Influence of incident beam polarization on intensity and polarization distributions of tight focusing spot

Abstract

AbstractWe demonstrated theoretically and experimentally the influence of polarization of an input light beam on the intensity and polarization distributions of a tight focusing spot, obtained by a high numerical aperture (NA) objective lens (OL). The numerical calculations, based on vectorial Debye theory, show that, under tight focusing condition (NA = 1.4), the shape of the focusing spot varies as a function of the input beam polarization, resulting in either asymmetric or symmetric spots. A home made confocal microscope constituted by a high NA OL is employed to scan the fluorescence image of single gold nanoparticles showing the actual polarization dependence of focusing spot. The input linear polarization allows generating a small but asymmetric focusing spot, while the circular polarization produces a larger but symmetric one.