Spatial coherence of light measured by nanoscattering

As complex random electromagnetic fields are increasingly exploited in advanced photonics, the measurement of their statistical properties emerges as a crucial technical issue. For spatial coherence, we employ dipole scattering and report on a nano-optics counterpart of Young’s interferometer with the openings replaced by metallic dipolar nanoparticles. The results are in agreement with those obtained by other methods. The resolution is comparable to the size of the probes, well beyond that in standard techniques. While we consider here random optical beams, the two-probe method finds particular use in electromagnetic near-field optics where customary polarization elements cannot be employed.