Over 15-GB Capacity Domain Wall Displacement Detection Magneto Optical Recording Using a Digital Versatile Disc Dimensional Optical Head

Abstract

High-density magneto-optical (MO) recording using a land/groove structured domain wall displacement detection (DWDD) medium has been achieved with a digital versatile disc (DVD) dimensional optical head including a 664-nm wavelength laser diode and a 0.60-NA objective lens. Due to the deep groove depth, easy domain wall displacement is obtained without the use of a track boundary postannealing process. Sufficient readout performance is obtained in experiments at an areal recording density of 11 Gbit/inch2, which is obtained using a 0.13-µm bit length and a 0.45-µm track pitch. This areal density corresponds to a capacity of 15 GB per one 120-mm-diameter disk.

Domain Wall Displacement Detection Mini Disc with Land/Groove Recording Applied to Mini Disc Systems

“…1. We believe that deeper [2] grooves cause this discontinuity of film deposition and the change of magnetic characteristics at the slope, which has the same effect as the nonmagnetic treatment. Because of the effect of the discontinuity at the boundary between groove and slope, it is believed that the wall on the land track will move together with that on the adjacent slope areas, while the wall in the groove remains independent.…”

“…We adopted the recording method of laser strobe magnetic field modulation and data coding of (1, 7) RLL. Data detection was performed by PR (1, -1) +Viterbi using the signal equalized [2] to PR(1, -1) of MO read-out.…”