Subwavelength imaging of collective modes in silicon nanopillar honeycomb lattices

Dielectric Mie resonators enable resonant light coupling into nanoscale volumes with low loss and therefore have had significant impact as antenna motifs for dielectric metasurfaces. They hold promise for diverse applications including optical interconnects, bioimaging and metasurface. We investigate coupling between silicon Mie resonators using angle-resolved cathodoluminescence (CL) microscopy and spectroscopy. Silicon resonators arranged in monomer, dimer, hexamer and honeycomb lattice configurations with <50nm features on 10nm free standing Si₃N₄ membranes yield sharp, high quality coherent cathodoluminescence images upon electron beam excitation of optical resonances. We directly visualize redistribution of optical modes resulting from hybridization between resonances in individual Mie resonators. Using angle resolved Fourier space cathodoluminescence spectroscopy measurements, we observe photonic band structures that can be excited selectively at specific frequencies and lattice sites. Our experiments show clear evidence that collective modes can be excited in arrays of dielectric Mie resonators, and the image and spectroscopy results illustrate these features with high spatial, spectral and angular resolution.