High-Track-Density Flattened Magnetooptical Disks with Low Crosstalk

Abstract

The carrier-to-noise ratio (CNR), crosstalk and noise levels have been investigated for flattened and semiflattened magnetooptical disks with narrow track pitches of 1.2 and 1.0 µm. The track pitch of the flattened and semiflattened disks can be reduced to less than the laser spot size under the condition that the laser spots irradiated on the adjacent recording regions overlap each other only on the spiral guiding band. The CNR of 48.3 dB and low crosstalk of less than -36 dB were achieved for the track pitch of 1.2 µm when the domains of 0.76 µm length were recorded. Crosstalk of less than -30 dB was obtained for the track pitch of 1.0 µm with the conventional optical head having an objective lens of 0.53 NA and a 780-nm laser.