Abstract

Magneto-optical disk systems have recently been put into the market, featuring large capacity of 600 MB on a double-sided 5.25 inch disk.¹ However the system does not have a function of direct overwriting, i.e., erasing operation must be carried out before writing. There is an increasing demand for direct overwriting to obtain an effectively high data transfer rate. Various methods² for achieving overwriting have been investigated, including the magnetic field modulation method³ and the light intensity modulation method.⁴ Two light intensity levels P_U and P_L are used in the light intensity modulation method. It has the advantages in terms of a high transfer rate and a wide magnet-disk spacing compared with the magnetic field modulation method. The light intensity modulated overwriting was successfully reported by Saito et. al.⁴ using an exchange-coupled double layer film.

© 1989 Optical Society of America