Polarization-resolved imaging with a reflection near-field optical microscope

Abstract

Using a rigorous microscopic point-dipole description of probe–sample interactions, we study imaging with a reflection scanning near-field optical microscope. Optical content, topographical artifacts, sensitivity window—i.e., the scale on which near-field optical images represent mainly optical contrast—and symmetry properties are considered for optical images obtained in constant-distance mode for different polarization configurations. We demonstrate that images obtained in cross-polarized detection mode are free of background and topographical artifacts and that the cross-circular polarization configuration is preferable to the cross-linear one, since it ensures more isotropic (in the surface plane) near-field imaging of surface features. The numerical results are supported with experimental near-field images obtained by using a reflection microscope with an uncoated fiber tip.