White Light Generation and Anisotropic Damage in Gold Films near Percolation Threshold

Novikov, Sergey M.; Frydendahl, Christian; Beermann, Jonas; Zenin, Vladimir A.; Stenger, Nicolas; Coello, Víctor; Mortensen, N. Asger; Bozhevolnyi, Sergey I.

doi:10.1021/acsphotonics.7b00107

Cited by 31 publications

(34 citation statements)

References 61 publications

(210 reference statements)

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“…As previously shown by near-field and two-photon luminescence microscopy [22,25], the strongest FE is generated near the percolation threshold. The presence of such strong FE has recently allowed the realization of the color printing and laser-induced modification of local resonance properties in near-percolation metal films [34][35][36].…”

supporting

confidence: 68%

“…One of the easiest and cheapest methods for the fabrication of large-area SERS substrates relies on the usage of semi-continuous metal films near the percolation threshold [20][21][22], the critical point at which individual metal clusters start forming connected structures across the substrate domains [20,23,24]. The concentration of such hot spots (along with the average value of the SERS signal gain) is expected to be maximal near the percolation threshold [22,25]. These films are usually prepared by the high-vacuum evaporation of a noble metal (gold, silver, or copper) onto a supporting substrate (semiconductor or dielectric).…”

mentioning

confidence: 99%

“…Graphene was chosen as a basis for one type of substrate due to its unique physical properties [30,31]. The interest in graphene is mainly due to its biocompatibility and ability to quench photoluminescence [32,33].As previously shown by near-field and two-photon luminescence microscopy [22,25], the strongest FE is generated near the percolation threshold. The presence of such strong FE has recently allowed the realization of the color printing and laser-induced modification of local resonance properties in near-percolation metal films [34][35][36].…”

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confidence: 99%

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Surface-Enhanced Raman Spectroscopy on Hybrid Graphene/Gold Substrates near the Percolation Threshold

et al. 2020

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Graphene is a promising platform for surface-enhanced Raman spectroscopy (SERS)-active substrates, primarily due to the possibility of quenching photoluminescence and fluorescence. Here we study ultrathin gold films near the percolation threshold fabricated by electron-beam deposition on monolayer CVD graphene. The advantages of such hybrid graphene/gold substrates for surface-enhanced Raman spectroscopy are discussed in comparison with conventional substrates without the graphene layer. The percolation threshold is determined by independent measurements of the sheet resistance and effective dielectric constant by spectroscopic ellipsometry. The surface morphology of the ultrathin gold films is analyzed by the use of scanning electron microscopy (SEM) and atomic force microscopy (AFM), and the thicknesses of the films in addition to the quartz-crystal mass-thickness sensor are also measured by AFM. We experimentally demonstrate that the maximum SERS signal is observed near and slightly below the percolation threshold. In this case, the region of maximum enhancement of the SERS signal can be determined using the figure of merit (FOM), which is the ratio of the real and imaginary parts of the effective dielectric permittivity of the films. SERS measurements on hybrid graphene/gold substrates with the dye Crystal Violet show an enhancement factor of ~105 and also demonstrate the ability of graphene to quench photoluminescence by an average of ~60%.

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confidence: 68%

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confidence: 99%

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Surface-Enhanced Raman Spectroscopy on Hybrid Graphene/Gold Substrates near the Percolation Threshold

et al. 2020

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“…[13,14] Therefore, it is not surprising that they raised interest in mechanics, [15] hydrodynamics, [16] electronics, [17] and photonics. [18] Much effort, mostly theoretical, has been devoted to accurately determine ρ c in arbitrary dimensions. [19] However, accurate experimental nanoscale realizations of particulate systems close to the percolation threshold are scarce.…”

Section: Doi: 101002/smll202002735mentioning

confidence: 99%

Vacancies in Self‐Assembled Crystals: An Archetype for Clusters Statistics at the Nanoscale

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Pecharromán

et al. 2020

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“…30 Interestingly, white-light generation has been found to be the most ecient in such lms. Theoretical models suggest that the nonlocal response dampen the local transverse electromagnetic eld and facilitates excitation of the longitudinal modes.…”

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Evidence of High-Order Nonlinearities in Supercontinuum White-Light Generation from a Gold Nanofilm

et al. 2018

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White-light supercontinuum generation can be readily observed when gold nanostructures are irradiated with short pulses of light. It is believed that the nanostructures enhance the optical elds, which facilitates the supercontinuum white-light generation from the surrounding environment or the substrate. Here, we investigate the dierent nonlinear processes that contribute to the generation of the supercontinuum from plasmonic nanostructures themselves using a technique that isolates the dierent nonlinear contributions. By exciting a gold nanolm with a pair of frequency shifted optical frequency combs, we demonstrate multiple modulation frequencies in the supercontinuum. and supercontinuum (SC) generation 5,10 can be observed at higher intensities. SC generation is also routinely observed when intense pulsed lasers are focused onto any dielectric medium, 11 and it has been suggested that the SC from the gold nanostructures originates due to the emission from the surrounding dielectric medium. The spectral broadening leading to the SC generated from the dielectrics is mainly due to the third-order nonlinear processes such as self-phase modulation (SPM), cross-phase modulation (XPM) and four-wave mixing (FWM). In such a process, the spectral width of the broaden spectrum, ∆ω, is proportional to the product of the intensity and the interaction length, ∆ω ∝ Iz (here I is the intensity and z is the interaction length). 11 In a typical dielectric medium, an excitation intensity of 10 13 10 14 W/cm 2 and the interaction length of few millimeters are necessary to observe appreciable spectral broadening. Alternatively, one can substantially increase the interaction length by using guided propagation of pulses in nonlinear optical (NLO) bers in order to generate broad spectrum at lower excitation intensity. 1214 The SC from gold nanostructures, on the other hand, is observed at a relatively lower excitation intensity (∼ 10 10 − 10 11 W/cm 2 ) as well as very short interaction length (∼ few tens of nanometers). 10 Although gold 2 nanostructures can locally enhance the electric eld, the intensity that is required to generate the SC within the interaction length of few nanometers from the surrounding substrate by SPM, XPM and FWM is about 10 18 W/cm 2 . As metal nanostructures cannot withstand such high intensities, it is unlikely that SC from the gold nanostructures and the dielectric medium originate from the same nonlinear processes.The SC generation has not been observed from the bulk gold despite its high intrinsic nonlinearity. 15 Thus it is reasonable that the optical properties of gold that only manifest in the nanostructures contribute to the nonlinear process. The nonlocal response of free electrons to the incident light elds in metals is one of such properties. 16 Generally, lightmatter interactions in dielectric materials are described by the local-response approximation (LRA) in which the electric displacement eld D(r, ω) induced at a point r by an incident light eld of frequency ω is proportional to the...

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White Light Generation and Anisotropic Damage in Gold Films near Percolation Threshold

Cited by 31 publications

References 61 publications

Surface-Enhanced Raman Spectroscopy on Hybrid Graphene/Gold Substrates near the Percolation Threshold

Surface-Enhanced Raman Spectroscopy on Hybrid Graphene/Gold Substrates near the Percolation Threshold

Vacancies in Self‐Assembled Crystals: An Archetype for Clusters Statistics at the Nanoscale

Evidence of High-Order Nonlinearities in Supercontinuum White-Light Generation from a Gold Nanofilm

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