Home Technology Researchers report broadband tip-enhanced nonlinear optical response in a plasmonic nanocavity

Researchers report broadband tip-enhanced nonlinear optical response in a plasmonic nanocavity

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Researchers report broadband tip-enhanced nonlinear optical response in a plasmonic nanocavity

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Broadband tip-enhanced nonlinear optical response in a plasmonic nanocavity
Determine 1. (a) Schematic illustration of the experiment. Native SHG sign is enhanced by irradiating an infrared laser pulse into the plasmonic nanogap between the gold tip and the gold substrate. (b) SHG spectra obtained with (crimson) and with out (orange) plasmonic nanogap, indicating that the SHG sign is enhanced solely when the tip is introduced nearer because of the plasmonic enhancement impact distinctive to the tip-substrate nanocavity. Credit score: Toshiki Sugimoto

Squeezing gentle past the diffraction restrict and controlling the optical processes attributable to nano-confined gentle are central problems with nanophotonics. Specifically, localized and enhanced gentle on the plasmonic nanogaps in scanning probe microscopes gives us with a singular platform for acquiring site-specific optical data on the molecular/atomic scale.

Very not too long ago, not solely linear but in addition nonlinear optics have been utilized to such tip-enhanced nanoscopy to realize increased sensitivity and . On this context, understanding the intrinsic nonlinear optical properties of nanocavities is of rising significance in controlling nanosized extra exactly.

Researchers led by Toshiki Sugimoto, Affiliate Professor on the Institute for Molecular Science, succeeded in elucidating the intrinsic nonlinear optical properties of tip-substrate plasmonic nanocavities. Combining a wavelength-tunable femtosecond pulse laser system with a scanning tunneling microscope and specializing in the tip-enhancement of second harmonic technology (SHG), they reported an unexpectedly broad tip-enhanced nonlinear optical response in a plasmonic nanocavity (see determine 1).

Broadband tip-enhanced nonlinear optical response in a plasmonic nanocavity
Determine 2. (Higher panel) Scanning electron micrographs of the ideas used within the tip-enhanced SHG measurements. Zoomed-in views of the areas indicated by white squares in (a), (d), and (g) are proven in (b), (e), and (h), respectively. (Center panel) The intensities of tip-enhanced SHG obtained for the corresponding ideas. Structural variations in nanometer-scale tip apex and micrometer-scale tip shafts give rise to the variation within the spectral property of SHG enhancement. (Decrease panel) The excitation wavelength dependence of the tip-enhanced SHG depth calculated for the ideas proven within the higher panel. The calculated outcomes excellently seize the traits of the noticed tip-enhanced SHG. Credit score: Toshiki Sugimoto

They demonstrated that the tip-enhancement of SHG is maintained over the seen to (see determine 2a–c). Furthermore, the outstanding geometrical results of plasmonic ideas dominating this broadband enhancement means have been additionally verified; the broadband nonlinear optical property of tip-substrate nanocavities is considerably influenced not solely by the constructions of nanosized tip apexes but in addition by micrometer measurement tip shafts (see determine second–i).

The origin of those geometrical results was unveiled by exact numerical simulations of plasmonic fields inside tip-substrate nanocavities. They theoretically demonstrated that broadband tip-enhanced SHG properties might be considerably altered in response to nanometer- and micrometer-scale tip constructions. The simulations incorporating this structural data excellently seize the experimentally noticed habits (see determine 2j–l).

Extra detailed evaluation of those simulated outcomes revealed the origin of geometrical results on tip-enhanced SHG; whereas the micrometer-scale tip shafts prolong the spectral vary of the sector enhancement to the near- and mid-infrared areas, the nanometer-scale tip apexes primarily contribute to boosting seen/near-infrared gentle. This means that the micrometer-scale tip shafts and nanometer-scale tip apexes collectively allow the simultaneous enhancement of each mid/near-infrared excitation and visual/near-infrared radiation processes, respectively, realizing the strongly enhanced SHG over the seen to infrared broadband area.

This demonstration of the numerous broadband enhancement means of plasmonic nanogaps gives a brand new foundation for intentional management of site-specific nonlinear optical phenomena which might be basically accompanied by drastic wavelength conversion. Furthermore, the group’s findings pave the way in which for creating next-generation tip-enhanced nanoscopy by exploiting varied nonlinear optical processes.

Based mostly on these new strategies, correlated chemical and topographic data shall be efficiently addressed with final spatiotemporal decision, selling cutting-edge microscopic analysis in quite a lot of bodily, chemical and occurring in heterogeneous environments.

Extra data:
Shota Takahashi et al, Broadband Tip-Enhanced Nonlinear Optical Response in a Plasmonic Nanocavity, The Journal of Bodily Chemistry Letters (2023). DOI: 10.1021/acs.jpclett.3c01343

Quotation:
Researchers report broadband tip-enhanced nonlinear optical response in a plasmonic nanocavity (2023, July 31)
retrieved 1 August 2023
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