Masaichi Nagai

Single‐beam overwriting with melt‐erasing process in an InSbTe phase‐change optical disk

Single‐beam overwriting with melt‐erasing process was made in a 5.25‐in.‐diam phase‐change optical disk using an In22Sb37Te41 recording film. In the overwriting between 2 and 3 MHz signals at the linear velocity of 3–11 m/s, a carrier to noise ratio (C/N) more than 46 dB and an erasability less than −35 dB could be obtained. This high erasability was found to be due to the melt‐erasing process. This disk presents highly erasable overwriting and long data retention time supported by an activation energy of 2.3 eV and a temperature of 230 °C for crystallization of the amorphized part.

Overwritable phase-change optical disk using an In3SbTe2 ternary compound

By employing transmission electron microscopy and thermal ana1yis, we examined overwrite repeatability of optical disks using In-Sb-Te alloys, which have high C/N ratio and excellent overwrite modulation characteristics. The overwrite repeatability of more than 105 was achieved by using an In3SbTe2 single-phase ternary compound and heat-flow balanced disk structure.

Disk structure for high performance overwritable phase-change optical disks

Disk structure for high performance overwrite using an InSbTe recording film was examined and the results were analyzed by a computer calculation. It was confirmed that dielectric films and reflective films have great influences on the sensitivities of melting and amorphization of the recording film. It was suggested that the thermal contact between the dielectric film and the reflective film is important for stable overwrite repetition.

40 dB OVERWRITE -MODULATION PHASE- CHANGE OPTICAL DISK USING In -Sb -Te ALLOY

A single-beam overwrite was achieved by an In-Sb-Te phase-change optical disk. The carrier to noise (C/N) ratio of more than 50 dB and the overwrite modulation of -40 dB were obtained for overwriting frequencies of 2 MHz and 3 MHz using a low power laser diode of 30 The high C/N ratio and the excellent overwrite modulation were due to the large reflectivity difference between the written and erased phases and the use of suitable write/erase power.