Abstract
Abstract Plasmonic nanostructures can concentrate light and enhance light-matter interactions in the subwavelength domain, which is useful for photodetection, light emission, optical biosensing, and spectroscopy. However, conventional plasmonic devices and systems are typically optimized for the operation in a single wavelength band and thus are not suitable for multiband nanophotonics applications that either prefer nanoplasmonic enhancement of multiphoton processes in a quantum system at multiple resonant wavelengths or require wavelength-multiplexed operations at nanoscale. To overcome the limitations of “single-resonant plasmonics,” we need to develop the strategies to achieve “multiresonant plasmonics” for nanoplasmonic enhancement of light-matter interactions at the same locations in multiple wavelength bands. In this review, we summarize the recent advances in the study of the multiresonant plasmonic systems with spatial mode overlap. In particular, we explain and emphasize the method of “plasmonic mode hybridization” as a general strategy to design and build multiresonant plasmonic systems with spatial mode overlap. By closely assembling multiple plasmonic building blocks into a composite plasmonic system, multiple nonorthogonal elementary plasmonic modes with spectral and spatial mode overlap can strongly couple with each other to form multiple spatially overlapping new hybridized modes at different resonant energies. Multiresonant plasmonic systems can be generally categorized into three types according to the localization characteristics of elementary modes before mode hybridization, and can be based on the optical coupling between: (1) two or more localized modes, (2) localized and delocalized modes, and (3) two or more delocalized modes. Finally, this review provides a discussion about how multiresonant plasmonics with spatial mode overlap can play a unique and significant role in some current and potential applications, such as (1) multiphoton nonlinear optical and upconversion luminescence nanodevices by enabling a simultaneous enhancement of optical excitation and radiation processes at multiple different wavelengths and (2) multiband multimodal optical nanodevices by achieving wavelength multiplexed optical multimodalities at a nanoscale footprint.
Highlights
We summarize the recent advances in the study of the multiresonant plasmonic systems with spatial mode overlap
We refer to this type of plasmonic systems as “multiresonant plasmonic systems with spatial mode overlap” (Figure 1), which are able to achieve nanoscale enhancement of light-matter interactions in multiple different wavelength ranges at the same locations
We aim to present an overview of the theoretical background and experimental demonstrations of “multiresonant plasmonic systems with spatial mode overlap” and discuss the implications and opportunities in this research direction
Summary
Plasmonic devices and systems based on bottom-up synthesized or top-down fabricated metal nanostructures can be used to enhance light-matter interactions at nanoscale in physical, chemical, and biological systems [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19]. On the basis of the mode hybridization strategy [38, 39], it is possible to create multiresonant plasmonic systems based on closely assembled plasmonic building blocks, in which the associated elementary modes in the building blocks can strongly interact to form multiple new hybridized plasmonic modes at different wavelengths with spatial mode overlap. We refer to this type of plasmonic systems as “multiresonant plasmonic systems with spatial mode overlap” (Figure 1), which are able to achieve nanoscale enhancement of light-matter interactions in multiple different wavelength ranges at the same locations.
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