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O: Fachverband Oberflächenphysik

O 14: Plasmonics and Nanooptics II: Light-Matter Interaction and Spectroscopy

O 14.6: Talk

Monday, March 18, 2024, 16:30–16:45, MA 042

Exploring the limits of refractive index sensing using Mie voids — •Micha Kappel, Serkan Arslan, Michelle Pfahl, Mario Hentschel, and Harald Giessen — 4th Physics Institute and Research Center SCoPE, University of Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany

The research of resonant phenomena using dielectric nanostructures, described by Mie's scattering theory, has enable new technologies in the field of nanophotonics. Resonant structures such as Mie voids have recently been realized, but have not been characterized in terms of their sensing potential.

To investigate their resonant features, the reflectance spectra are recorded via microspectroscopy. By inducing known refractive index changes inside the Mie voids by temperature change or liquid mixtures, the spectral shift of the resonances can be tracked by comparing the spectra at each refractive index. Comparing the resonances positions to a linear fit yields us the smallest measurable refractive index change.

For a 10 by 10 array of Mie voids with an overall volume of 11 fL, the smallest measurable refractive index change Δn is 0.00029 RIU. For a single Mie void with a volume of 520 aL, it is possible to detect a refractive index change Δn of 0.0049 RIU.

Using dielectric Mie voids we have realized the refractive index sensor the smallest sensing volume in the range of hundreds of attoliters. By using this technology, new applications in the field of biology and medicine could become possible, such as detecting neurotransmitters from single vesicles.

Keywords: Refractive index sensing; Mie scattering; Nanophotonics; Low sensing volume