Scanning near-field magneto-optic microscopy using illuminated fiber tips

By the implementation of a polarization-sensitive detector, a scanning near-field optical microscope (SNOM) can detect local magneto-optic effects with a high lateral resolution. The microscope used for the work presented in this article employs an aluminum-coated fiber tip as a sub-λ light source. Because such sources show a very poor quality of polarization, a sophisticated detector setup is necessary to eliminate the effects of the unpolarized background signal. As both the light transmitted through the sample or reflected from the sample surface can be detected, the Kerr and Faraday effect can be observed. Images were taken in transmission mode from thin iron-garnet films and in reflection mode from MnBiAl multilayers.