Chapter 6 - Optical super-resolution for ultra-high density optical data storage

Abstract

This chapter discusses optical super-resolution for ultrahigh density optical data storage. It introduces three different types of super-resolution near-field disks and their features. The chapter explains that type C super-resolution near-field structure (super-RENS) disk differs from the other disks, and indicates extremely high signal intensity and small resolution. Although the detailed mechanism has not yet been clearly understood, the chapter discusses that a simple aperture model is not applicable, but the super-resolution readout depends on the optical property at the edge of a phase-change boundary, and the generation of a huge number of composite diffracted evanescent waves (CDEWs) plays a role in the high signal intensity and resolution, rather than plasmonic enhancement. Type C super-RENS disk exhibits completely different features in readout, and in recording from the other disks. It is noticed that the top layer thickness is not sensitive to recording signals because pit recording is only active between the phase-change layer and the PtOx layer through the intermediate dielectric layers. The combination of plasmonic enhancement and type C super-RENS disk is analyzed in the chapter.