Polarization Properties of Bent-type Optical Fiber Probe for Magneto-optical Imaging

T. Ishibashi, T. Yoshida, A. Iijima, K. Sato, Y. Mitsuoka and K. Nakajima
Proc. 5th Int. Conf. Near-Field Optics (NFO-5), Wakayama, Dec.6-10, 1998, J. Microscopy 194 Pt 2/3 (1999) 374-377

Quantitative evaluation of magneto-optical (MO) parameters is necessary in order to apply the SNOM technology to the study of magnetism in the mesoscopic scale. For this purpose quantitative knowledge of polarization transmission properties through optical fiber probe is required. We therefore determined the Stokes parameters of the bent-type optical fiber probe that is used as a cantilever for AFM operation in our SNOM system. As a result, it is found that the degree of polarization is maintained in the light emitted from the probe, although the probe acts as if it were a wave plate. This anisotropic polarization state of the light emitted from the probe was compensated by using the Berek compensator placed in front of the fiber coupler.
KEY WORDS: magneto-optical imaging, scanning near-field optical microscope, polarization modulation technique, bent-type optical fiber probe, Stokes parameter