Metallic nanoparticles (NPs) are well-known for their strong interaction with electromagnetic radiation. Regarding spontaneous emission enhancement, these nanostructures have been suggested as an alternative to conventional optical cavities, which typically have a limited Purcell effect due to their relatively large mode volume. This means that large Q-factors are necessary in order to achieve high Purcell factors, leading to a narrow linewidth of the cavity resonance and thus a small emission bandwidth. In contrast to this situation, the electromagnetic response of nanoparticle-based resonances is broadband and enables ultra-small mode volume. However, although metallic nanoantennas seem to be a good candidate for emission enhancement, their inherent Ohmic losses limit their applicability and performance.
On the contrary, NPs made of High Refractive Index Dielectric (HRID) materials exhibit negligible absorption in the VIS-NIR spectral ranges. In addition, they present magnetic response, and can be designed to control the direction of the scattered radiation. Another remarkable difference compared to metallic NPs is that the Q-factor is mainly limited by radiation damping instead of the Joule losses.
It is the goal of our work to enhance the emission of quantum emitters by means of different configurations: low-loss Mie-resonant nanoantennas supporting complex near- and far-field interference phenomena, hybrid metal-dielectric nanoantennas, dielectric metasurfaces or hybrid photonic-plasmonic cavities.