Low-Loss Dielectric Nanoantennas for Surface-Enhanced Spectroscopies and Nonlinear Photonics

Event Date
Monday, 11 December 2017 - 12:00pm
Speaker/host external
Dr Gustavo Grinblat
Imperial College London

Venue: Room G01, Royal School of Mines, imperial College London.

Dr Gustavo Grinblat, Department of Physics, Imperial College London

Abstract: Dielectric nanoantennas have recently emerged as promising alternative candidates to plasmonic systems in the visible range.1 When excited above their bandgap energies, high-refractive-index dielectric nanostructures can highly concentrate electric and magnetic fields within subwavelength volumes while presenting ultra-low absorption compared to metals. In particular, by locally enhancing the incident light intensity, dielectric nanoantennas are expected not only to produce negligible heating, but also boost nonlinear phenomena and surface-enhanced spectroscopies, since their efficiencies increase with the excitation density.

In this presentation, Si, GaP and Ge nanoantennas will be introduced as promising nanosystems for surface-enhanced Raman and fluorescence spectroscopies, second and third harmonic generation at visible wavelengths, and four-wave mixing phenomena.2-6 Fluorescence enhancement factors of over 3000 and harmonic conversion efficiencies of 10-3% will be demonstrated for suitably engineered dielectric nanostructures. Finally, hybrid dielectric/metallic Si/Au nanoantennas will also be analysed.7

1 Albella, P.; Alcaraz de la Osa, R.; Moreno, F.; Maier, S. A. J. ACS Photonics 2014, 1, 524–529.

2 Caldarola, M; Albella, P; Cortés, E.; Rahmani M.; Roschuk, T.; Grinblat, G. et al. Nat. Commun. 2015, 6, 7915.

3 Grinblat, G.; Li, Y.; Nielsen, M., Oulton R. F.; Maier S. A. Nano Lett. 2016, 16, 4635-4640.

4 Grinblat, G.; Li, Y.; Nielsen, M., Oulton R. F.; Maier S. A. ACS Nano 2017, 11, 953–960.

5 Cambiasso, J.; Grinblat, G.; Li, Yi.; Rakovich, A.; Cortés, E.; Maier, S. A. Nano Lett. 2017, 17, 1219–1225.

6 Grinblat, G.; Li, Y.; Nielsen, M., Oulton R. F.; Maier S. A. ACS Photonics 2017, 4, 2144–2149.

7 Shibanuma, T.; Grinblat, G.; Albella, P.; Maier S. A. Nano Lett. 2017, 17, 2647-2651