Polarization-dependent optical responses of Sb-type near-field optical disk structure

The near-field and far-field optical properties of Sb-type near-field optical disk structures with different polarized situations are studied by finite-difference time-domain (FDTD) method. Localized surface plasmon enhancements are found around rough surface of Sb layers for TM polarized, but no near-field enhancement is found in cases with TE polarized incident waves. Far-field readout contrast signals of both TE and TM polarized situations show the superresolution capability, because evanescent signals of subwavelength recording marks are coupled to propagating waves by nanostructures (nano aperture or rough surface) in near-field active layer. Nevertheless, the contrast signals for TM illumination are higher than TE illumination due to localized surface plasmon enhancements. A simplified Fourier optics model is used to describe the relation between highly localized near-field distributions and enhanced resolution of far-field signals.