Ultra-thin ultra-smooth and low-loss silver films on a germanium wetting layer

Chen, Weiqiang; Thoreson, Mark D.; Ishii, Satoshi; Kildishev, Alexander V.; Shalaev, Vladimir M.

doi:10.1364/oe.18.005124

Cited by 246 publications

(161 citation statements)

References 33 publications

Supporting

Mentioning

159

Contrasting

Unclassified

Order By: Relevance

“…Optical constants of individual silica and silver films were determined via ellipsometry using a JA Woollam VASE ellipsometer and the inferred optical constants showed good agreement with literature [32,33]. We modeled the dielectric permittivity function of silver as Ag ≈ F C + bound , with F C being the contribution from the free carriers and bound being the contribution of bound or valence electrons.…”

Section: Determining Optical Constantsmentioning

confidence: 65%

“…We modeled the dielectric permittivity function of silver as Ag ≈ F C + bound , with F C being the contribution from the free carriers and bound being the contribution of bound or valence electrons. Free electron motion in the silver is treated with a Drude dispersion while interband transition of bound electrons in the UV are modeled with five Lorentz osscillators as described by Chen et al [33,34]:…”

Section: Determining Optical Constantsmentioning

confidence: 99%

See 1 more Smart Citation

Ferrell–Berreman Modes in Plasmonic Epsilon-near-Zero Media

et al. 2014

View full text Add to dashboard Cite

We observe unique absorption resonances in silver/silica multilayer-based epsilon-near-zero (ENZ) metamaterials that are related to radiative bulk plasmon-polariton states of thin-films originally studied by Ferrell (1958) and Berreman (1963). In the local effective medium, metamaterial description, the unique effect of the excitation of these microscopic modes is counterintuitive and captured within the complex propagation constant, not the effective dielectric permittivities. Theoretical analysis of the band structure for our metamaterials shows the existence of multiple Ferrel-Berreman branches with slow light characteristics. The demonstration that the propagation constant reveals subtle microscopic resonances can lead to the design of devices where Ferrell-Berreman modes can be exploited for practical applications ranging from plasmonic sensing to imaging and absorption enhancement. Keywords: plasmon resonance, epsilon-near-zero, metamaterials, plasmonics An important class of artificial media are the epsilon-near-zero (ENZ) metamaterials that are designed to have a vanishing dielectric permittivity | | → 0. Waves propagating within ENZ media have a divergent phase velocity that can be used to guide light with zero phase advancement through sharp bends within sub-wavelength size channels [1, 2], or to tailor the phase of radiation/luminescence within a prescribed ENZ structure [3,4]. The electric field intensity within an ENZ medium can be enhanced relative to that in free space leading to strong light absorption [5]. This enhanced absorption in ENZ media has been exploited for novel polarization control and filtering in thin films [6], as well the proposal to use ENZ absorption resonances to tune thermal blackbody radiation of a heated object to the band-gap of a photovoltaic cell [7]. An enhanced non-linear response based upon strong spatial dispersion of waves in ENZ media has been demonstrated, and proposed for all-optical switching [8,9].Here we show theoretically and experimentally that ENZ metamaterials support unique absorption resonances related to radiative bulk plasmon-polaritons of thin metal films. These radiative bright modes exhibit properties in stark contrast to conventional dark modes of thin-film media (surface plasmon polaritons). The unique absorption resonances manifested in our metamaterials were originally studied by Ferrell in 1958 for plasmon-polaritonic thinfilms in the ultraviolet [10], and by Berreman in 1963 for phonon-polaritonic thin-films in the mid-infrared spectral region [11]. Surprisingly, two research communities have developed this independently with little communication or overlap until now: we therefore address these resonances as Ferrell-Berreman (FB) modes of our metamaterials. Counterintiutively, in the metamaterial effective medium picture, these resonances are not captured in the metamaterial dielectric permittivity constants but rather in the effective propagation constant. Furthermore, we show the existence of multiple branches of such FB modes that have slow ...

show abstract

Section: Determining Optical Constantsmentioning

confidence: 65%

Section: Determining Optical Constantsmentioning

confidence: 99%

Ferrell–Berreman Modes in Plasmonic Epsilon-near-Zero Media

et al. 2014

View full text Add to dashboard Cite

show abstract

“…This is due to the enhanced surface roughness of the Ag/Ge film, leading to lower optical loss. The achieved transmission was still lower than the theoretical level by the amount of ~15%, which may be attributed to the unwanted absorption incurred by the fabricated Ag mirror [17]. The center wavelength slightly shifted from 900 nm to ~845 nm, as the angle increased from 0 up to 50°.…”

Section: Device Fabrication and Experimental Resultsmentioning

confidence: 82%

“…6. The RMS roughness as measured decreased considerably from 8.4 to 0.54 nm, thereby relieving the optical scattering loss stemming from the uneven surface of the film [17].…”

Section: Device Fabrication and Experimental Resultsmentioning

confidence: 86%

Highly Angle-tolerant Spectral Filter Based on an Etalon Resonator Incorporating a High Index Cavity

Noh¹,

Yoon²,

Lee³

et al. 2012

Journal of the Optical Society of Korea

View full text Add to dashboard Cite

A high angular tolerance spectral filter was realized incorporating an etalon, which consists of a TiO2 cavity sandwiched between a pair of Ag/Ge mirrors. The effective angle was substantially extended thanks to the cavity's high refractive index. The device was created by embedding a 313-nm thick TiO2 film in 16-nm thick Ag/Ge films through sputtering, with the Ge layer alleviating the roughness and adhesion of the Ag layer. For normal incidence, the observed center wavelength and transmission were ~900 nm and ~60%, respectively; throughout the range of 50°, the relative wavelength shift and transmission variation amounted to only ~0.06 and ~4%, respectively.

show abstract

“…The loss arising in the device comes from the intrinsic loss of the metal [13,14] . Apparently, a thinner metal film leads to a lower loss, however, good-quality ultra-thin metal films are difficult to achieve and they have a relatively large imaginary part Im [ε m ] and the dielectric permittivity ε m will not remain constant as it becomes a function of layer thickness [14] . Furthermore, the hyperlens with alternating layers of metal and dielectric differ with the superlens, which only has a single metal layer.…”

mentioning

confidence: 99%

A hyperlens-based device for nanoscale focusing of light

Zhao¹,

Zheng²,

Li³

et al. 2012

中国光学快报

View full text Add to dashboard Cite

To resolve the problem of missed evanescent waves in a beam focusing system, a hyperlens-based beam focusing device is proposed in this letter. This device can convert the evanescent waves into propagating waves, and then a super-resolution spot is formed at the center of the hyperlens. The working principle of the device is presented, and the way in which the material and structural parameters of the hyperlens affect the resolution and transmission is analyzed in detail. A multibeam focusing device is optimally designed, and the simulated results verify that a nanoscale spot with a diameter of 15.6 nm (corresponding to λ0/24, where λ0 is the working wavelength in vacuum) is achieved, which is far less than the diffraction limited resolution with a value of 625 nm (1.7λ0). The device is expected to find numerous applications in optical data storage and nano-photolithography, among others.OCIS codes: 230.0230, 160.3918, 220.3630, 350.4238. doi: 10.3788/COL201210.042302. In an optical data storage and nano-lithography area, an ultra-small beam spot is required for information recording. With the phase transformation of an ideal positive lens, an input plane wave can be converted into a converging spherical wave and then eventually focused into a point at the focal plane. However, limited by diffraction, the ideal focusing point is through an Airy pattern. This can be explained by the fact that when the beam is focused toward the focal plane, the conservation of the angular momentum forces the tangential wave vector k θ to increase toward the center, however, light with k θ > k 0 corresponds to the evanescent wave that cannot reach the focal plane, where k 0 is the wavenumber in vacuum. According to the equation ∆x∆k ≈ 2π [1] , where ∆x is the beam size and ∆k is the bandwidth of the angular spectrum, the maximum ∆k that could be delivered is determined by the maximum transverse wavenumber k 0 ×NA(∆k = k 0 ×NA and NA is the numerical aperture of the focusing lens) and the minimum beam size ∆x is λ 0 /NA, which corresponds to the diffraction limit. To further reduce the beam size, we should find materials that allow waves with transverse wavenumber exceeding k 0 ×NA to propagate in it with a propagating wave mode, instead of an evanescent wave mode. Conventional isotropic materials such as optical glasses do not show such characteristics, whereas artificial materials such as metamaterials [2] hold such potential. By optimization design [3−5] , metamaterials can achieve the desired effective dielectric permittivity ε and magnetic permeability µ and have been theoretically shown to support propagating waves with very large wavenumbers. Lens fabricated by metamaterials, such as near-field planar superlens [6,7] , far-field superlens [8] , and hyperlens [9−12] , can support the propagation of evanescent waves and thus are capable of imaging an ultra-small object far below the diffraction limit. In this letter, we concentrate on another application and report on how a hyperlens-based device can work for super-resol...

show abstract

Ultra-thin ultra-smooth and low-loss silver films on a germanium wetting layer

Cited by 246 publications

References 33 publications

Ferrell–Berreman Modes in Plasmonic Epsilon-near-Zero Media

Ferrell–Berreman Modes in Plasmonic Epsilon-near-Zero Media

Highly Angle-tolerant Spectral Filter Based on an Etalon Resonator Incorporating a High Index Cavity

A hyperlens-based device for nanoscale focusing of light

Contact Info

Product

Resources

About