Takao Tagiri

Near-Field Readout of 75 Gbyte Disc Made with Conventional Optical Disc Manufacturing Equipment

In this report, the results of the study of a 75 Gbyte (GB) disc for the solid immersion lens (SIL) system are presented. We used conventional mastering and molding equipment except for the recording process for the SIL disc. The electron beam recorder (EBR) was used as a signal recording machine for small pits. From the results of the experiments, we confirmed that conventional equipment could be used for high-density disc manufacture. The jitter value of the 75 GB disc was 9.5%.

Layer Stack Design of High Density Read-Only-Memory Discs for Near-Field Systems using a Solid Immersion Lens

For high numerical aperture (NA) near-field systems using a solid immersion lens, layer stack types of first-surface read-only-memory (ROM) discs have been investigated. Complicated interactions of high-NA incident and diffracted waves with surface waves occur in multilayer-stacked subwavelength structures on the discs. Therefore, vector diffraction simulation in consideration of these effects is indispensable for the optimization of the disc structures. We used rigorous coupled wave analysis to numerically calculate readout signals from the discs. On the basis of the simulation results, we actually fabricated high-density ROM media. Consequently, a significantly low jitter of 6.8% was obtained for 100 Gbyte ROM media with a designed structure in an NA 2.0 system.

Tin Alloy Nitride Write-Once Media for Solid Immersion Lens System

We studied a high-numerical-aperture (NA) solid immersion lens (SIL) system using tin alloy nitride write-once recording media with a protective cover layer. The jitter value of the disk that was recorded by this system was 8.5% at 100 GB capacity with a track pitch of 160 nm and a bit length of 56.25 nm. We confirmed the feasibility of the SIL-R disk using these recording media with the high-density recording SIL system.