PHASE-CHANGE OPTICAL DISKS HAVING RECORDING MARKS WITH LARGE OPTICAL-PHASE DIFFERENCE SUITABLE FOR MARK EDGE RECORDING

We have developed a novel absorptivity control method for phase change optical disks with the aim of reducing overwriting jitter in mark edg e recording without degradation of overwriting cyclability. To control absorptivity more easily, we have designed a disk with a small differ ence in reflectivity between the amorphous and the crystalline states, and with a large optical phase difference between the reflected light from those two states, which produces a high carrier-to-noise ratio. We have obtained significantly reduced overwriting jitter, down to 2.5 ns for the leading edge, as well as a sufficient overwriting cyclabil ity of up to 10(5) times.