult to extend to the optical spectrum. Chemical bottom-up techniques, for example self-assembly of highly monodisperse and spherical colloidal particles, offer a viable alternative based on the combined ease of fabrication and low cost. Such photonic crystals from highly ordered colloidal particles are also known as artificial opals. However, in the crystallization of spherical colloids, only two most-stable crystal structures with high filling fraction have been obtained (for face-centered cubic, FCC, and for random hexagonal closed packing, RHCP).It has been suggested by previous studies that for an FCC lattice consisting of colloidal spheres there only exists a pseudo photonic band-gap in the photonic band structure, no matter how high the dielectric contrast, because of a symmetry-induced degeneracy at the W-or U-point of the band structure. [3,4] As suggested by computational studies, this degeneracy can be broken using shape-anisotropic [5] or dielectrically anisotropic [6] colloidal particles as building blocks.Early research in this direction mainly focused on the deformation of colloidal building blocks from spheres to ellipsoids after their being self-assembled into colloidal crystals. This ''post-crystallization treatment'' includes high-energy ion irradiation [7] and uniaxial mechanical stretching, [8,9] leading to colloidal crystals with ellipsoidal silica (SiO 2 ), zinc sulfide (ZnS), and polystyrene (PS) optical atoms. However, these deformation strategies applied on prefabricated colloidal crystals may cause the nonuniform deformation in different parts of the photoniccrystal film, or even to the destruction of the whole periodic superlattice. Direct self-assembly of nonspherical colloidal particles has been studied as an alternative strategy. Polystyrene ellipsoids were used as building blocks for direct self-assembly. The lack of long-range order indicated the difficulty of organizing nonspherical colloids into 3D crystalline lattices.[9] In recent years, Liddell et al. demonstrated the fabrication ...

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“…These ideas rely on the existence of a photonic band gap-a frequency region in which light propagation is forbidden. The region well below the gap received much less attention [7][8][9][10][11][12]. Here the wavelength is much greater than the lattice period; hence light "sees" a homogeneous medium.…”

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confidence: 99%

Photonic Crystal Optics and Homogenization of 2D Periodic Composites

1999

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We study the long-wavelength limit for an arbitrary photonic crystal (PC) of 2D periodicity. Light propagation is not restricted to the plane of periodicity. We proved that 2D PC's are uniaxial or biaxial and derived compact, explicit formulas for the effective ("principal") dielectric constants; these are plotted for silicon-air composites. This could facilitate the custom design of optical components for diverse spectral regions and applications. Our method of "homogenization" is not limited to optical properties, but is also valid for electrostatics, magnetostatics, dc conductivity, thermal conductivity, etc. Thus our results are applicable to inhomogeneous media where exact, explicit formulas are scarce. Our numerical method yields results with unprecedented accuracy, even for very large dielectric contrasts and filling fractions. [S0031-9007 (98)08154-X] PACS numbers: 42.70.Qs, 41.20.Jb, 42.25.LcPhotonic crystals (PC's) are arrays of dielectric materials with one-, two-, or three-dimensional periodicity. Since the suggestion [1] that PC's may be useful for controlling light emission, their properties have been researched intensively [2,3]. Recently, it was proposed that PC's could advance photonic information technology [4][5][6]. These ideas rely on the existence of a photonic band gap-a frequency region in which light propagation is forbidden. The region well below the gap received much less attention [7][8][9][10][11][12]. Here the wavelength is much greater than the lattice period; hence light "sees" a homogeneous medium. This situation is analogous to light propagation in natural crystals, whose optical properties like birefringence are described in crystal optics [13]. We studied analytically, for the first time, propagation in an arbitrary direction in space for a 2D PC.

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Photonic Bands

Cited by 39 publications

References 15 publications

Colloidal assemblies modified by ion irradiation

Colloidal assemblies modified by ion irradiation

Fabrication of 3D Photonic Crystals of Ellipsoids: Convective Self‐Assembly in Magnetic Field

Photonic Crystal Optics and Homogenization of 2D Periodic Composites

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