Silver/silicon dioxide/silver sandwich films in the blue-to-red spectral regime with negative-real refractive index

Jen, Yi Jun; Lakhtakia, Akhlesh; Yu, Ching Wei; Jhou, Jheng Jie; Wang, Wei-Hao; Lin, Mingli; Wu, Haijun; Liao, Hung

doi:10.1063/1.3658624

Cited by 13 publications

(8 citation statements)

References 19 publications

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“…Specifically, in the visible range, negative refraction has been demonstrated using metallic nanowires embedded in a dielectric matrix 3,4 , fishnet structures [5][6][7] , metaldielectric stacks/sandwiches [8][9][10] , planar waveguides 11 and metal-insulator-metal coaxial waveguides 12,13 . Despite the tremendous progress in the design and fabrication of NIM, developing high performance NIM without active loss compensation in the optical domain remains a challenge.…”

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confidence: 99%

Semiconductor-Metal-Semiconductor Core-Multishell Nanowires as Negative-Index Metamaterial in Visible Domain

Ramadurgam

Yang

2014

Sci Rep

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Negative-index metamaterials (NIMs) exhibiting both negative refraction as well as phase reversal, particularly in the visible range, have drawn considerable attention in the past decade due to their potential applications in cloaking, sensing and sub-diffraction-limit imaging. NIM are often realized by arraying sub-wavelength nanostructures (meta-atoms) exhibiting spectrally overlapped magnetic and electric resonances. Most designs so far use scaling down of the resonant elements and employ materials with the right optical constants to obtain NIM in the visible range. However, large losses due to absorption in most metals and semiconductors as well as reduced coupling with light due to scaling pose a challenge to achieving low-loss NIM. Here, we employ plasmon hybridization in semiconductor-metal-semiconductor core-multishell (CMS) nanowires as a unique approach to design low loss, isotropic and polarization dependant NIM in the visible range. Based on numerical simulations, we demonstrate an effective refractive index of 21 and a figure of merit (FOM) of 17 at 650 nm for a representative Si-Ag-Si CMS nanowire NIM and a refractive index of 21, FOM of 25 at 590 nm for a GaP-Ag-GaP CMS nanowire NIM.I n the past decade many breakthroughs have been made towards realizing isotropic, bulk negative-index metamaterial (NIM) in various spectral regimes 1,2 . Specifically, in the visible range, negative refraction has been demonstrated using metallic nanowires embedded in a dielectric matrix 3,4 , fishnet structures 5-7 , metaldielectric stacks/sandwiches 8-10 , planar waveguides 11 and metal-insulator-metal coaxial waveguides 12,13 . Despite the tremendous progress in the design and fabrication of NIM, developing high performance NIM without active loss compensation in the optical domain remains a challenge. This is due to large losses arising from both the NIM designs as well as the materials. The best experimental value for the figure of merit FOM~R e n eff À Á Im n eff À Á reported so far are 3.34 in the visible and 3.5 in near-infrared range obtained from fishnet NIM 7,14 . More recently, theoretical designs have been reported for low loss plasmonic NIM utilizing the geometry dependant Mie excitations in Ag-GaP hybrid rods 15 , Ag-Si core-shell (CS) nanospheres 16 and nanowires 17 . Specifically, in the CS structures the core diameter and the shell thickness are chosen so that the magnetic dipole resonance arising from the dielectric shell and the electric dipole resonance (localized surface plasmon resonance -LSPR) in the metal core spectrally overlap. Around this double resonance, both the electric and magnetic dipole moments in the nanosphere/wire are strongly negative. These sub-wavelength CS structures demonstrating such double resonance feature satisfy the requirements of a NIM meta-atom, therefore CS structures can be engineered into a NIM with simultaneously negative permittivity and permeability. Since the natural magnetic resonance occurring in the dielectric shell is coupled to the LSPR within the same CS...

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confidence: 99%

Semiconductor-Metal-Semiconductor Core-Multishell Nanowires as Negative-Index Metamaterial in Visible Domain

Ramadurgam

Yang

2014

Sci Rep

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“…We use the qualifier equivalent to denote the constitution of a homogeneous film with the same reflection and transmission coefficients for normal incidence as that of the SWF under examination1516. Despite the non-uniqueness inherent in their determination (even though we ensured the satisfaction of certain reasonable constraints12), these equivalent parameters help understand and explain the reflection and transmission characteristics for normal-incidence conditions.…”

Section: Resultsmentioning

confidence: 99%

“…Recently, we reported101112 the fabrication of a silver (Ag)-silicon dioxide (SiO 2 )- silver (Ag) sandwich film (SWF) comprising upright nanopillars by the oblique-angle-deposition (OAD) technique1314. For normal incidence in the blue-to-red spectral regime, the SWF was found to display an equivalent refractive index with a negative real part.…”

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confidence: 99%

Metal/dielectric/metal sandwich film for broadband reflection reduction

Jen

Lakhtakia

Lin

et al. 2013

Sci Rep

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A film comprising randomly distributed metal/dielectric/metal sandwich nanopillars with a distribution of cross-sectional diameters, displayed extremely low reflectance over the blue-to-red regime, when coated on glass and illuminated normally. When it is illuminated by normally incident light, this sandwich film (SWF) has a low extinction coefficient, its phase thickness is close to a negative wavelength in the blue-to-red spectral regime, and it provides weakly dispersive forward and backward impedances, so that reflected waves from the two faces of the SWF interfere destructively. Broadband reflection-reduction, over a wide range of incidence angles and regardless of the polarization state of the incident light, was observed when the SWF was deposited on polished silicon.

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“…The correct solution should satisfy the 3 criteria: (1) The real part of the equivalent admittance should be positive; (2) the imaginary part of the equivalent refractive index should be negative; (3) both N eq = n eq − ik eq and E eq = E r + iE i as functions of wavelength or any constitutive parameter should be continuous [19]. It is particular that a specific branch was unable to satisfy the criteria over the whole wavelengths.…”

Section: Methodsmentioning

confidence: 99%

Design a Stratiform Metamaterial with Precise Optical Property

Jen

Liu

2019

Symmetry

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In this work, a stratiform metamaterial is arranged as multiple periods of metal-dielectric symmetrical film stack to provide precise equivalent refractive index and admittance. There are multiple solutions of equivalent refractive index retrieved from the characteristic matrix of the film stack. The correct refractive index is derived by connecting different branches of solution at different ranges of wavelength or thickness of the dielectric layer. The refractive index of an Ag-TiO 2 five-layered symmetrical film stack shown in previous work is demonstrated to be positive real instead of negative real. The associated type I iso-frequency curve supports negative refraction. In order to extend the operating wavelength of type I metamaterial, the number of the metal-dielectric symmetrical film stack is increased to reduce the thickness of the dielectric film to approach subwavelength requirement.

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Silver/silicon dioxide/silver sandwich films in the blue-to-red spectral regime with negative-real refractive index

Cited by 13 publications

References 19 publications

Semiconductor-Metal-Semiconductor Core-Multishell Nanowires as Negative-Index Metamaterial in Visible Domain

Semiconductor-Metal-Semiconductor Core-Multishell Nanowires as Negative-Index Metamaterial in Visible Domain

Metal/dielectric/metal sandwich film for broadband reflection reduction

Design a Stratiform Metamaterial with Precise Optical Property

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