Phase properties of the optical near field

This paper presents a theoretical and numerical study of the phase properties of the optical near field. A model based on the first Rytov approximation for three-dimensional electromagnetic vector fields describes the relationship between the phase variations and both the topographic and optical properties of the scatterer. It is shown that strong polarization effects can lead to subwavelength phase variations around nanometric structures. The conclusions of the model are illustrated by exact numerical calculations. This study should find broad experimental applications in near-field optical interferometric phase measurements.