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The Bruggeman homogenization formalism was used to numerically investigate the dielectric properties of a columnar thin film (CTF) made from vanadium dioxide. For visible and near-infrared wavelengths, the CTF is electromagnetically…

Optics · Physics 2025-04-08 Tom G. Mackay , Akhlesh Lakhtakia

Two different formalisms for the homogenization of composite materials containing ellipsoidal inclusions based on Bruggeman's original formula for spherical inclusions can be found in the literature. Both approximations determine the…

Optics · Physics 2013-09-13 Daniel Schmidt , Mathias Schubert

The theory describing the far-field emission from a dipole source embedded inside a chiral sculptured thin film (CSTF), based on a spectral Green function formalism, was further developed to allow for infiltration of the void regions of the…

Optics · Physics 2015-05-20 Siti S. Jamaian , Tom G. Mackay

Generalized ellipsometry, a non-destructive optical characterization technique, is employed to determine geometrical structure parameters and anisotropic dielectric properties of highly spatially coherent three-dimensionally nanostructured…

Optics · Physics 2015-06-16 Daniel Schmidt

We numerically investigated the plane-wave reflection-transmission characteristics of a columnar thin film (CTF) whose columns are made from a dissipative material but whose void regions are filled with an active material. By computing the…

Optics · Physics 2017-11-22 Tom G. Mackay , Akhlesh Lakhtakia

The homogenization of a composite material comprising three isotropic dielectric materials was investigated. The component materials were randomly distributed as spherical particles, with the particles of two of the component materials…

Optics · Physics 2016-06-29 Tom G. Mackay , Akhlesh Lakhtakia

We present the first report on fabrication of Hafnium aluminum nitride chiral sculptured thin films (CSTFs) using reactive magnetron sputtering in a glancing angle deposition configuration, and the analysis of its optical polarization…

Periodically patterned columnar thin films (PP-CTFs) were made by evaporating CaF2 and directing the vapor flux obliquely towards lithographically fabricated micrometer/sub-micrometer gratings. The growth of the PP-CTFs was controlled by…

Optics · Physics 2015-06-11 Jhuma Dutta , S. Anantha Ramakrishna , Akhlesh Lakhtakia

The Bruggeman formalism provides an estimate $\eps^{Br}_{hcm}$ of the relative permittivity of a homogenized composite material (HCM), arising from two component materials with relative permittivities $\eps_a$ and $\eps_b$. It can be…

Optics · Physics 2015-05-18 Siti S. Jamaian , Tom G. Mackay

Carbon nanofibers (CNF) are used as components of planar photonic crystals. Square and rectangular lattices and random patterns of vertically aligned CNF were fabricated and their properties studied using ellipsometry. We show that detailed…

The Bruggeman formalism for the homogenization of particulate composite materials is used to predict the effective permittivity dyadic of a two-constituent composite material with one constituent having the ability to display the Pockels…

Optics · Physics 2009-11-13 Akhlesh Lakhtakia , Tom G. Mackay

Implementations of the Bruggeman and Maxwell Garnett homogenization formalisms were developed to estimate the relative permittivity dyadic of a homogenized composite material (HCM), namely $\underline{\underline{\epsilon}}^{\rm HCM}$,…

Optics · Physics 2025-04-07 Héctor M. Iga-Buitrón , Tom G. Mackay , Akhlesh Lakhtakia

Two different formalisms for the homogenization of composite materials containing oriented ellipsoidal particles of isotropic dielectric materials are being named after Bruggeman. Numerical studies reveal clear differences between the two…

Optics · Physics 2015-06-03 Tom G. Mackay , Akhlesh Lakhtakia

Sculptured thin films (STFs) are nano-engineered materials whose columnar morphology is tailored to elicit desired optical responses upon excitation. Two canonical forms of STFs have been identified. Linear constitutive relations for…

Materials Science · Physics 2010-07-13 Akhlesh Lakhtakia

A slanted cobalt sculptured columnar thin film was fabricated using glancing angle deposition, and coated subsequently with graphene using a low temperature chemical vapor deposition process. The graphene deposition process preserves shape…

Materials Science · Physics 2015-12-22 P. M. Wilson , D. Schmidt , E. Schubert , M. Schubert , A. Sinitskii , T. Hofmann

The unit cell of a chevronic sculptured thin film (ChevSTF) comprises two identical columnar thin films (CTFs) except that the nanocolumns of the first are oriented at an angle \chi and nanocolumns of the second are oriented at an angle…

Optics · Physics 2017-11-22 Vikas Vepachedu , Patrick D. McAtee , Akhlesh Lakhtakia

We consider an anisotropic homogenized composite medium (HCM) arising from isotropic particulate component phases based on ellipsoidal geometries. For cubically nonlinear component phases, the corresponding zeroth-order…

Optics · Physics 2007-05-23 Tom G. Mackay

Morphology and performance are conjointed attributes of metamaterials, of which sculptured thin films (STFs) are examples. STFs are assemblies of nanowires that can be fabricated from many different materials, typically via physical vapor…

Optics · Physics 2014-07-01 Akhlesh Lakhtakia , Joseph B. Geddes

Being an assembly of identical upright helixes, a chiral sculptured thin film (CSTF) exhibits the circular Bragg phenomenon and can therefore be used as a circular- polarization filter in a spectral regime called the circular Bragg regime.…

Optics · Physics 2019-01-21 Vikas Vepachedu , Akhlesh Lakhtakia

This study elucidates the intriguing phenomenon of inverse thermal anisotropy in cadmium magnesium oxide (CdMgO) thin films, characterized by cross-plane thermal conductivity being greater than in-plane thermal conductivity, essential for…

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