Richard Zhang

Richard Zhang
University of North Texas | UNT · Department of Mechanical and Energy Engineering

BS MIT, PhD Georgia Tech

About

10
Publications
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364
Citations

Publications

Publications (10)
Article
Metal-dielectric multilayers can be designed to exhibit remarkable optical properties, including negative refraction for subwavelength superlensing. In this study, the applicability of the medium-homogenized effective medium theory (EMT) in place of multilayered thin-film optics is examined. Three metal-dielectric material and thin film thickness c...
Article
Graphene-dielectric multilayers consisting of alternating layers of atom-thick graphene and nanometer-scale dielectric films exhibit characteristics of hyperbolic metamaterials, in which one positive and one negative permittivity are defined for orthogonal directions. Negative permittivity for electric field polarized in the direction parallel to t...
Article
During the past decade, research on carbon nanotubes has revealed potential advances in thermal engineering applications. The present study investigates the radiative absorption and reflection of vertically aligned carbon nanotubes (VACNTs) in the broad spectrum from the near-infrared to far-infrared regions. The optical constants of VACNT are mode...
Article
Full-text available
It has been shown that at small separation distances, thermal radiation between hyperbolic metamaterials is enhanced over blackbodies. This theoretical study considers near-field radiation when graphene is covered on the surfaces of two semi-infinite vertically aligned carbon nanotube (VACNT) arrays separated by a sub-micron vacuum gap. Doped graph...
Article
This study demonstrates the far-infrared self-collimation and low-loss transmission of aligned carbon nanotube (CNT) films or arrays. The anisotropic dielectric functions of the CNT array is modeled using the effective medium theory considering the degree of alignment. The spectral regions where hyperbolic dispersion is satisfied are in the far-inf...
Article
Excitation of surface plasmon polaritons helps to increase the near-field heat flux by orders of magnitude beyond the limit governed by Stefan-Boltzmann law. However, the photon tunneling probability is rather low, except for modes satisfying the resonance condition of surface plasmon polaritons. Broadband hyperbolic metamaterials can broaden the f...
Article
Full-text available
The near-field radiative heat transfer for two hyperbolic metamaterials, namely, graphite and vertically aligned carbon nanotubes (CNTs), is investigated. Graphite is a naturally existing uniaxial medium, while CNT arrays can be modeled as an effective anisotropic medium. Different hyperbolic modes can be separately supported by these materials in...

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