Model
light-confining Tamm plasmon cavities based on gold-coated
nanoporous anodic alumina photonic crystals (TMM–NAA–PCs)
with spectrally tunable resonance bands were engineered. Laplacian
and Lorentzian NAA–PCs produced by a modified Gaussian-like
pulse anodization approach showed well-resolved, high-quality photonic
stopbands, the position of which was precisely controlled across the
visible spectrum by the periodicity in the input anodization profile.
These PC structures were used as a platform material to develop highly
reflective distributed Bragg mirrors, the top sides of which were
coated with a thin gold film. The resulting nanoporous hybrid plasmonic–photonic
crystals showed strong light-confining properties attributed to Tamm
plasmon resonances at three specific positions of the visible spectrum.
These structures achieved high sensitivity to changes in refractive
index, with a sensitivity of ∼106 nm RIU–1. The optical sensitivity of TMM–NAA–PCs was assessed
in real time, using a model chemically selective binding interaction
between thiol-containing molecules and gold. The optical sensitivity
was found to rely linearly on the spectral position of the Tamm resonance
band, for both Laplacian and Lorentzian TMM–NAA–PCs.
The density of self-assembled monolayers of thiol-containing analyte
molecules formed on the surface of the metallic film directly contributes
to the dependence of sensitivity on TMM resonance position in these
optical transducers. Our findings provide opportunities to integrate
TMM modes in NAA-based photonic crystal structures, with promising
potential for optical technologies and applications requiring high-quality
surface plasmon resonance bands.
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