Dual-Layer Optical Disk with Te–O–Pd Phase-Change Film

A recordable dual-layer optical disk that uses a Te–O–Pd phase-change film was studied for high-density recording. In order to reduce thermal influence to adjacent tracks, we selected the optimum composition of Te42O46Pd12 that gives low thermal conductivity. To get equivalent signal amplitude and absorbance of layers, the thicknesses of the laser incident side recording layer (Layer 1) and the other layer (Layer 2) are designed to be 20 nm and 55 nm, respectively. We confirmed that there was less than 10% bottom jitter for both layers under the following recording densities: recording bit length of 0.41 µm and track pitch of 0.74 µm. The laser powers required for recording on Layer 1 and Layer 2 were typically 10 mW and 12 mW, respectively. The jitter was less than 13% for both layers with large power tolerance of 30%p-p.