Resonant optical antennas are ideal for nanoscale nonlinear optical interactions due to their inherent strong local field enhancement. Indeed second- and third-order nonlinear response of gold nanoparticles has been reported. Here we compare the on- and off-resonance properties of aluminum, silver, and gold nanoantennas, by measuring two-photon photoluminescence. Remarkably, aluminum shows 2 orders of magnitude higher luminescence efficiency than silver or gold. Moreover, in striking contrast to gold, the aluminum emission largely preserves the linear incident polarization. Finally, we show the systematic resonance control of two-photon excitation and luminescence polarization by tuning the antenna width and length independently. Our findings point to aluminum as a promising metal for nonlinear plasmonics.
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Nano Lett
January 2025
Department of Mechanical Engineering, the University of Texas at Dallas, Richardson, Texas 75080, United States.
Plasmonic nanomaterials are effective photoacoustic (PA) contrast agents with diverse biomedical applications. While silica coatings on gold nanoparticles (AuNPs) have been demonstrated to increase PA efficiency, the underlying mechanism remains elusive. Here, we systematically investigated the impact of silica coatings on PA generation under picosecond and nanosecond laser pulses.
View Article and Find Full Text PDFSci Adv
January 2025
NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland.
Magnonics, which harnesses the unique properties of spin waves, offers promising advancements in data processing due to its broad frequency range, nonlinear dynamics, and scalability for on-chip integration. Effective information encoding in magnonic systems requires precise spatial and temporal control of spin waves. Here, we demonstrate the rapid optical control of spin-wave transport in hybrid magnonic-plasmonic structures.
View Article and Find Full Text PDFLight Sci Appl
January 2025
Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware, 19716, USA.
Exceptional points (EPs) have been extensively explored in mechanical, acoustic, plasmonic, and photonic systems. However, little is known about the role of EPs in tailoring the dynamic tunability of optical devices. A specific type of EPs known as chiral EPs has recently attracted much attention for controlling the flow of light and for building sensors with better responsivity.
View Article and Find Full Text PDFSci Rep
January 2025
Department of Physics, University of Ottawa, Ottawa, ON, K1N 6N5, Canada.
We report a nonlinear terahertz (THz) detection device based on a metallic bull's-eye plasmonic antenna. The antenna, fabricated with femtosecond laser direct writing and deposited on a nonlinear gallium phosphide (GaP) crystal, focuses incoming THz waveforms within the sub-wavelength bull's eye region to locally enhance the THz field. Additionally, the plasmonic structure minimizes diffraction effects allowing a relatively long interaction length between the transmitted THz field and the co-propagating near-infrared gating pulse used in an electro-optic sampling configuration.
View Article and Find Full Text PDFNano Lett
January 2025
Institute of Experimental and Applied Physics, Kiel University, Leibnizstr. 11-19, Kiel 24098, Germany.
Topological plasmonics combines principles of topology and plasmonics to provide new methods for controlling light, analogous to topological edge states in photonics. However, designing such topological states remains challenging due to the complexity of the high-dimensional design space. We present a novel method that uses supervised, physics-informed deep learning and surrogate modeling to design topological devices for desired wavelengths.
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