Physical model for near-field scattering and manipulation

Abstract

We present a physical model for the conversion of the evanescent photons into propagating photons detectable by an imaging system. The conversion mechanism consists of two physical processes, near-field Mie scattering enhanced by morphology dependant resonance and vectorial diffraction. For dielectric probe particles, these two processes lead to the formation of an interference-like pattern in the far-field of a collecting objective. The detailed knowledge of the far-field structure of converted evanescent photons is extremely important for designing novel detection systems. The model is also applicable for determination of the near-field force exerted on small particles situated in an evanescent field. This model should find broad applications in near-field imaging, optical nanometry and near-field metrology.