Pablo Albella University of Cantabria Spain

 

Brief Bio
Pablo Albella is Associate Professor of Optics in the Department of Applied Physics at the University of Cantabria where he leads different research lines within the area of nano-optics, thermoplasmonics, chiral sensing and optical forces are the main ones. He is also visiting Researcher in the Department of Chemistry at Imperial College London. He obtained his PhD in late 2009, awarded with the prize of best thesis in physics that year. Following his PhD, he completed two postdoctoral stays: one at the Materials Physics Center (CFM) in San Sebastian where he also held a Guest Researcher Position at CIC Nanogune, and a four-year one at Imperial College London. In 2017, he obtained an Excellence Researcher position from the Government of the Canary Islands to join a research institute and create a research group in Nanophotonics. Subsequently, in June 2018, he gained a Ramón y Cajal tenure track position. Mention, that he is the founder and organizer of an International Nanophotonics workshop on Nanophotonics, Plasmonics and Metamaterials (NanoPlasMeta) that takes place in conjunction with this conference since 2019.

Abstract

Plasmonic nanostructures acting as nanonantennas have been employed to obtain strong light-matter interactions at deep subwavelength size scales [1]. However, its ohmic losses lead to temperature increase in the metal and surroundings. This effect is well known and some applications take advantage of it, such as photothermal imaging or cancer therapy. However, for other applications, it is detrimental as it strongly limits the power that can be delivered to a hot spot before the particle reshapes or melts, affecting its nanoscale lighting or the emission properties of molecules near the nanoantennas [2]. Apart from that, another strong limitation of metals is the difficulty to generate optical magnetic response. In the first part of the talk, I will show how low-loss resonators made of high refractive index (HRI) dielectric materials (non-plasmonic), can be very efficient in enhancing the interaction of light with molecules. In fact, they can produce both, large near field enhancement and good scattering efficiencies while generating small temperature increases in their hot spots and surrounding environments [3,4]. Another important aspect of these nanoantennas that will be discussed, is the presence of nanoscale displacement currents that lead to magnetic response [5]. This interesting property allows the tuning of amplitude and phase difference of electric and magnetic resonances independently. Then, by just conveniently designing the shape and size of the nanostructures, they can arbitrarily interfere providing with a new tool to control light. Moreover, metasurfaces that use one of this optimized nanostructures as unit-cell, can be built to also control light in a more practical manner [6]. The second part of the talk will be devoted to show how HRI dielectric cell-units can also be designed to increase the effects of chirality. All this show HRI dielectric nanoantennas as key units for the development of more efficient light emitting devices aimed at integrated photonics, (bio-) sensing, spectroscopic techniques (SERS or SEF) or optical nanocircuits, where tuning the light propagation direction and the enhancement of light with reduced losses would be beneficial to improve its performance.

References

[1] P. Mühlschlegel et al, Science, 308 (5728), (2005), 1607-9.

[2] Baffou, G. & Quidant, R. Laser Photon. Rev. 7, 171–187 (2013).

[3] P. Albella et al, J. Phys. Chem. C 117, (2013), 117, 13573–13584

[4] M. Caldarola, P. Albella et al, Nat. Commun. 6, (2015), 7915.

[5] J.M. Geffrin et al, Nature communications, 3, 1171 (2012)

[6] T. Shibanuma et al., Applied Physics Letters, vol. 112, p. 063103, 2018