Cross polarization of nano-objects located on a flat substrate in the presence of a glass microparticle

Abstract

In this work, we theoretically show that the deep subwavelength objects located on a dielectric substrate under a glass microcylinder sufficiently close to its bottom point are strongly polarized in the direction that is radial with respect to the microcylinder. This is even in the case when the structure is illuminated by the normally incident light. Though the incident electric field in the area of the objects is polarized almost tangentially to the cylinder surface, a significant cross polarization arises in the object due to its near-field coupling with the cylinder. In accordance with our previous works, the radial polarization is the key prerequisite of the super-resolution granted by a glass microsphere. Extending our results to the 3D case, we claim that the same cross-polarization effect should hold for a glass microsphere. In other words, the reported study shows that the parasitic spread image created by the tangential polarization of the objects should not mask the subwavelength image created by the radial polarization.

Roadmap on Label‐Free Super‐Resolution Imaging

“…However, simulations of ref. [671] show that this veiling effect is weak. Near‐field interaction between the sphere and the object makes the normal polarization of the last one dominant even in the case when the structure is illuminated by the normally incident light.…”