Low Thermal Budget Optical Recording: A Method for Higher Recording Densities

摘要

The recording of amorphous marks in crystalline Chalcogenide tracks of rewritable optical storage media depends critically upon management of the total thermal budget. This management depends not only directly on the physical make-up of the optical device, but also importantly depends on the recording strategy. We show through analytical and numerical calculations that the heating during a laser pulse or cooling after the end of the pulse can be described in terms of two mechanisms having very different time constants. The short and long term mechanisms have time constants of about 1 ns and more than 6 ns, and are governed by thermal capacitance and thermal conductance, respectively. A low thermal budget (LTB) recording strategy makes use of the fast component to achieve greater control over the shape of the amorphous mark. Such control over the shape may find use in a multi-level recording strategy. Moreover, even in binary recording, LTB offers greater control over the amorphicity of the marks compared to standard write strategies by preventing back crystallization during middle pulses. This should lead to lower jitter values, which would allow the incremental mark size to be reduced and thus yield greater storage capacity.