Polarization effect in scanning near-field optic/atomic-force microscopy (SNOM/AFM)

The polarization effect is reported using a bent optical fiber probe for a scanning near-field optic/atomic-force microscope (SNOM/AFM). We have demonstrated that the SNOM/AFM could be applied to the observation of magnetic domains by imaging polarization contrast in transmission mode. An optical fiber probe with a subwavelength aperture is bent and vibrated vertically as a cantilever for an atomic-force microscope (AFM) for atomic-force regulation. Plane polarized light with an extinction ratio of better than 70 : 1 was emitted by the aperture of the bent probe by controlling the polarization properties of incident light to the probe. By detecting a particular transverse polarization component of light transmitting a sample selected by a polarization analyzer, we obtained clear polarization contrast images of 0.7 μm length bits written on a bismuth-substituted dysprosium-iron-garnet film.