Lattice Resonances for Thermoplasmonics

Abstract

Thanks to their ability to support localized surface plasmons, metallic nanostructures have emerged as ideal tools to transduce light into heat at the nanoscale, giving birth to the field of thermoplasmonics. When arranged in a periodic array, the localized plasmons of metallic nanostructures can interact coherently to generate a collective mode known as a lattice resonance. This collective mode, whose wavelength is controlled by the periodicity of the array, produces a stronger and more spectrally narrow optical response than that of the localized plasmons supported by the individual nanostructures. Motivated by the exceptional properties of the lattice resonances of periodic arrays of metallic nanoparticles, here, we investigate their use for applications in thermoplasmonics. Through a comprehensive analysis based on a coupled dipole model, we show that arrays supporting a lattice resonance absorb more energy per nanoparticle, and thus achieve a much larger increase in temperature under pulsed illumination conditions, than those that do not support such a mode. On the contrary, for continuous wave illumination conditions, we find that the temperature increase is mostly independent of the array period for the systems under consideration. Furthermore, by analyzing arrays with two nanoparticles per unit cell, we show that it is possible to engineer their lattice resonances to selectively absorb light in one of the nanoparticles without exciting the other. The results of this work pave the way for the development of thermoplasmonics applications exploiting the exceptional optical response and tunability provided by lattice resonances.

Chiral Lattice Resonances in 2.5-Dimensional Periodic Arrays with Achiral Unit Cells

“…Importantly, the size of the nanoparticles forming the arrays under consideration are significantly smaller than a. Consequently, their localized plasmons are spectrally located far from the lattice resonances, thus ensuring that the latter are highly collective. 30,76 Furthermore, under these conditions, we can describe the optical response of the array using the well-established coupled dipole model (CDM). 4,5,9,77−80 Within this semianalytical approach, each nanoparticle is modeled as a point dipole with both electric and magnetic components, and the collective response of the array arises from the self-consistent mutual interaction between the dipoles.…”

“…90 The results of this work provide a strong theoretical understanding of the chiral response of the lattice resonances supported by structurally achiral 2.5-dimensional arrays, and therefore are expected to have far-reaching implications from an application point of view. For example, the dissymmetry in absorbance displayed by these systems upon excitation with light of different handedness could be exploited in thermoplasmonics applications 30 as a mechanism to control the heating of the array. Similarly, invoking reciprocity arguments, this same dissymmetry could be utilized to implement arrays emitting thermal radiation with nonvanishing optical helicity, 91 or, if supplemented with a gain medium, sources of chiral light.…”

“…17,18 Such exceptional properties have made lattice resonances the subject of an extensive research effort, which has resulted in the proposal and development of a wide range of applications. These include, among others, ultrasensitive biosensors, 19−21 color filters, 22,23 light-emitting devices, 24−28 light-to-heat transducers, 29,30 and even platforms to explore new physical phenomena. 31−36 More recently, lattice resonances have begun to be explored for applications involving chirality.…”

“…Periodic arrays of metallic nanostructures support collective electromagnetic modes commonly known as lattice resonances. − These modes, which appear in the spectrum at wavelengths commensurate with the periodicity of the array, are the result of the coherent multiple scattering between the individual constituents. , Due to their collective nature, lattice resonances give rise to very narrow optical responses, − with extraordinarily high quality factors for systems made of metallic nanostructures, − and couple strongly with light, − producing values of reflectance and absorbance that can reach the theoretical limits for two-dimensional systems. , Such exceptional properties have made lattice resonances the subject of an extensive research effort, which has resulted in the proposal and development of a wide range of applications. These include, among others, ultrasensitive biosensors, − color filters, , light-emitting devices, − light-to-heat transducers, , and even platforms to explore new physical phenomena. − …”

Surface Lattice Resonances in 3D Chiral Metacrystals for Plasmonic Sensing

“…Since it is known how the array size limits the possibility to observe SLRs, [ 31,32 ] in Figure S1 (Supporting Information), we also show how the c‐SLR intensity is significantly reduced when switching to a smaller array of 20 × 20 elements, corresponding to a patterned area of 100 µm 2 . The effect of increased size, up to 42 × 42 elements is also discussed in Section S1 (Supporting Information) and reported in Figure S1 (Supporting Information).…”