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Oscillatory penetration of near-fields in plasmonic excitation at metal-dielectric interfaces.

Lee SC, Kang JH, Park QH, Krishna S, Brueck SR - Sci Rep (2016)

Bottom Line: This unusual field penetration is explained by the interference between these contributions, and is experimentally confirmed through an aperture which is engineered with four arms stretched out from a simple circle to manipulate a specific plasmonic excitation available in the metal film.A numerical simulation quantitatively supports the experiment.This fundamental characteristic will impact plasmonics with the near-fields designed by aperture engineering for practical applications.

View Article: PubMed Central - PubMed

Affiliation: Center for High Technology Materials and Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, NM 87106, USA.

ABSTRACT
The electric field immediately below an illuminated metal-film that is perforated with a hole array on a dielectric consists of direct transmission and scattering of the incident light through the holes and evanescent near-field from plasmonic excitations. Depending on the size and shape of the hole apertures, it exhibits an oscillatory decay in the propagation direction. This unusual field penetration is explained by the interference between these contributions, and is experimentally confirmed through an aperture which is engineered with four arms stretched out from a simple circle to manipulate a specific plasmonic excitation available in the metal film. A numerical simulation quantitatively supports the experiment. This fundamental characteristic will impact plasmonics with the near-fields designed by aperture engineering for practical applications.

No MeSH data available.


Related in: MedlinePlus

Experiment demonstrating NFI with aperture engineering.(a) An example of a Celtic cross (CX) aperture designed for the suppression of the SR2- while retaining the SR1-resonance. (b) A SEM image of a hole fabricated in this work that mimics (a). Plots of experimental responsivity vs. wavelength of (c) the reference device and (d) the CX device. Negative bias means grounding the top contact in Fig. 1a. In (c), the black line on the curve for bias of −3.4 V was used in the simulation to scale κA. In (d), a brown arrow indicates a shoulder at ~9.7 μm. The color code in (c) is identically applied to (d). Inset in (d) A SEM image of the 2D array in the MPC with the CX aperture in (b) that was integrated atop the QDIP semiconductor structure.
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f3: Experiment demonstrating NFI with aperture engineering.(a) An example of a Celtic cross (CX) aperture designed for the suppression of the SR2- while retaining the SR1-resonance. (b) A SEM image of a hole fabricated in this work that mimics (a). Plots of experimental responsivity vs. wavelength of (c) the reference device and (d) the CX device. Negative bias means grounding the top contact in Fig. 1a. In (c), the black line on the curve for bias of −3.4 V was used in the simulation to scale κA. In (d), a brown arrow indicates a shoulder at ~9.7 μm. The color code in (c) is identically applied to (d). Inset in (d) A SEM image of the 2D array in the MPC with the CX aperture in (b) that was integrated atop the QDIP semiconductor structure.

Mentions: In Fig. 1, the incident light is resonantly coupled to an SPW if its wavelength satisfies (1) for the plasmonic excitation at the MPC/QDIP interface that result in evanescent near-fields interacting with the absorber underneath the MPC and therefore directly revealing NFI from the variation of the photoresponse of the detector. In Fig. 2, Ez,MPC varies with d and SR orders. Such strength variation can be examined experimentally with the QDIP in Fig. 1 which has two-color response near λSR1 and λSR2. Based on the variation in Fig. 2, retaining an enhanced SR1 at λSR1 while suppressing the response at SR2 at λSR2 by NFI is available with a single MPC by aperture engineering. Figure 3a shows a basic aperture shape designed for this purpose, a circular hole with four arms stretched out along the pattern symmetry directions. This is similar to the union of a circle and a cross, referred to as a Celtic cross (CX). Figure 3b is a scanning electron microscope (SEM) image of the aperture fabricated for this work that mimics Fig. 3a. It has four ~1 μm-wide arms and a diagonal opening ~1.8 μm, longer than p/2. Its largest opening gap is ~2.4 μm as indicated. Its shape and overall pattern have four-fold symmetry, so the response is independent of the polarization of the incident light. It retains the strength of SR1 at the longest wavelength with the arms but allows direct transmission/scattering through individual apertures for SR2 and higher-order SRs with the extended aperture provided by these arms. As a result of lithographic limitations, most of the right-angle corners of Fig. 3a were not replicated in Fig. 3b but the overall shape retains the characteristics expected from the hole in Fig. 3a, as confirmed experimentally.


Oscillatory penetration of near-fields in plasmonic excitation at metal-dielectric interfaces.

Lee SC, Kang JH, Park QH, Krishna S, Brueck SR - Sci Rep (2016)

Experiment demonstrating NFI with aperture engineering.(a) An example of a Celtic cross (CX) aperture designed for the suppression of the SR2- while retaining the SR1-resonance. (b) A SEM image of a hole fabricated in this work that mimics (a). Plots of experimental responsivity vs. wavelength of (c) the reference device and (d) the CX device. Negative bias means grounding the top contact in Fig. 1a. In (c), the black line on the curve for bias of −3.4 V was used in the simulation to scale κA. In (d), a brown arrow indicates a shoulder at ~9.7 μm. The color code in (c) is identically applied to (d). Inset in (d) A SEM image of the 2D array in the MPC with the CX aperture in (b) that was integrated atop the QDIP semiconductor structure.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835736&req=5

f3: Experiment demonstrating NFI with aperture engineering.(a) An example of a Celtic cross (CX) aperture designed for the suppression of the SR2- while retaining the SR1-resonance. (b) A SEM image of a hole fabricated in this work that mimics (a). Plots of experimental responsivity vs. wavelength of (c) the reference device and (d) the CX device. Negative bias means grounding the top contact in Fig. 1a. In (c), the black line on the curve for bias of −3.4 V was used in the simulation to scale κA. In (d), a brown arrow indicates a shoulder at ~9.7 μm. The color code in (c) is identically applied to (d). Inset in (d) A SEM image of the 2D array in the MPC with the CX aperture in (b) that was integrated atop the QDIP semiconductor structure.
Mentions: In Fig. 1, the incident light is resonantly coupled to an SPW if its wavelength satisfies (1) for the plasmonic excitation at the MPC/QDIP interface that result in evanescent near-fields interacting with the absorber underneath the MPC and therefore directly revealing NFI from the variation of the photoresponse of the detector. In Fig. 2, Ez,MPC varies with d and SR orders. Such strength variation can be examined experimentally with the QDIP in Fig. 1 which has two-color response near λSR1 and λSR2. Based on the variation in Fig. 2, retaining an enhanced SR1 at λSR1 while suppressing the response at SR2 at λSR2 by NFI is available with a single MPC by aperture engineering. Figure 3a shows a basic aperture shape designed for this purpose, a circular hole with four arms stretched out along the pattern symmetry directions. This is similar to the union of a circle and a cross, referred to as a Celtic cross (CX). Figure 3b is a scanning electron microscope (SEM) image of the aperture fabricated for this work that mimics Fig. 3a. It has four ~1 μm-wide arms and a diagonal opening ~1.8 μm, longer than p/2. Its largest opening gap is ~2.4 μm as indicated. Its shape and overall pattern have four-fold symmetry, so the response is independent of the polarization of the incident light. It retains the strength of SR1 at the longest wavelength with the arms but allows direct transmission/scattering through individual apertures for SR2 and higher-order SRs with the extended aperture provided by these arms. As a result of lithographic limitations, most of the right-angle corners of Fig. 3a were not replicated in Fig. 3b but the overall shape retains the characteristics expected from the hole in Fig. 3a, as confirmed experimentally.

Bottom Line: This unusual field penetration is explained by the interference between these contributions, and is experimentally confirmed through an aperture which is engineered with four arms stretched out from a simple circle to manipulate a specific plasmonic excitation available in the metal film.A numerical simulation quantitatively supports the experiment.This fundamental characteristic will impact plasmonics with the near-fields designed by aperture engineering for practical applications.

View Article: PubMed Central - PubMed

Affiliation: Center for High Technology Materials and Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, NM 87106, USA.

ABSTRACT
The electric field immediately below an illuminated metal-film that is perforated with a hole array on a dielectric consists of direct transmission and scattering of the incident light through the holes and evanescent near-field from plasmonic excitations. Depending on the size and shape of the hole apertures, it exhibits an oscillatory decay in the propagation direction. This unusual field penetration is explained by the interference between these contributions, and is experimentally confirmed through an aperture which is engineered with four arms stretched out from a simple circle to manipulate a specific plasmonic excitation available in the metal film. A numerical simulation quantitatively supports the experiment. This fundamental characteristic will impact plasmonics with the near-fields designed by aperture engineering for practical applications.

No MeSH data available.


Related in: MedlinePlus