Abstract

In 1987, we presented a direct overwritable Magneto-Optical exchange coupled multilayered (DOW-MO-ECML or DOW) disk by laser power modulation recording.¹⁾ The direct overwriting method could be summarized as follows.

(a) The ECML thin film has at least two layers as shown in Fig. 1. The upper layer, memory layer has higher coercivity at ambient temperature and lower Curie temperature than the lower layer, writing layer.

(b) Laser power is modulated as shown in Fig. 2. Ph irradia tion records new marks. Pl irradiation erases prerecorded marks. Pr means reading power.

(c) The initializing field, Mini is applied to the disk in ad dition to the bias field, Hb for recording.

© 1991 Optical Society of America