Demonstration of high data density recording on direct overwrite magneto-optical disk

It is demonstrated that the direct overwrite (DOW) magnetooptical (MO) disk to which a GdFeCo readout layer has been added shows a 21% window margin for data recorded at 0.54 μm/b density, twice the first-generation recording density. The addition of a GdFeCo readout layer raises the carrier level and lowers the modulation noise level several decibels. This improved DOW-MO disk also shows a carrier-to-noise ratio of 53 dB at 0.75-μm mark length, which is several decibels higher than is typical for the first-generation MO disks. Data at a density of 0.54 μm/b have been recorded on the improved DOW-MO disk, using a write precompensation scheme in the timing of laser power. A 21% window margin in discrimination of the data recorded at this density has been achieved. A different write precompensation scheme which enhances falling edges of laser pulses also demonstrates a remarkable improvement in discrimination of these high-density recordings on the improved DOW-MO disk