Readout contrast beyond diffraction limit by a slab of random nanostructures.

A simplified Fourier optics approach is applied to study how near-field optical disks retrieve evanescent signals through random nanostructure. The statistical properties of the random nanostructures are used to realize the general behavior of near-field optical disks. The mechanism of its super-resolution capability and an analytical expression of the readout contrast of near-field optical disks with random apertures are derived. The resolution of near-field optical disk is determined by the size of the random nanostructure.

Near- and far-field optical properties of embedded scatters in AgOx-type super-resolution near-field structures.

In recent near-field optical recording techniques, the super-resolution near-field structures (super-RENS) have been successfully demonstrated to overcome the diffraction limit. To realize the possibility of replacing the conventional near-field optical probe by the super-RENS, and to understand the relations between the near-field enhancements and detectable far-field signals, we use the two-dimensional finite-difference time-domain (FDTD) method to study the near-field and far-field properties of different types of embedded scatters in the AgOx-type super-RENS.