Near-field phase-change optical recording over 1.2 numerical aperture

Abstract

Recently, solid immersion lenses (SILs) have yielded a great interest in near-field optical data storage. However, convincing data on areal recording density have yet to be reported. The difficulty is attributed to the fact that an air-bearing slider needs to be kept optically contacted and also that a tiny SIL is vulnerable to aberrations caused by an air gap between a lens and a disk. The air-bearing system cannot easily achieve the condition above because its linear velocity changes the air gap. We have developed a new SIL device mounted on an actuator, which allows the air gap to be varied arbitrarily and enables optical contact independent of disk rotation. The obtained eyepattern of (l,7)-coded data on a phase-change disk demonstrates near-field recording over 1.2- numerical-aperture (NA).