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9LD-I-7
LASER DIAGNOSTICS AND SPECTROSCOPY
Novel physical method for 2-D chiral metasurfaces formation
D.R. Dadadzhanov1, I.A. Gladskikh1, R.A. Zakoldaev1, N.A. Toropov1-2, A.A. Starovoytov1 and T.A. Vartanyan1
1 - School of Physics and Engineering, ITMO University, St. Petersburg, Russia 2 - Living Systems Institute, University of Exeter, Exeter EX4 4QD, United Kingdom e-mail: daler.dadadzhanov@gmail.com
The ongoing drive in nanophotonics towards the search of new nanomaterials to manipulate the polarization properties of light is an urgent task. Of particular interest are chiral plasmonic nanostructures that support the collective oscillation of free electron in the response of incident electromagnetic wave. Chirality in plasmonic nanostructures originates from a unique natural effect in chiral molecules when the mirror images of which cannot be superimposed on each other. From a physical point of view, chirality in plasmonic nanostructures can be described based on coupling between electric and magnetic dipole moments, which specifically interact with left-/right-handed circularly polarized light unlike achiral nanostructures. This allows the use of chiral nanoparticles as optical light modulators, sensors, and even novel lasing sources. Recent studies, including "bottom-up" and "top-down" approaches, show diversity of the chiral plasmonic nanostructures such as metasurface of nanohelices or nanocrescent, helicoides synthesized by combination achiral nanoparticles and chiral precursors molecules, chiral gold nanostructures prepared by asymmetric photo-catalytic metal deposition [1, 2]. However, existing methods are very costly as in case of electron beam and focused ion beam lithography or required sophisticated multistep synthesis procedure. Thus, the searching of alternative strategies for fabrication of chiral plasmonic nanostructures are high demand. We propose a more promising strategy to increase the chiroptical properties of 2D plasmonic nanostructures by applying the spectral hole burning method [3-5] of plasmonic nanostructures with the broadband extinction spectra by pulse laser with circular polarization of radiation. The influence of high-power circular polarized laser irradiation on the optical properties of metasurfaces with self-organized silver nanoparticles obtained using the physical vapor deposition technique was studied. Optimal irradiation parameters at which there is no ablation of silver nanoparticles were established. The results obtained demonstrate strong sign-alternating circular dichroism in the spectral region of the incident radiation wavelength (532 nm) for annealed plasmonic nanostructures, as well as for broadband unannealed metasurface.
This work was supported by the Russian Science Foundation (Project 21-72-10098).
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[5] Bosbach, J., et al. "Spectral hole burning in absorption profiles of metal nanoparticles prepared by laser assisted growth." The European Physical Journal D-Atomic, Molecular, Optical and Plasma Physics 16.1 (2001): 213-217.
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