9 Aperiodic Order in Nanoplasmonics
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similarity in direct space), and are typically characterized by a broader density of
spatial frequencies in Fourier space. 1
Deterministic aperiodic arrays of metal nanoparticles feature interparticle
separations that fluctuate from the nanoscale to distances comparable or larger than
the wavelength of light. As a result, they support a broad frequency spectrum of
“structural resonances”, or photonic–plasmonic coupled modes, which significantly
enhance the intensity of localized plasmon fields, as we will show later.
This book chapter is organized as follows: Sect. 9.2 introduces general aspects of
aperiodic order and the importance of aperiodic Fourier space for the manipulation of
plasmonic excitations. Section 9.3 focuses on the fabrication and device applications
of two-dimensional (2D) plasmonic DANS. Section 9.4 offers an outlook on complex
aperiodic nanoplasmonics and draws general conclusions.
9.2 Fundamentals of Deterministic Aperiodic Order
Aperiodic optical media generated by deterministic mathematical rules have recently
attracted significant attention in the optics and electronics communities due to their
simplicity of design, fabrication, and full compatibility with current materials deposition and device technologies [13–17]. Initial work, mostly confined to the theoretical
investigation of one-dimensional (1D) aperiodic systems [18–25], have succeeded
in stimulating broader experimental/theoretical studies on photonic and plasmonic
structures that leverage deterministic aperiodicity as a strategy to enable novel optical
devices and functionalities.
In what follows, we will introduce the conceptual framework of aperiodic order
for the manipulation of optical fields in complex nanoparticle arrays. Moreover, we
will discuss the relation between the topological order of DANS, determined by their
spectral measures (Fourier or diffraction spectra), and the general characteristics of
their optical spectra and plasmonic wave excitations (i.e., structure–property relations). This section will also serve as an introduction to the various types of array
geometries discussed in Sect. 9.3.
9.2.1 Periodic and Quasi-Periodic Order
Traditionally, optical media were simply classified as either periodic or non-periodic,
without the need of further distinctions. However, the word “non-periodic” encompasses a very broad range of different concepts that describe complex structures characterized by varying degrees of order and correlations, ranging from
1 However, inhomogeneous fractal structures (i.e., multi-fractals) described by a distribution of
scaling exponents can support a higher density of spatial frequencies compared to traditional monofractals, similarly to DANS.
331
similarity in direct space), and are typically characterized by a broader density of
spatial frequencies in Fourier space. 1
Deterministic aperiodic arrays of metal nanoparticles feature interparticle
separations that fluctuate from the nanoscale to distances comparable or larger than
the wavelength of light. As a result, they support a broad frequency spectrum of
“structural resonances”, or photonic–plasmonic coupled modes, which significantly
enhance the intensity of localized plasmon fields, as we will show later.
This book chapter is organized as follows: Sect. 9.2 introduces general aspects of
aperiodic order and the importance of aperiodic Fourier space for the manipulation of
plasmonic excitations. Section 9.3 focuses on the fabrication and device applications
of two-dimensional (2D) plasmonic DANS. Section 9.4 offers an outlook on complex
aperiodic nanoplasmonics and draws general conclusions.
9.2 Fundamentals of Deterministic Aperiodic Order
Aperiodic optical media generated by deterministic mathematical rules have recently
attracted significant attention in the optics and electronics communities due to their
simplicity of design, fabrication, and full compatibility with current materials deposition and device technologies [13–17]. Initial work, mostly confined to the theoretical
investigation of one-dimensional (1D) aperiodic systems [18–25], have succeeded
in stimulating broader experimental/theoretical studies on photonic and plasmonic
structures that leverage deterministic aperiodicity as a strategy to enable novel optical
devices and functionalities.
In what follows, we will introduce the conceptual framework of aperiodic order
for the manipulation of optical fields in complex nanoparticle arrays. Moreover, we
will discuss the relation between the topological order of DANS, determined by their
spectral measures (Fourier or diffraction spectra), and the general characteristics of
their optical spectra and plasmonic wave excitations (i.e., structure–property relations). This section will also serve as an introduction to the various types of array
geometries discussed in Sect. 9.3.
9.2.1 Periodic and Quasi-Periodic Order
Traditionally, optical media were simply classified as either periodic or non-periodic,
without the need of further distinctions. However, the word “non-periodic” encompasses a very broad range of different concepts that describe complex structures characterized by varying degrees of order and correlations, ranging from
1 However, inhomogeneous fractal structures (i.e., multi-fractals) described by a distribution of
scaling exponents can support a higher density of spatial frequencies compared to traditional monofractals, similarly to DANS.