Abstract

Domain wall displacement detection (DWDD[1]) is the most useful method to realize high linear density without using a blue laser or a lens of a high numerical aperture (NA). The authors previously reported the DWDD magneto optical (MO) medium applied to MiniDisc (MD) system[2]. Land-groove recording was used in the system with a 660 nm-laser and a lens of 0.52 NA. Wide laser power margins were obtained at 6.17 Gbit/in² equivalent to 2.0 GB capacity per side in MD size using a land-groove substrate with a deep groove. The DWDD MO medium did not require an annealing process for good signal properties. We call this type of DWDD medium an “anneal-less” DWDD medium. Birukawa et al. reported 3.0 GB per side in 2 inch-diameter disc with groove recording[3]. They shortened the track pitch using a sampled servo technique and realized 80 nm/bit with annealing process.

© 2003 Optical Society of America