Light scattering from silicon nitride microdisks

High intensity sub-wavelength spots and low divergence nanojets are observed in a system of Si₃N₄ microdisks illuminated with linearly polarised coherent light of wavelength 532 nm. The disks are of height 400 nm with diameters ranging from 1μm to 10μm. Light scattered from the disk and substrate is observed by imaging from above. In free space light is focused inside the disks and a sub wavelength spot is observed. The angular distribution of the intensity compares well to numerical 3D FEM results. The diameter and polarisation dependence of the scattering is explored and matches well with theory.