Enhancing, controlling and guiding light with high refractive index dielectric nanoantennas

Optical antennas can transform light from freely propagating waves into highly localized excitations that interact strongly with matter. These nanoantennas are usually made of metallic nanostructures and employed to obtain... [ view full abstract ]

Optical antennas can transform light from freely propagating waves into highly localized excitations that interact strongly with matter. These nanoantennas are usually made of metallic nanostructures and employed to obtain strong light-matter interactions at subwavelength size scales (plasmonics). Metals show some limitations due to their inherent ohmic losses,leading to temperature increase in the nanoantenna and its surroundings. Another limitation of metals is the difficulty to generate optical magnetic response.

Nanoantennas made of High Refractive Index Dielectric (HRID) materials with low losses in the VIS and NIR ranges, can produce both, high near field enhancements and good scattering efficiencies, while showing magnetic response and low heat radiation. Here, we will show how HRID nanoantennas can act as basic units for the development of efficient light emitting devices aimed at integrated photonics, sensing and surface enhanced spectroscopic applications[1-2]. Also, we will discuss another key aspect of these nanostructures, which is the presence of coherent effects between electric and magnetic resonances. Then, by conveniently designing their shape and size, they can arbitrarily interfere to direct light towards a desired direction[3-5]. This opens new paths to control the way light propagates at the nanoscale, such as steering (on-chip wireless communications)[4-6],building operational switching devices[7], designing novel metamaterials[8],enhancing nonlinear effects[9] or improving the performance of solar cells[10-11].

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11. Barreda, A. I. et al. Sci. Rep., 8, 7976 (2018).