Manipulation of luminescence by Mie-resonances
The scattering of electromagnetic waves on spherical dielectric particles was first theoretically described by Gustav Mie more than 100 years ago. He already noticed several resonances (dipole, quadrupole, octupole …), which occurred in the scattering spectrum with increasing Particle size/wavelength ratio – the Mie resonances. Today the concept of Mie resonances is generalised to wave scattering from all kinds of particle shapes and the ability to create micro- and nanoparticles in all kinds of sizes and forms allows to also study these experimentally in much more detail. After a short overview of the general properties of Mie resonances I will focus in this talk on the impact of Mie-resonances on emitters. In particular I will describe, how the spontaneous emission of Ge-quantum dots (spectral range 1200 -1600nm), which are embedded in silicon disc /cylinders with a controlled height and diameter, are influenced by the Mie-resonances. In general an enhancement of luminescence at the Mie-resonances is observed. Time resolved luminescence measurements demonstrate, that this is at least partly caused by the Purcell effect, which accelerates the radiative transitions at the resonances. To increase the Purcell factor, collective Mie-resonances of trimers and periodic chains of dielectric discs are investigated leading to higher Q-factor resonances due to a partial cancellation of radiative losses in the far field. A systematic investigation of the spectral luminescence response from resonator chains with increasing number of individual resonators additionally indicates the importance of a smooth field envelope to reach Q-factors of several hundreds. Finally, I will relate these results to photonic crystal nanobeams and give an outlook to further concepts, how Mie resonances can be used to manipulate luminescence.
Der Vortrag wird zusätzlich online übertragen. Der Livestream des MMZ kann öffentlich und frei zugänglich unter folgender Adresse angeschaut werden: