Limits...
Absorption-induced scattering and surface plasmon out-coupling from absorber-coated plasmonic metasurfaces.

Petoukhoff CE, O'Carroll DM - Nat Commun (2015)

Bottom Line: Here we identify three distinct mode types of absorber-coated plasmonic metasurfaces: localized and propagating surface plasmons and a previously unidentified optical mode type called absorption-induced scattering.Furthermore, we show that surface plasmons are backscattered when the crystallinity of the absorber is low but are absorbed for more crystalline absorber coatings.This work furthers our understanding of light-matter interactions between absorbers and surface plasmons to enable practical optoelectronic applications of metasurfaces.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, Rutgers University, 607 Taylor Road, Piscataway, New Jersey 08854, USA.

ABSTRACT
Interactions between absorbers and plasmonic metasurfaces can give rise to unique optical properties not present for either of the individual materials and can influence the performance of a host of optical sensing and thin-film optoelectronic applications. Here we identify three distinct mode types of absorber-coated plasmonic metasurfaces: localized and propagating surface plasmons and a previously unidentified optical mode type called absorption-induced scattering. The extinction of the latter mode type can be tuned by controlling the morphology of the absorber coating and the spectral overlap of the absorber with the plasmonic modes. Furthermore, we show that surface plasmons are backscattered when the crystallinity of the absorber is low but are absorbed for more crystalline absorber coatings. This work furthers our understanding of light-matter interactions between absorbers and surface plasmons to enable practical optoelectronic applications of metasurfaces.

No MeSH data available.


Mie-absorption-induced scattering in absorber-coated planar Ag films.(a) DF scattered-light spectra of various neat conjugated polymer (n, solid lines) and polymer:fullerene blend (b, dashed lines) coatings on planar Ag substrates. Insets are true-colour DF images of the coatings on planar Ag substrates and were captured from regions where the DF spectra were acquired. All images are on the same length scale (scale bar, 100 μm, and is shown for PTB7:PC70BM/Ag). (b) AFM surface topography of planar Ag substrates with neat polymer and polymer:fullerene blend coatings corresponding to those in (a). Root-mean-square (r.m.s.) surface roughness values are shown on each image; all images are on the same length scale (scale bar, 500 nm, and is shown for neat PTB7) and height intensity scale, except for neat P3HT (height intensity values are 2.5 × the values on the height scale bar).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4557133&req=5

f2: Mie-absorption-induced scattering in absorber-coated planar Ag films.(a) DF scattered-light spectra of various neat conjugated polymer (n, solid lines) and polymer:fullerene blend (b, dashed lines) coatings on planar Ag substrates. Insets are true-colour DF images of the coatings on planar Ag substrates and were captured from regions where the DF spectra were acquired. All images are on the same length scale (scale bar, 100 μm, and is shown for PTB7:PC70BM/Ag). (b) AFM surface topography of planar Ag substrates with neat polymer and polymer:fullerene blend coatings corresponding to those in (a). Root-mean-square (r.m.s.) surface roughness values are shown on each image; all images are on the same length scale (scale bar, 500 nm, and is shown for neat PTB7) and height intensity scale, except for neat P3HT (height intensity values are 2.5 × the values on the height scale bar).

Mentions: To investigate whether this new scattering peak occurred ubiquitously for absorber coatings, we conducted DF scattered-light spectroscopy on planar Ag films with various organic semiconductor coatings (Fig. 2a). The scattering spectra showed peaks occurring at wavelengths red shifted from the absorption edge for only certain coatings, particularly those coatings with large lateral feature sizes (∼100 to 350 nm) or high surface roughness (greater than ∼1 nm r.m.s; Fig. 2). We attributed the scattering peak observed for coatings with more irregular surfaces to Mie scattering by nanoscale surface features in the organic material modified by its absorption (that is, Mie-‘absorption-induced scattering,' or Mie-AIS), which we have reproduced through simulations (Supplementary Fig. 6). Additional coated planar Ag films which did not exhibit this Mie-AIS peak (because the coatings had very planar surfaces) are shown in Supplementary Fig. 7.


Absorption-induced scattering and surface plasmon out-coupling from absorber-coated plasmonic metasurfaces.

Petoukhoff CE, O'Carroll DM - Nat Commun (2015)

Mie-absorption-induced scattering in absorber-coated planar Ag films.(a) DF scattered-light spectra of various neat conjugated polymer (n, solid lines) and polymer:fullerene blend (b, dashed lines) coatings on planar Ag substrates. Insets are true-colour DF images of the coatings on planar Ag substrates and were captured from regions where the DF spectra were acquired. All images are on the same length scale (scale bar, 100 μm, and is shown for PTB7:PC70BM/Ag). (b) AFM surface topography of planar Ag substrates with neat polymer and polymer:fullerene blend coatings corresponding to those in (a). Root-mean-square (r.m.s.) surface roughness values are shown on each image; all images are on the same length scale (scale bar, 500 nm, and is shown for neat PTB7) and height intensity scale, except for neat P3HT (height intensity values are 2.5 × the values on the height scale bar).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4557133&req=5

f2: Mie-absorption-induced scattering in absorber-coated planar Ag films.(a) DF scattered-light spectra of various neat conjugated polymer (n, solid lines) and polymer:fullerene blend (b, dashed lines) coatings on planar Ag substrates. Insets are true-colour DF images of the coatings on planar Ag substrates and were captured from regions where the DF spectra were acquired. All images are on the same length scale (scale bar, 100 μm, and is shown for PTB7:PC70BM/Ag). (b) AFM surface topography of planar Ag substrates with neat polymer and polymer:fullerene blend coatings corresponding to those in (a). Root-mean-square (r.m.s.) surface roughness values are shown on each image; all images are on the same length scale (scale bar, 500 nm, and is shown for neat PTB7) and height intensity scale, except for neat P3HT (height intensity values are 2.5 × the values on the height scale bar).
Mentions: To investigate whether this new scattering peak occurred ubiquitously for absorber coatings, we conducted DF scattered-light spectroscopy on planar Ag films with various organic semiconductor coatings (Fig. 2a). The scattering spectra showed peaks occurring at wavelengths red shifted from the absorption edge for only certain coatings, particularly those coatings with large lateral feature sizes (∼100 to 350 nm) or high surface roughness (greater than ∼1 nm r.m.s; Fig. 2). We attributed the scattering peak observed for coatings with more irregular surfaces to Mie scattering by nanoscale surface features in the organic material modified by its absorption (that is, Mie-‘absorption-induced scattering,' or Mie-AIS), which we have reproduced through simulations (Supplementary Fig. 6). Additional coated planar Ag films which did not exhibit this Mie-AIS peak (because the coatings had very planar surfaces) are shown in Supplementary Fig. 7.

Bottom Line: Here we identify three distinct mode types of absorber-coated plasmonic metasurfaces: localized and propagating surface plasmons and a previously unidentified optical mode type called absorption-induced scattering.Furthermore, we show that surface plasmons are backscattered when the crystallinity of the absorber is low but are absorbed for more crystalline absorber coatings.This work furthers our understanding of light-matter interactions between absorbers and surface plasmons to enable practical optoelectronic applications of metasurfaces.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, Rutgers University, 607 Taylor Road, Piscataway, New Jersey 08854, USA.

ABSTRACT
Interactions between absorbers and plasmonic metasurfaces can give rise to unique optical properties not present for either of the individual materials and can influence the performance of a host of optical sensing and thin-film optoelectronic applications. Here we identify three distinct mode types of absorber-coated plasmonic metasurfaces: localized and propagating surface plasmons and a previously unidentified optical mode type called absorption-induced scattering. The extinction of the latter mode type can be tuned by controlling the morphology of the absorber coating and the spectral overlap of the absorber with the plasmonic modes. Furthermore, we show that surface plasmons are backscattered when the crystallinity of the absorber is low but are absorbed for more crystalline absorber coatings. This work furthers our understanding of light-matter interactions between absorbers and surface plasmons to enable practical optoelectronic applications of metasurfaces.

No MeSH data available.