A thermally balanced write strategy has been developed for high-speed recording of CD-recordable (CD-R). It is adopted in the recent multi-speed CD-R standard as the media testing condition. The write strategy accounts for the effects of thermal interference and heat accumulation during the recording process. Detailed thermal calculations of the resulting pit shapes and sizes support the approach. CD-R recording speeds of up to 40X are demonstrated using this Thermally Balanced Write Strategy.

We discuss a generic method to validate a numerical model that can be applied to high-speed dye recording. The method is based on the determination of transition powers that correspond to the onset of pit formation. The mechanism of pit formation is discussed in terms of the decomposition of the recording dye and the softening of the polycarbonate substrate. The decomposition temperature of compact disc (CD) and digital versatile disc (DVD) dyes was measured with two different methods, involving heating rates that approach those encountered during recording. The softening temperature of polycarbonate was also measured. The laser powers required for the onset of dye decomposition and softening of the polycarbonate-dye interface were determined from continuous-writing (DC-write) reflection measurements for 1X-40X CD-R recording and 1X-10X DVD+R recording. In addition, transition powers were obtained from atomic force microscopy (AFM) analyses of written tracks. The DC-reflection and AFM-topography measurements appear to collapse onto one generic master curve for the entire range of tested recording velocities for each type of CD and DVD. From the measured temperatures for the onset of dye decomposition and polycarbonate softening, transition powers were also calculated with a numerical model of the multilayer recording stack. Numerical results are compared with experimental values for a CD and DVD type of disc.

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 (λ=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 (λ=400 nm) in our recording set up, a capacity of 21.5 GB was achieved at a data-rate of 28 Mbps.