Benno Tieke

Recent Developments in Thermal Modelling of High-Speed Dye Recording

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.

Thermally Balanced Writing for High-Speed Compact Disc Recordable (CD-R) Recording

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.

Recording CD-R up to 56x

The most important performance parameter for CD-R recording is the recording speed. We have achieved recording speeds of up to 56X on CD-R with a data-to-data jitter of 25 ns that is well within Orange Book specification. This jitter is achieved at zero asymmetry and with a write power margin of 20% of the optimum recording power. In this paper, we present results on a number of CD-R media. Furthermore, we discuss the influence of write strategy parameters, such as laser power level, laser pulse length, pulse shape, etc., on the recording performance of high speed CD-R.

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

Today’s major trends in optical recording are the increase in storage capacity per disc and the increase in data-rate, both for reading and for writing. To enlarge the capacity, there are two straightforward means to reduce the optical spot size: increase of the numerical aperture of the objective lens (NA) and reduction in laser wavelength λ.