Spin polarization in near-field optical microscopy

The possibility of spin polarization and coherence detection is discussed theoretically as a strong coupling limit of a probe-tip-sample system in near-field optical microscopy and spectroscopy. A novel detection scheme is proposed, and the characteristic behavior is numerically analyzed on the basis of the field propagator method and density operator method for a nanometric probe-tip and a quasi-two-level sample system. It is shown that the spin polarization and coherence of the sample give different peak intensities and peak shifts of the near-field signal as a function of the probe-tip-sample distance, depending on the linear polarization of the probe beam. The results suggest that one may use the characteristics in order to sense a sample state.