Media and systems of optical data storage: Investigations of magneto-optical and phase change recording techniques

Abstract

This dissertation contains studies on some aspects of the media and system in the optical data storage. The main subjects that have been examined are the magneto-optical (MO) media, phase-change (PC) media, and the effect of substrate birefringence on the optical system used in recording and readout. In the studies of the MO media, we concentrate on the magnetic properties of the groove edge (sidewall) and compute the coercivity caused by the edge of a terrace. Comparing the computer-simulation results with data obtained from the Kerr-loop measurement, we realize the distribution of the easy axis for films with oblique deposition. Concerning the material characterization, we employ the micro-Hall effect measurements to trace the domain-size variation during the thermomagnetic recording process. In the investigations of phase-change media, a new technique to determine the specific heats, thermal conductivities, and phase-transition temperature for non-erasable media is developed. On the subject of substrate birefringence, we describe a novel method to measure the substrate's vertical birefringence. We also examine the effects of birefringence on the signal obtained in an MO readout system as well as the image contrast in magnetic domain observations through the substrate.