370
L. D. Negro et al.
approximately a factor of 3 is measured for the GA spiral at 950 nm. The increase in
photocurrent results from the interplay of plasmonic-photonic effects in GA spirals,
which contribute to the overall enhancement as follows: by providing better coupling
of incident radiation into the thin Si layer due to photonic wide-angle scattering; by
enhancing the intensity of the nanoparticle near-fields at the Si interface owing to
better LSP coupling in the plane of the array compared to periodic structures. A
detailed comparison with optimized periodic grating structures in discussed in Ref.
[67].
We observe finally that the experimentally measured 31 % integrated enhancement
for GA spiral arrays has been demonstrated with only 25 % of the active photodetector
device area covered by GA arrays (Fig 9.21d, inset). These results highlight the
potential for even greater enhancement for complete device area coverage using
GA spirals. Moreover, in the context of thin-films absorption enhancement, a large
class of deterministic aperiodic spiral arrays with divergence angles different from
the golden angle remains to be explored, promising additional flexibility due to the
presence of multiple scattering rings in Fourier space [65].
9.4 Outlook and Conclusions
While light transport and localization phenomena in periodic and random structures
have been investigated for decades, the study of deterministic aperiodic structures is
still in its infancy. Deterministic aperiodic optical structures defines a novel, fascinating, and highly interdisciplinary research field with deep ramifications in different
areas of mathematics and physical sciences, such as crystallography and computational geometry, dynamical systems, and number theory. Due to the unprecedented
flexibility in their Fourier space, which can be designed to span across all possible
spectral singularity measures, engineered aperiodic structures provide unprecedented
opportunities to manipulate light states, scattering and localization phenomena for
nanophotonics technologies.
In this chapter, we presented a comprehensive overview of our own work on the
conceptual foundation, design, nanofabrication, and selected device applications of
aperiodic arrays of metallic nanoparticles generated by algorithmic rules, referred
to as Deterministic Aperiodic Nano-Structures. Specifically, we discussed relevant
structure-property relations, hot spots engineering rules and near-field enhancement
in a large number of nanoplasmonic arrays of Au nanoparticles with aperiodic Fourier
space. Specific device applications were presented in relation to optical biosensing,
plasmon-enhanced light sources, and solar cells, demonstrating that the distinctive
interplay between photonic diffraction and near field plasmonic localization in DANS
provides novel opportunities to manipulate light-matter interactions on the nanoscale.
In addition, we reviewed the fascinating scattering properties of a novel plasmonic
platform based on the engineering of aperiodic Vogel’s spirals, which offer broadband
planar diffraction, light emission enhancement and the generation and manipulation
L. D. Negro et al.
approximately a factor of 3 is measured for the GA spiral at 950 nm. The increase in
photocurrent results from the interplay of plasmonic-photonic effects in GA spirals,
which contribute to the overall enhancement as follows: by providing better coupling
of incident radiation into the thin Si layer due to photonic wide-angle scattering; by
enhancing the intensity of the nanoparticle near-fields at the Si interface owing to
better LSP coupling in the plane of the array compared to periodic structures. A
detailed comparison with optimized periodic grating structures in discussed in Ref.
[67].
We observe finally that the experimentally measured 31 % integrated enhancement
for GA spiral arrays has been demonstrated with only 25 % of the active photodetector
device area covered by GA arrays (Fig 9.21d, inset). These results highlight the
potential for even greater enhancement for complete device area coverage using
GA spirals. Moreover, in the context of thin-films absorption enhancement, a large
class of deterministic aperiodic spiral arrays with divergence angles different from
the golden angle remains to be explored, promising additional flexibility due to the
presence of multiple scattering rings in Fourier space [65].
9.4 Outlook and Conclusions
While light transport and localization phenomena in periodic and random structures
have been investigated for decades, the study of deterministic aperiodic structures is
still in its infancy. Deterministic aperiodic optical structures defines a novel, fascinating, and highly interdisciplinary research field with deep ramifications in different
areas of mathematics and physical sciences, such as crystallography and computational geometry, dynamical systems, and number theory. Due to the unprecedented
flexibility in their Fourier space, which can be designed to span across all possible
spectral singularity measures, engineered aperiodic structures provide unprecedented
opportunities to manipulate light states, scattering and localization phenomena for
nanophotonics technologies.
In this chapter, we presented a comprehensive overview of our own work on the
conceptual foundation, design, nanofabrication, and selected device applications of
aperiodic arrays of metallic nanoparticles generated by algorithmic rules, referred
to as Deterministic Aperiodic Nano-Structures. Specifically, we discussed relevant
structure-property relations, hot spots engineering rules and near-field enhancement
in a large number of nanoplasmonic arrays of Au nanoparticles with aperiodic Fourier
space. Specific device applications were presented in relation to optical biosensing,
plasmon-enhanced light sources, and solar cells, demonstrating that the distinctive
interplay between photonic diffraction and near field plasmonic localization in DANS
provides novel opportunities to manipulate light-matter interactions on the nanoscale.
In addition, we reviewed the fascinating scattering properties of a novel plasmonic
platform based on the engineering of aperiodic Vogel’s spirals, which offer broadband
planar diffraction, light emission enhancement and the generation and manipulation