Extension of Linear-Velocity Margin in Phase-Change Optical Recording with Variable-Pulse Compensation

概要

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Using a variable-pulse compensation method, it was demonstrated that a phase-change optical disk consisting of a stoichiometric Ge_2Sb_2Te_5 active layer and a fixed rapid cooling multilayer structure, which was designed for use at high linear velocity of over 5 m/s, exhibited a satisfactory read/write performance for a wide range of linear velocity, 1.4 m/s-10 m/s. The variable-pulse compensation method includes a variable-pulse division strategy in accordance with the linear velocity in pulse-width modulation recording. For recording an amorphous mark which is nT length (n: integer, T: the length of one clock cycle), the pulse duration of each divided writing pulse in the nT period was reduced and laser power was optimized at lower linear velocity to suppress the undesirable heat accumulation in the laser-irradiated area that leads to shrinking the amorphous mark. This assures exact control of molten area formation and its cooling process to obtain clear edges of amorphous marks, and overcomes the recrystallization around the mark in overwriting that is predominant in the low-linear-velocity regime.
社団法人応用物理学会の論文
1997-01-30