Simplified Transfer Function of Write Compensation for Phase-Change Optical Disks

A simplified transfer function for write compensation is given by the inverse function of the cooling transfer function of a phase-change optical disk. The areas at a phase-change recording layer irradiated with an optical beam melt and change to marks. The marks are formed when the area is rapidly cooled; however, the marks disappear in a slowly cooled situation. Thus, the cooling process was considered essential for the mark formation on a phase-change optical disk. Therefore, the transfer function of the mark formation combined a heating component before mark formation with that after mark formation using a lag element. It was also found that the transfer function for write compensation could be achieved using a two-stage pulse train method. Experimental results showed that long marks were recorded by the pulse train method with the same frequency characteristic as our theoretical analysis. (c) 2013 The Japan Society of Applied Physics