The optical and electrical characteristics of electrically-driven nanogap antennas are extremely sensitive to the nanogap region where the fields are tightly confined and electrons and photons can interplay. Upon injecting electrons in the nanogap, a conductance channel opens between the metal surfaces modifying the plasmon charge distribution and therefore inducing an electrical tuning of the gap plasmon resonance. Electron tunneling across the nanogap can be harnessed to induce broadband photon emission with boosted quantum efficiency. Under certain conditions, the energy of the emitted photons exceeds the energy of electrons, and this overbias light emission is due to spontaneous emission of the hot electron distribution in the electrode. We conclude with the potential of electrically controlled nanogap antennas for faster on-chip communication.
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http://dx.doi.org/10.1515/nanoph-2023-0099 | DOI Listing |
Phys Rev Lett
December 2024
Center of Single-Molecule Sciences, Institute of Modern Optics, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, Nankai University, Tianjin 300350, China.
Via conductance measurements of thousands of single-molecule junctions, we report that the π-π coupling between neighboring aromatic molecules can be manipulated by laser illumination. We reveal that this optical manipulation originates from the optical plasmonic gradient force generated inside the nanogaps, in which the gapped antenna electrodes act as optical tweezers pushing the neighboring molecules closer together. These findings offer a nondestructive approach to regulate the interaction of the molecules, deepening the understanding of the mechanism of π-π interaction, and open an avenue to manipulate the relative position of extremely small objects down to the scale of single molecules.
View Article and Find Full Text PDFNanoscale
December 2024
Birla Institute of Technology and Science-Pilani, Pilani campus, Pilani-333031, Rajasthan, India.
End-to-end linked nanorod dimer nanogap antennas exhibit superior plasmonic enhancement compared to monomers due to the coupling of localized surface plasmon resonances (LSPR) of individual nanorods. However, controlling the assembly to stop at the dimer stage is challenging. Here, we report a pH-controlled synthesis of Au nanorod dimer nanogap antennas in an aqueous solution using 1,4-dithiothreitol (DTT) as a linker.
View Article and Find Full Text PDFACS Nano
January 2024
School of Physics and Technology and Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072, China.
Quantum tunneling, in which electrons can tunnel through a finite potential barrier while simultaneously interacting with other matter excitation, is one of the most fascinating phenomena without classical correspondence. In an extremely thin metallic nanogap, the deep-subwavelength-confined plasmon modes can be directly excited by the inelastically tunneling electrons driven by an externally applied voltage. Light emission via inelastic tunneling possesses a great potential application for next-generation light sources, with great superiority of ultracompact integration, large bandwidth, and ultrafast response.
View Article and Find Full Text PDFACS Nano
November 2023
Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, AMUTech, 13013 Marseille, France.
Plasmonic optical nanoantennas offer compelling solutions for enhancing light-matter interactions at the nanoscale. However, until now, their focus has been mainly limited to the visible and near-infrared regions, overlooking the immense potential of the ultraviolet (UV) range, where molecules exhibit their strongest absorption. Here, we present the realization of UV resonant nanogap antennas constructed from paired rhodium nanocubes.
View Article and Find Full Text PDFNanophotonics
April 2024
Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea.
Probing the time evolution of the terahertz electric field within subwavelength dimensions plays a crucial role in observing the nanoscale lightwave interactions with fundamental excitations in condensed-matter systems and in artificial structures, such as metamaterials. Here, we propose a novel probing method for measuring terahertz electric potentials across nanogaps using a combination of optical and terahertz pulse excitations. To achieve this, we employ ring-shaped nanogaps that enclose a metallic island, allowing us to capture tunneling charges when subjected to terahertz electromagnetic pulse illumination.
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