Irregularities in the edge of the bit marks is one of the most critical sources of the noise that lead to timing jitter in optical phase change recording. The maximum linear bit density achievable at a given wavelength and lens numerical aperture is often limited by jitter. Jitter is largely determined by the combined optical, thermal, and crystallization properties of the medium and by the optical quality and recording strategy of the laser beam. Media with a patterned phase-change layer are proposed for controlling the mark edge jitter by making distinct mark edges. The preliminary simulation results from writing on the transverse and longitudinal patterns look promising in producing rectangular bit marks with distinct boundaries. The bit marks written on patterned media also have a smaller size compared to those written on continuous media. An interesting and unexpected result is the disappearance of the crescent-shaped trailing edge in all the bit marks on the patterned media, the shape and existence of which can have a great effect on the trailing edge jitter. Writing on grooved media has also been simulated for further comparison. In the present investigation a simulation code is developed using commercial finite element analysis software for the heat transfer simulation, with a custom-integrated crystallization model.
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