Light–Matter Interaction within Extreme Dimensions: From Nanomanufacturing to Applications

Abstract

Light-matter interaction lies at the heart of photonics/optical material science. As the research emphasis in recent years shifted from microscale towards nanoscale, light-matter interaction within extreme dimensions raised new challenges as well as opportunities. However, due to the diffraction limit of conventional optics, coupling and confinement of light into deepsubwavelength volume is usually very challenging, resulting in difficulties in exploring the lightmatter interaction within ultra-thin and ultra-small dimensions. Based on recent advances in theoretical modeling, nanomanufacturing and experimental validation efforts, unique features have been recognized. Here we summarize recent key progresses of light-matter interaction within extreme dimensions and discuss future directions based on new combinations of materials, structures, nanomanufacturing and applications, ranging from quantum plasmonics, nonlinear optics to optical biosensing.

Symmetric Meta‐Absorber‐Induced Superchirality

“…Light-matter interaction within extremely small dimensions received extensive interest over the past decades. [34] For instance, when metallic nanospheres were placed on metal films with ultra-small gaps, a volume charge density spreads out from the metal surface at the Angstrom level distance, which will set an upper limit for localized field enhancement in sub-nanometer length systems. [35,36] Three-layered MDM architecture is a promising candidate to approach this theoretical upper limit due to its super absorbing feature.…”

“…In addition, the newly developed atomic layer deposition lithography is another potential large-area strategy to realize the ultrasmall gaps. [34,37]…”

“…For example, advanced top down lithography technologies like helium‐ion beam milling can realize the resolution of ≈5 nm, better than the regular focused ion beam milling based on gallium‐ions. In addition, the newly developed atomic layer deposition lithography is another potential large‐area strategy to realize the ultra‐small gaps …”

Continuously-tunable Cherenkov-radiation-based detectors via plasmon index control

“…Recent developments in the control and manufacturing of nanostructures (NSs) [8][9][10] enabled particle detectors based on metal nanostructures (MNSs) [11][12][13]. CR near a thin metal film deposited on dielectric [11] and periodic structures [14][15][16] of metallic nanoarrays [17][18][19] are very different from a medium of a uniform index.…”

Large‐Scale Sub‐1‐nm Random Gaps Approaching the Quantum Upper Limit for Quantitative Chemical Sensing

“…Significantly enhancing localized optical fields enable investigation of light–matter interaction within deep‐subwavelength dimensions. [ 1–4 ] Smaller gaps between metallic structures will generally result in stronger localized field towards the quantum enhancement upper limit determined by the tunneling current introduced by free electrons across the gap. [ 5–10 ] For instance, it has been recognized that nano‐bowtie‐antenna can support highly enhanced localized fields at the 20‐nm‐wide gap between tips.…”