High data-rate phase-change media for the digital video recording system

The digital video recording (DVR) system combines a high numerical aperture (NA = 0.85) with a thin cover layer to achieve higher storage capacities in optical recording. In addition to capacity. the data-rate is a key parameter for DVR and a major challenge in research on phase-change materials. Using Ge2Sb2Te5 as the phase-change material, we demonstrate recording using a red laser diode (lambda = 650 nm) at a user data-rate of 33 Mbps and a capacity of 9.2 GB for a single layer disc of 12 cm diameter, i.e. completely satisfying all the DVR system requirements. In addition, we achieved data-rates of up to 50 Mbps by applying a different stack design. Furthermore, we extend DVR to the blue-violet wavelength region. Using a GaN laser diode (lambda = 400 nm) in our recording set up, a capacity of 21.5 GB was achieved at a data-rate of 28 Mbps.