Enhancing magnetic light emission with optical nanoantennas
Electric and magnetic optical fields carry the same amount of energy. Nevertheless, the efficiency with which matter interacts with electric optical fields is commonly accepted to be at least 4 orders of magnitude higher than with magnetic optical fields . Here we experimentally demonstrate that properly designed photonic nanoantennas (figure 1a and b) can selectively manipulate the magnetic versus electric emission of luminescent nanocrystals . In particular, an enhancement of magnetic emission from trivalent europium-doped nanoparticles can only by observed in the vicinity of nanoantennas featuring a magnetic resonance [2,3]. Moreover, by controlling the spatial coupling between emitter and nanoresonator using a Near-field Scanning Optical Microscope (NSOM), local distributions of both magnetic and electric radiative local densities of states can be readily recorded with nanoscale precision (figure 1c and d), revealing the modification of the quantum environment induced by the presence of the nanoantennas. This manipulation and enhancement of magnetic light and matter interactions is a turning point in nanophotonics, opening up new possibilities for the research fields of opto-electronics, chiral optics, nonlinear nano-optics, spintronics and metamaterials, amongst others.