Talk by Prof. Pablo Albella: Plasmonic or non-plasmonic nanoantennas? It just depends

Plasmonic or non-plasmonic nanoantennas? It just depends

Prof. Pablo Albella
Department of Applied Physics (Group of Optics), University of Cantabria, Santander, Spain

Time: Thursday, Jan 23^rd at 14.15
Place: Dept. of Neuroscience & Biomedical Engineering (NBE), Aalto University, Rakentajanaukio 2C, Room: F336

ABSTRACT
Optical antennas convert freely propagating light waves into highly localized excitations that strongly interact with matter. Specifically, plasmonic nanostructures functioning as nanoantennas have been utilized to achieve strong light-matter interactions at deep subwavelength scales. However, their ohmic losses can cause temperature increases in the nanoantenna and its surroundings, a well-known effect beneficial for applications like photothermal imaging, drug delivery, certain biosensing techniques, and cancer therapy. Conversely, this effect limits the power deliverable to a hot spot before the particle reshapes or melts, impacting nanoscale lighting or the emission properties of nearby targets. Metals also face challenges in generating optical magnetic responses. Recently, low-loss resonators made from high permittivity dielectric materials (non-plasmonic) have emerged as effective alternatives for applications such as sensing (including enantiomers), spectroscopy (SERS or 

SEF), and designing light-emitting devices for integrated photonics or optical nanocircuits, where tuning light propagation direction enhances performance. In the first part of the talk, I will revisit and highlight the properties and strengths of plasmonic nanoantennas, focusing on our recent developments in novel nanoheaters capable of delivering heat asymmetrically, desirable in photothermal cancer therapies and drug delivery [1-4]. In the second part, I will discuss the weaknesses of plasmonic nanoantennas for certain applications and emphasize non-plasmonic nanoantennas as a way to overcome these weaknesses. These novel nanoantennas not only produce significant near-field enhancement and good scattering efficiencies but also offer intriguing optical properties, such as the ability to excite nanoscale displacement currents leading to magnetic responses [5,6]. This allows tuning the amplitude and phase difference of electric and magnetic resonances independently, paving the way for designing the next generation of nanoantennas that may be able to boost the actual Surface Enhanced Spectroscopies [7-8], light guiding [9-12], non-linear phenomena [13] or sensing applications, including chiral ones [14,15].

REFERENCES

1. J. González-Colsa, G. Serrera, J. M. Saiz, D. Ortiz, F. González, F. Bresme, F. Moreno and P. Albella. Optics Express 2022, 30(1), 125. 
2. J. González-Colsa, A. Franco, F. Bresme, F. Moreno and P. Albella. Sci. Rep 2022, 12(1), 14222. 
3. J. González-Colsa, A. Kuzyk and P. Albella. Small Structures 2024, 2300523. 
4. J. González-Colsa, J. D. Olarte-Plata, F. Bresme and P. Albella. J.Phys.Chem.Lett. 2022, 13(26), 6230. 
5. A. Barreda, J. M. Saiz, F. González, F. Moreno and P. Albella. AIP Advances 9, 040701 (2019). 
6. P. Albella, A. M. Poyli, M. Schmidt, S. A. Maier, F. Moreno, J. J. Sáenz and J. Aizpurua. J. Phys. Chem. C 2013, 117, 26, 13573–13584 
7. P. Albella, R. Alcaraz de la Osa, F. Moreno and S. A. Maier. ACS Photonics, 1 (6), 524–529, (2014). 
8. M. Caldarola, P. Albella*, E. Cortés, M. Rahmani, T. Roschuk, G. Grinblat, R. Oulton, Andrea V. Bragas and Stefan A. Maier. Nature Comms 6:7915, (2015). 
9. Pablo Albella, T. Shibanuma and Stefan A. Maier. Sci. Reports 5, 18322 (2015) 
10. T. Shibanuma, T. Matsui, J. Wojcik, P. Mascher, P. Albella and S. A. Maier. ACS Photonics 4 (3), 489– 494, 2017. 
11. T. Shibanuma, T. Matsui, J.Wojcik, P. Mascher, P. Albella and S. A. Maier. ACS Photonics 4, 489, 2017. 
12. T. Shibanuma, Stefan A. Maier and P. Albella. Appl. Phys. Lett. 112 (6), 063103, 2018 
13. T. Shibanuma, G. Grinblat, P. Albella and S. A. Maier. Nano Lett. 17 (4), 2647–2651, 2017.
14. G. Serrera, J. González-Colsa, V. Giannini, J. M. Saiz and P. Albella. Journal of Quantitative Spectroscopy & Radiative Transfer 284 (2022) 108166. 
15. G. Serrera, J. González-Colsa and P. Albella. Appl. Phys. Lett. 124, 251701 (2024).