4.7 GB Phase Change Optical Disc with In-Groove Recording

We developed a rewritable optical disc with 4.7 GB/side capacity as an extension of the digital versatile disc recordable (DVD-R) system. The disc is readily playable on a read-only DVD player or a DVD-ROM drive with a small firmware modification. As far as the fundamental characteristics of the disc which adopts an in-groove recording are concerned, the reflectivity is 18% or more, modulated amplitude is 60% or greater, and jitter is 8% or less. As we had sufficient differential phase detection (DPD) tracking error signals from the recorded disc, we think the DPD tracking method is practical. These results cleared the single-layer DVD-ROM specifications except for the reflectivity. The measured reflectivity satisfies the specifications of the dual-layer DVD-ROM disc. Furthermore we confirmed that the recorded disc was playable on a blue laser playback system.