Tailoring Optical and Plasmon Resonances in Core-shell and Core-multishell Nanowires for Visible Range Negative Refraction and Plasmonic Light Harvesting: A Review

Abstract

Semiconductor nanowires (NWs) are sub-wavelength structures which exhibit strong optical (Mie) resonances in the visible range. In addition to such optical resonances, the localized surface plasmon resonances (LSPRs) in metal-semiconductor core-shell (CS) and core-multishell (CMS) NWs can be tailored to achieve novel negative-index metamaterials (NIM), extreme absorbers, invisibility cloaks and sensors. Particularly, in this review, we focus on our recent theoretical studies which highlight the versatility of CS and CMS NWs for: 1) the design of negative-index metamaterials in the visible range and 2) plasmonic light harvesting in ultrathin photocatalyst layers for water splitting. Utilizing the LSPR in the metal layer and the magnetic dipole (Mie) resonance in the semiconductor shell under transverse electric (TE) polarization, semiconductor-metal-semiconductor CMS NWs can be designed to exhibit spectrally overlapping electric and magnetic resonances in the visible range. NWs exhibiting such double resonances can be considered as meta-atoms and arrayed to form polarization dependent, low-loss NIM. Alternatively, by tuning the LSPR in the TE polarization and the optical resonance in the transverse magnetic (TM) polarization of metal-photocatalyst CS and semiconductor-metal-photocatalyst CMS NWs, the absorption within ultrathin (sub-50 nm) photocatalyst layers can be substantially enhanced. Notably, aluminum and copper based NWs provide absorption enhancement remarkably close to silver and gold based NWs, respectively. Further, such absorption is polarization independent and remains high over a large range of incidence angles and permittivity of the medium. Therefore, due to the tunability of their optical properties, CS and CMS NWs are expected to be vital components for the design of nanophotonic devices.

Core–Shell Structures Prepared by Atomic Layer Deposition on GaAs Nanowires

“…A large area of coreshell applications are related to photodiodes and photovoltaics, demonstrating significant advantages over planar structures and other device configurations in terms of radial charge collection and cost reduction, reduced reflection of injected light, and improving efficiency based on positional carrier separation [1][2][3][4][5]. Nanophotonics [6][7][8][9][10], non-linear optics and plasmonics [11,12], thermoelectrics [13], recognition of biomolecules, and biosensing [14] are among important applications of semiconductor quasi-one-dimensional core-shell structures. Among many arrays of core-shell nanowires, those with ZnO and TiO 2 shells are widely explored for various applications [5,6,15,16].…”

Design of a magnetically driven current cloak

“…The term metamaterial is commonly used to describe a material engineered in such way [7]. Over the following years, several types of cloaks were reported in the optical [8][9][10][11][12][13] and microwave [14][15][16][17][18] frequency ranges.…”

Design of an Externally Driven Current Cloak

“…Pendry and Leohardt coined the term metamaterial to describe a material engineered in such way. Over the following years, several types of cloaks were reported in the optical [9][10][11][12][13] and microwave [14][15][16][17][18] frequency ranges.…”